The impact of the COVID-19 pandemic on healthy volunteer motivations: a mixed-methods study of participants in plague vaccine trials in the UK and Uganda

The impact of the COVID-19 pandemic on healthy volunteer motivations: a mixed-methods study of participants in plague vaccine trials in the UK and Uganda | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The impact of the COVID-19 pandemic on healthy volunteer motivations: a mixed-methods study of participants in plague vaccine trials in the UK and Uganda Arabella Stuart, Richard Muhumuza, Sylvia Kusemererwa, Maria Teddy Ndagire, and 13 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6657828/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 17 You are reading this latest preprint version Abstract Background The COVID-19 pandemic led to unprecedented interest and participation in vaccine trials globally, and a concurrent increase in vaccine hesitancy. Whether this impacted recruitment of healthy volunteers to subsequent non-COVID vaccine trials is not well studied. We explored the impact of the COVID-19 pandemic on motivations for participating in two clinical trials of the same novel anti-plague vaccine, conducted in the United Kingdom (UK) and Uganda in 2021 and 2022. Methods Participants enrolled in PlaVac (UK) and PlaVac Uganda, Phase I trials of ChAdOx1 Plague vaccine, were invited to complete an optional questionnaire and semi-structured interview examining motivations for participating, including questions on the impact of the COVID-19 pandemic on their decision. Questionnaires were self-administered and interviewer-administered for UK and Uganda studies, respectively. Interviews were conducted in local languages, transcribed in English, and analysed using thematic analysis. Results were compared between studies. Results Thirty-one of the 45 (25.8% female) UK trial participants and all 36 (27.8% female) of the Uganda trial participants completed questionnaires. Nine UK questionnaire respondents, and 19 Uganda questionnaire respondents completed interviews. Responses to questions on the impact of the COVID-19 pandemic on volunteering decisions were divergent between countries, with little effect for UK participants but a strong positive effect for Ugandan participants. Themes relating to this effect in Uganda were preparedness (wanting to contribute to vaccine development to prevent suffering and death from future epidemics), increased awareness (understanding the vaccine development process and seeing rapidly deployed COVID-19 vaccine trials gave them confidence), and personal protection (believing themselves to be protected by the novel plague vaccine). Participants in both studies expressed trust and confidence in the study plague vaccine which shares the ChAdOx1 platform with the ChAdOx1 nCoV-19 (Vaxzevria, AstraZeneca) vaccine. Conclusions For Ugandan participants, COVID-19 and mass vaccination increased knowledge about vaccines and trials and encouraged them to participate in research, but had little impact on UK volunteers. There was no evidence of a negative effect of perceptions of the related ChAdOx1 nCoV-19 vaccine on trial participants' confidence in the novel plague vaccine's safety. Trial registrations Current controlled trial: ISRCTN41077863, prospective registration date: 19/03/2021, and current controlled trial: ISRCTN79243381, prospective registration date 05/08/2022. Plague vaccine motivations COVID-19 healthy volunteers Figures Figure 1 Figure 2 Background The COVID-19 pandemic of 2020-2023 was a global health crisis unprecedented in modern times, with seven million direct deaths, an excess mortality rate of two to four times this, and associated profound economic and social disruption. 1-6 This prompted a global race to develop vaccines, with over 288 trials registered between 2020-2021. 7 These trials took place in the context of what the World Health Organisation (WHO) described as an “infodemic” of information and misinformation, in addition to countries’ own awareness and health campaigns, and whilst at the time there was a surge in interest vaccine trial volunteering, there was also a rise in vaccine hesitancy, which has persisted beyond the pandemic. 8-13 Early-phase vaccine trials rely on recruiting “healthy volunteers”; people who usually do not stand to benefit from the study intervention, and run the risk of incurring harm from study procedures or adverse reactions 14, 15 . Healthy volunteers' motivations to participate in vaccine trials are less well studied than those for non-vaccine drug trials, but in diverse income settings have been found to encompass altruistic motivations, desires to contribute to science and financial and non-financial benefits of participation. 16-18 Evidence from studies of COVID-19 trial volunteers in both high- and low-income countries suggests differences to pre-pandemic volunteers, with motivations directly linked to contributing to a mitigation of the social and individual suffering caused by the pandemic, and a sense of urgency for the need to take action in the face of a pressing health crisis. 10, 19-21 Participant motivation is an important aspect of trial participation as it affects recruitment, informed consent, and retention. 18, 22-26 For example, high financial compensation can over-incentivise participation leading volunteers to enrol in trials without due consideration of potential risks, potentially invalidating the concept of informed consent. 27, 28 . Non-financial compensation such as free healthcare during study participation has been noted to be particularly incentivising in low-resource settings. 29-32 What is not yet known is whether the COVID-19 pandemic influenced the decision to volunteer for participants in non-COVID-19 vaccine trials, many of which were delayed or suspended during the acute phase of the pandemic in 2020-2021. 33 Whilst COVID-19 is the most recent pandemic of modern times, plague, a lethal disease caused by the bacterium Yersinia pestis , tends to be considered a historical disease. 34 This is unfortunately a misconception, as plague is globally distributed in endemic foci, and is classified as a “re-emerging” disease with up to 700 cases annually. 35, 36 Despite this, there is no licenced vaccine approved by the WHO. 34, 37 Over 90% of annual cases occur in rural and medically underserved communities in sub-Saharan Africa, including Uganda which contains both endemic foci in Northern regions and is vulnerable to cross-border transmission from the Democratic Republic of Congo. 38, 39 Efforts to develop a modern vaccine have thus far failed. 40 A novel plague vaccine, ChAdOx1 Plague, has been developed by the University of Oxford and underwent Phase I testing in two trials, the first (PlaVac) in Oxford, United Kingdom (UK) starting in late 2021, and the second (PlaVac Uganda) in Masaka, Uganda in early 2022. These trials were positioned in a unique context; both studies began enrolling participants after the commencement of mass COVID-19 vaccination campaigns and the easing of non-pharmaceutical interventions (e.g. social distancing) in their respective countries, and the trial vaccine is closely related to the ChAdOx1 nCoV-19 vaccine (Vaxzevria, AstraZeneca) which had been extensively used in COVID-19 vaccination campaigns in both countries. 41-45 Additionally, recruitment for both studies took place after there had been pauses in multiple countries’ use of the vaccine due to the occurrence of fatal blood clotting events; what later became known as vaccine-induced immune thrombocytopenia and thrombosis (VITT), which garnered extensive media coverage, including in Uganda – and at the time it was unknown what impact this would have on recruitment. 46-51 As part of the PlaVac trials, mixed-methods study procedures comprising a questionnaire and semi-structured interview examining the volunteering motivations and experiences of trial participants were conducted. Data showing the impact of the COVID-19 pandemic on participants motivations and trial experience will be presented here. Methods Study setting and population Mixed-methods study procedures were included in two phase I studies of an investigational plague vaccine, ChAdOx1 Plague. PlaVac (ISRCTN:41077863) was a Phase Ia trial conducted at the Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK, and PlaVac Uganda (ISRCTN:79243381) a Phase Ib trial conducted by Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit field station in Masaka, Southwestern Uganda, where plague is not present. The primary endpoint of both Phase I trials was the safety and tolerability of ChAdOx1 Plague in healthy adults. To be eligible for participation in the PlaVac trials, volunteers had to provide written informed consent, be considered medically healthy, not pregnant or lactating, and adherent to contraception for the duration of the trial. Age inclusion criteria were 18-55 years for the UK study and 18-49 years for the Uganda study. The lower inclusion age-range for the Uganda study was based on the progress of the Uganda COVID-19 vaccination rollout at the time of study design, with the decision to exclude the most prioritised over 50 age group, due to the risk of discencentivising take up of COVID-19 vaccination through study participation as there were temporal exclusions around receiving other vaccines once enrolled in the study. Study design, sampling, and sample size For mixed-methods procedures a convergent parallel design was used. Quantitative and qualitative data were collected concurrently, analysed independently and combined in interpretation. 52 Participation in mixed-methods procedures was optional in both studies. For the PlaVac UK study, all participants were invited to complete the questionnaire, with the optional additional completion of an in-depth interview using a semi-structured guide. For PlaVac Uganda, all participants were invited to complete the questionnaire, and optionally the interview. Participants who wished to complete an interviews were purposively sampled, aiming to include equal numbers of males and females. All participants were reimbursed for study visits, to cover transport and time expenses, as per local guidelines. Participants had received information on plague via study information-giving sessions (Uganda only) and via the participant information sheet and informed consent process.Data collection and analysis For the quantitative component, a 47-item questionnaire was developed based on the literature review, and experience of conducting a survey of COVID-19 trial volunteers (Supplementary Table 1 and Supplementary Table 2). 10 Questionnaire domains included demographics, previous experience of clinical trials, attitudes to blood and organ donation, motivations for volunteering for the study, views on risks of the study and experiences of study participation. The questionnaire was reviewed by the PlaVac Uganda study team, with modification of questions for cultural appropriateness. Both questionnaire versions were piloted with local teams before finalisation. Questionnaire data were collected in JISC Online Surveys V2. UK participants completed questionnaires in privacy via a single-use URL sent by the study team. UK responses were pseudo-anonymised through an embedded token in the email link, meaning data was extractable from the survey platform in a fully anonymised format, but participant responses could be tracked. Uganda questionnaires were administered by a researcher who was not previously known to the participant or part of the clinical team, with direct data entry using a laptop. There was no linkage of identifiers between mixed-methods procedures and the main study data. Data were analysed descriptively using StataSE V18.0 (StataCorp, Texas, USA) and Microsoft Excel (v2404). For the qualitative data, an interview guide was developed based on questionnaire domains, using pre-scripted open-ended questions and prompts, and was reviewed and modified by the Uganda study team for use in PlaVac Uganda (Supplementary Table 3, Supplementary Table 4). The guide was piloted among staff at both study sites who were not familiar with the study, to ensure flow and comprehensibility of the prompts. UK in-depth interviews were conducted via video call (Microsoft Teams) by a researcher not previously known to the participant. Uganda the in-depth interviews were conducted in person after questionnaire administration, by the same researcher who conducted the questionnaire. Interviews were conducted in Luganda transcribed verbatim in English and organised using Nvivo 12 Pro (QSR International). Transcripts were fully coded, with codes generated using inductive and deductive approaches. For the Uganda data, transcripts were coded by two researchers, with iterative development of the codebook. Thematic analysis was conducted to generate themes and code the data. 53 Results Participants Enrolment to PlaVac UK took place between August and October 2021, with 45 participants, and enrolment to PlaVac Uganda in March 2022, with 36 participants. Thirty-one of the 45 PlaVac UK participants completed the optional questionnaire, and nine of those the interview. All 36 PlaVac Uganda participants completed the optional questionnaire, and 19 of those completed an interview. Demographics of questionnaire participants There was a higher proportion of questionnaire participants in younger age categories in Uganda than in the UK, with 72.2% vs 48.4% falling in 18-34 years. Both samples were >70.0% male, which was reflective of the overall study composition (Supplementary Table 5). Uganda participants were predominantly of Christian religions (86.1%), whereas most UK participants had no religion (64.5%). Over half of the Uganda cohort had received only primary education (52.8%), whereas 64.5% of the UK cohort had a university degree. Most participants in both studies were employed (for Uganda participants, employed was defined as having done work in the past 7 days), 94.4% vs 83.9% in Uganda and UK, respectively. UK participants were more likely to be experienced trial volunteers, with 54.8% (n=17) having previously been in a clinical trial, versus 5.6% (n=2) of the Uganda participants. All UK participants had completed at least eight of the 12 months of study follow-up, and Uganda participants had completed at least five of the seven months. (Table 1) Demographics of interview participants Due to purposive sampling, the Uganda participants had more even gender balance, whereas UK remained with a male preponderance (66.7%). Older participants were over-represented in UK interviewees, and Uganda interviewees’ ages were more similar to the questionnaire cohort, with the largest age group being 25-34 years. (Table 2) Table 1. Demographics of PlaVac UK and Uganda questionnaire participants. UK (N=31) Uganda (N=36) n (%) n (%) Age category 18-24 years 8 (25.8%) 13 (36.1%) 25-34 years 7 (22.6%) 13 (36.1%) 35-44 years 6 (19.4%) 9 (25.0%) 45-49/55* years 10 (32.3%) 1 (2.8%) Gender Male 22 (71.0%) 26 (72.2%) Female 8 (25.8%) 10 (27.8%) Other 1 (3.2%) (-) Religion No religion 20 (64.5%) 0 (0.0%) Christian~ 10 (32.3%) 31 (86.1%) Muslim 0 (0.0%) 5 (13.9%) Other religion # 1 (3.2%) 0 (0.0%) Ethnicity White - British 27 (87.1%) (-) White - Other 1 (3.2%) (-) Mixed - White and Black Caribbean 1 (3.2%) (-) Mixed - Other 1 (3.2%) (-) Prefer not to say 1 (3.2%) (-) Black African 0 (0.0%) 36 (100.0%) Education^ Primary (-) 19 (52.8%) Secondary school/ up to 16 years (UK) 1 (3.2%) 13 (36.1%) Higher secondary/further education/more than secondary $ 10 (32.3%) 4 (11.1%) University bachelor's degree 11 (35.5%) Postgraduate degree 9 (29.0%) Employment status Employed full time 20 (64.5%) 34 (94.4%) Employed part time 3 (9.7%) Unemployed and currently looking for work 1 (3.2%) 2 (5.5%) Student 3 (9.7%) Homemaker 1 (3.2%) Self-employed 3 (9.7%) Type of employment Education, law, social, government services 6 (19.4%) 2 (5.6%) Health 5 (16.1%) 1 (2.8%) Business/Finance 3 (9.7%) 6 (16.7%) Carer for other household member 1 (3.2%) 1 (2.8%) Sales and services 3 (9.7%) 6 (16.7%) Management 3 (9.7%) (-) Natural/applied science 3 (9.7%) (-) Student 3 (9.7%) (-) Other 4 (12.9%) (-) Trades and transport (-) 12 (33.3%) Craft and related trades (-) 3 (8.3%) Agriculture (-) 4 (11.1%) Marital status Single (never married) 13 (41.9%) 17 (47.2%) Married 7 (22.6%) 14 (38.9%) Separated 0 (0.0%) 3 (8.3%) Cohabiting 7 (22.6%) (-) Divorced 3 (9.7%) 1 (2.8%) Prefer not to say 1 (3.2%) 0 (0.0%) Widowed 0 (0.0%) 1 (2.8%) Number of children None 18 (58.1%) 10 (27.8%) One 5 (16.1%) 7 (19.4%) Two 6 (19.4%) 4 (11.1%) Three 2 (6.5%) 2 (5.6%) Four 0 (0.0%) 6 (16.7%) Five 0 (0.0%) 2 (5.6%) Six 0 (0.0%) 2 (5.6%) Seven 0 (0.0%) 1 (2.8%) Eight 0 (0.0%) 1 (2.8%) Prefer not to say 0 (0.0%) 1 (2.8%) Household income Less than £15,000 2 (6.5%) (-) £15,000 - £24,999 3 (9.7%) (-) £25,000 - £54,999 6 (19.4%) (-) £55,000 - £99,999 11 (35.5%) (-) £100,000 - £149,999 5 (16.1%) (-) £150,000 or more 2 (6.5%) (-) Prefer not to say 2 (6.5%) (-) Have you ever been in another study before this one? Yes 17 (54.8%) 2 (5.6%) No 14 (45.2%) 34 (94.4%) * Upper inclusion age range UK/Uganda ~includes Catholic, Protestant and all other Christian denominations #“Agnostic” free-text ^Education includes completion of any grade within that category $Includes vocational and professional training Table 2. Demographics of PlaVac UK and Uganda interview participants UK (n=9) Uganda (n=19) Gender n (%) n (%) Male 6 (66.7%) 10 (52.6%) Female 2 (22.2%) 9 (47.4%) Non-binary 1 (11.1%) (-) Age category 18-24 years 2 (22.2%) 5 (26.3%) 25-34 years 0 (0.0%) 9 (47.3%) 35-44 years 2 (22.2%) 5 (26.3%) 45-55/49* years 5 (55.6%) 0 (0.0%) Religion Christian - 13 (68.4%) Muslim - 5 (26.3%) Not given - 1 (5.3%) Education^ - Primary - 11 (57.8%) Secondary - 4 (21.1%) More than secondary^^ - 4 (21.1%) Category not collected for either study *Upper limit 55years for UK and 49 for Uganda at time of enrolment ^Education includes completion of any grade within that category ^^Includes vocational and professional training Impact of the COVID-19 pandemic on decision to volunteer for the trial Participants in both studies were asked about the impact of the COVID-19 pandemic on their decision to volunteer for the PlaVac trials (Figure 1). When asked about the impact of the pandemic on their awareness of clinical trials, and whether this influenced their volunteering decision, fewer than a third of UK respondents (30.6%, n=11) overall agreed, versus 97.2% (n=35) of the Ugandan participants. UK participants also generally disagreed with the statement “Before the COVID-19 pandemic I would not have volunteered for this kind of study” at 74.2% (n=23), whereas Ugandan participants gave mixed responses with 47.2% (n=17) overall agreeing, 41.7% (n=15) overall disagreeing, and 11.1% (n=4) being neutral. In keeping with questionnaire responses, UK interviewees did not spontaneously mention the pandemic as having been a motivator. When probed by the interviewer, it was described as either having no impact at all, or as a contributing, but not definitive motivator: “I don’t know if I would have taken part before [the COVID-19 pandemic], or not taken part, I think, but I think this [the pandemic] definitely pushed me towards a yes, I should take part in a vaccine study”. (UK05, 45-55years) A single participant described how it has increased his interest in the process of vaccine development: “through the pandemic, it was like a chance where I wanted to try and help out, so I signed up to the St. John's [St.John’s Ambulance Service – voluntary healthcare organisation assisting with vaccinations]to become a vaccinator, to try and expose myself to more of like the clinical side. And I was interested in how vaccines come from being discovered, to going through trials, to being manufactured, and then delivered. I thought the best way to learn was if I could put myself in the different steps and see it from the inside, so it sort of played a part, yes.” (UK08, 18-24years, M) Uganda interviewees prominently described COVID-19 as having been a motivator, which could be grouped under themes of “preparedness”, “increased awareness” and “personal experience”. Preparedness – “COVID-19 killed many people” Participants drew a parallel between the abrupt onset and high mortality of the COVID-19 pandemic and the potential for another disease without a ready vaccine, such as plague, to do the same. “COVID-19 killed so many people and it also motivated me to participate in the plague vaccine trial to get medication that can help people if there is an outbreak … If there is an outbreak of plague without medication, it can also kill so many people as COVID-19 did. ” (UG34, 25years, M) Some participants drew a specific link between the risk of being unprepared for an epidemic, and the continued presence of plague in Uganda: “Interviewer: do think Plague is a big problem in Uganda or it is not? Interviewee: It is not a big problem because of the low number affected by it but if it gets worse it can be trouble in case we have no vaccine. That is why a vaccine is needed so that we do not get other things like COVID which got us not prepared. Because all is possible” (UG5, 26years, F) Another element of preparedness was the need to have a vaccine to avoid the use of non-pharmaceutical disease control interventions that caused so much economic and social hardship: “It motivated me greatly because the situation was not easy and the way the disease [COVID-19] broke out in a way we did not understand…first we were locked down and not free to move from our places to go to other places. The finances were greatly affected and the disease also claimed a lot of lives every day. Item prices increased rapidly. When someone coughed it would worry you and cause you to distance from them. In case you saw a stranger in the village you would worry about him, you would wonder what they are looking for, we did not want anyone coming to our home” (UG29, 35years, F) Increased awareness – “It opened people’s eyes” Matching the questionnaire responses, many Ugandan interviewees reported the COVID-19 pandemic had increased their knowledge of the process of vaccine development and clinical trials, and this had positively influenced their decision to volunteer. Interviewees reported being sensitised through COVID-19 vaccination information campaigns on television and radio, which had increased their confidence, enabling them to act on their desire to contribute to the protection of their communities: “COVID scared me and I refused to get vaccinated. It was during COVID that I heard on the radio about the process of first trying the vaccine on animals and later on people. I heard that on the radio before coming here for the study. When the study came into my community it helped me to understand more and I decided to participate because it helped me to learn to contribute. After all, you or your family could get that disease or anyone in the community. Like the way COVID broke out in the community. So, I decided to participate so that researchers can do their best as we contribute through participation” (UG25, 36years, F) This increased knowledge and awareness also affected participants’ perception of the safety of vaccine trials, both through being told about the development process, and through witnessing others be safely vaccinated: “Yes, it opened people’s eyes to understand that trying vaccines on you does not kill you. As they used to think about it. Because even the COVID-19 vaccine had been tried on people in a short time” (UG11, 26years,F) “Interviewer: Do you think COVID increased awareness about vaccine trials? Interviewee: Yes sir, It greatly contributed to vaccine trial awareness because I expect that all that accepted to participate in this study greatly relied on that. And the time they sent us the COVID vaccine, you would know that there are also people who stood in for us or who surrendered themselves to get the vaccine. It was equally tried on people. They just did not get it out of the blue and injected it in people. And we did not get news that when that vaccine was tried on a group of people in a particular area they were harmed. We did not get that kind of news” (UG29, 35years, F) Personal protection – “I will be safe” Participants are explicitly counselled during the consent process that the vaccine is new, and it is unknown whether it would offer any protection against plague disease. However, in both interviews and free-text responses to the questionnaire, some participants (both young and old) were motivated to participate because they believed receiving the novel plague vaccine would protect them from a future outbreak. This need for personal protection was also explicitly linked to their experiences of the COVID-19 pandemic: “My major reason was COVID-19 because I heard it affected many people and many died so I decided to also get vaccinated because in case of an outbreak. We were told the plague had broken out before. I went and asked my elder sibling who also told me the plague was here in the early days. I thought if I take this opportunity to get vaccinated even when it breaks out, I will be safe”(UG25,36y, F) “To see that I help others and also help myself by getting a vaccine to prevent myself from getting plague … The reason for the way I saw people dying and the condition in which they were living. Indeed, and when a chance came and there was a trial, I said let me give in myself to try this in that even when this breaks out. I can survive it” (UG36, 29years, M) Whilst most participants describing “personal protection” felt it was likely the vaccine would be effective, a few were aware that it could fail, but still felt it was worth having: ‘’I was greatly motivated by the fact that back in the day we had been hit by COVID. The situation we went through was not good. Now when they taught us about participating in studies, it’s the truth that someone has got to fight for themselves and also fight for his nation...If the vaccine gets to be successful. It will have saved me and also save others.’’ (UG29, 35y, F) “The other thing is that I expected that if I come and God helps me and this vaccine succeeds it means that even when Plague breaks out. I will not be worried because I will be aware that I was vaccinated. If this vaccine works my body will be able to have the antibodies that fight plague” (UG22, 23y, M) Two plagues, two vaccines – ChAdOx1-nCoV-19 and ChAdOx1 Plague At the time of enrolment, all PlaVac UK participants had received at least one dose of COVID-19 vaccine, versus 30.6% of PlaVac Uganda participants. Over half of the UK participants had received ChAdOx1-nCoV-19, as had 62.5% of Uganda participants who had received a COVID-19 vaccination (Supplementary Table 5). The vaccination status of the questionnaire and interviewparticipants was not specifically recorded, but some participants discussed their COVID-19 vaccination status at interview. Participants were asked about their perception of the safety of the plague study vaccine in relation to its similarity to the ChAdOx1-nCoV-19 (Vaxzevria,AstraZeneca) COVID-19 vaccine (Figure 2). In both studies,this similarity was reassuring, with 67.7% (n=21) of UK participants and 80.6% (n=29) of Ugandan participants overall agreeing that this made them feel the study vaccine was likely to be safe. When asked whether they worried about the risk of vaccine-induced thrombosis with thrombocytopenia (VITT, described to participants as blood clots related to the vaccine) in both studies relatively small proportions agreed they had concerns, at 16.1% (n=5) of UK participants and 22.2% (n=8) of Ugandan participants. Interview responses from both studies elucidated reasonings behind responses on the link between the two ChAdOx1 vaccines and the perceived risk of the trial, with themes of “safer because ChAdOx1” and “negative press and rumours” emerging. Safer because ChAdOx1 – “it’s the same thing” As with the questionnaire responses, many interviewees in UK and Uganda studies drew a link between the use of ChAdOx1-nCoV-19 as a pandemic vaccine, and the potential riskiness of the plague trial vaccine; with most participants feeling that this made it safer. In keeping with the difference in proportions previously vaccinated with ChAdOx1 nCoV-19 between the two studies, UK interviewees were more likely to link the experience of being personally ChAdOx1 nCoV-19 vaccinated with the perception of safety, whereas Uganda participants were more likely to report witnessing its use in their communities as the reassuring factor; although some interviewees had been also vaccinated with ChAdOx1 and also found this personally reassuring . “I had previously had a ChAdOx1 vaccine against COVID, so obviously, so there's one thing there which is sort of like, you know, I have been injected with this vector before. So that's a few of the things that you might imagine that might go wrong, that you could, that even just for me, I have had experience of having that vaccination so, you know, I'm thinking I look, I was looking at it, as this is a sort of, this is basically a fairly similar vaccination with a slightly different bit of... A slightly different bit pasted in. So I was assuming the risk was fairly low” (UK06, 45-55years, M) “It made me stronger in a way that if the vaccine is in any way related to that of COVID. Those vaccinated against COVID are many and I did not hear that someone died because of getting vaccinated” (UG29, 35y, F)Negative press and rumours – “these things did not happen” Only a single participant, in the UK study, mentioned hearing about negative events related to the ChAdOx1-nCoV-19 vaccine in the media, but this did not affect their confidence that the vaccine platform would be safe: “Like I don't believe I'll be an anomaly [have a rare side effect]. I don't think I'll have adverse reactions to it. So I didn't, I don't think I ever really thought that it was a bad thing that it was based off of that, due to that history [of episodes of VITT reported in media]. I thought it was more of a good thing because it's based off of that [ChAdOx1 vaccine platform], and that that's something that's been working, you know? ... So I don't think it made me think any worse of it just because of what media has said because you can't trust everything in the media” (UK03, 18-24years,F) Participants in the Uganda study did report rumours they had heard about COVID-19 vaccination, and many had been personally afraid of being vaccinated: “We were scared of death. We were suspicious of the vaccine.” (UG35,40years, M) The most common rumours were that the vaccine would kill you, or would cause sterility and was a method of population control: “I thought that the vaccine would kill me. Okay at first we were so fearful. You could think that what if they inject me and the vaccine is aimed at reducing on the number of people in the country” (UG01,26years,M) Key in alleviating fears about COVID-19 vaccination was witnessing others not experience adverse effects from vaccination, and this gave confidence to participate in the PlaVac trial: “…for COVID-19 I was even scared of the injection [vaccine] as people said the moment you get the injection you are going to die. My children went first for that vaccine but when they came back home I saw that nothing had happened to them so I decided to also go. That is why even when this trial came I wasn’t scared because I said even with COVID nothing happened when they tried the vaccine on us” (UG24, 31years, F) For some, seeing that rumours they heard about COVID-19 vaccines were not true in combination with increased knowledge of the process of vaccine development alleviated concerns about joining the study: “There is a way it helped me because before there were rumours that COVID-19 vaccines would kill people and that is not what happened. He mentioned more negative effects that would result from getting vaccinated with COVID and they were terrible, but when we got vaccinated, those things did not happen. Yet the vaccine was made very fast and not studied as those at MRC. In my thinking I said the vaccines tried through MRC are given time and even tried through animals and later people to make sure that they are safer” (UG5, 26years, F) One Ugandan participant did express concern regarding the plague vaccine sharing the same platform as the COVID-19 vaccine, worrying they could be vaccinated by stealth through the trial: “I just heard it when they talked about it, but I was not convinced because I was not vaccinated … It worried me because I said they could be wanting to vaccinate us through PlaVac. The way we had refused to be vaccinated” (UG1,26years,M) No participants in either study specifically discussed concerns about the risk of experiencing VITT. Discussion This study presents evidence of the impacts of the COVID-19 pandemic on healthy volunteers’ motivations and perceptions of a novel anti-plague vaccine, ChAdOx1 plague, from early-phase vaccine trials conducted in the UK and Uganda. The UK and Uganda PlaVac studies took place at different times in relation to the COVID-19 pandemic, and there were marked differences between the studies in the effect of the pandemic on motivations for volunteering. Fewer than a third of UK questionnaire participants agreed that the pandemic influenced their decision to volunteer, and most reported they would have participated in this kind of study pre-pandemic; which may be related to many of them being serial trial volunteers. In both questionnaire and interview responses the pandemic had either had no, or only minor, impact on UK participants’ volunteering motivations. By contrast, there was almost universal agreement amongst Uganda questionnaire participants that the pandemic had increased their awareness of vaccine trials; with 41.7% reporting they would not have volunteered before it. The Uganda interviews revealed a diversity of themes contributing to these responses. Participants’ experiences of living through the COVID-19 pandemic had left a marked impression of the vulnerability of society to unexpected epidemics; and not just the direct consequences of illness and death, but the social and economic disruption which came with non-pharmaceutical efforts to control COVID-19 in Uganda. 54-56 To counter this, participants felt that contributing to vaccine research by becoming a trial participant was an important way to protect themselves, their families, communities and nation from future harm. This sentiment echoes the views of volunteers for COVID-19 vaccine trials, who were strongly motivated by a wish to alleviate the suffering and harms being caused by the pandemic which they were living through; but is different in that PlaVac participants had no lived-experience of plague. 10, 20, 57, 58 An additional impact of the COVID-19 pandemic on participants volunteering for PlaVac Uganda was in the knock-on effect of education and awareness campaigns in relation to COVID-19 vaccination. The “Ekya COVID-19 Kijja Kugwa” (“COVID-19 Will Pass”) was a multimedia campaign launched in late 2021 and included information on vaccine safety and addressing vaccine hesitancy. 13 Many interviewees reported how learning about the process of vaccine development through COVID-19 campaigns had altered their perception of vaccine trials, and eased fears about participating in research. Another important factor was witnessing others be vaccinated without succumbing to any of the conditions that were rumoured to be caused by COVID-19 vaccines, such as death or infertility, which were common myths circulating in Uganda at the time. 59 This increased participants’ confidence that fears about receiving a study vaccine might also be unfounded. A unique factor of the PlaVac trials was that they were utilising the ChAdOx1 adenoviral-vector vaccine platform, at the same time that the ChAdOx1 nCoV-19 (Vaxzevria, AstraZeneca) was being used to vaccinate millions of people globally. 42 Despite widespread media coverage of the association of the related ChAdOx1 nCoV-19 with VITT, and being specifically counselled on the potential for VITT to be associated with ChAdOx1 Plague, participants in both UK and Uganda PlaVac studies reported that the investigational plague vaccine being similar to the COVID-19 vaccine increased their confidence in its safety. This might have been expected for the UK cohort, where over half had already been vaccinated with ChAdOx1 nCoV-19; but only eight of the Uganda cohort had received it and still were highly reassured by the similarity. No interviewees in either study mentioned concerns about blood clots, with only one UK interviewee alluding to negatives they had heard in the media, and despite many Uganda interviewees reporting that they had been COVID-19 vaccine-hesitant. Limitations There are some important limitations when considering these results. Whilst all efforts were made to modify the data collection tools to be linguistically and culturally appropriate for the Uganda study, the original versions were designed for the UK context, and questions may not have transposed well. Additionally, an important difference was the questionnaires being administered in the Uganda study, which may have increased social-desirability and courtesy bias in the results. 60 Not all study participants completed the mixed-methods procedures, with uptake particularly low in the UK study, which may have biased the results towards the opinions of a group of participants who had more positive experiences of participation. Relatively few UK participants participated in the interviews, and as the Uganda study sample size was pre-specified data saturation was not used to decide when to stop the semi-structured interviews. It is also important to note that the findings presented here on COVID-19 did not stand in isolation from other factors influencing participation such as altruism, trust, impact of study benefits and perceptions of risk, which are beyond the scope of this paper. Whilst these data provide insights as to the impact of the COVID-19 pandemic on the decision of individuals who volunteered for and were enrolled in a vaccine trial, it does not capture what the impact may have been on people who decided not to volunteer, or who withdrew during the screening process. Ultimately these data represent only the views of a small fraction of the general population, the majority of whom do not participate in clinical research. Conclusion Whilst the long-term impact of the pandemic on vaccine trials is as yet unknown, these data provide valuable insights as to the impact of COVID-19 on volunteers in studies of a novel plague vaccine, in both the UK and Uganda. These results suggest that there may be less of a “post-pandemic effect” in the high- than low-income setting in increasing vaccine trial participation. There was a noticeable difference in the effect of the pandemic as a motivator between studies, with both the experience of the COVID-19 pandemic and associated mass vaccination campaigns increasing Ugandan participants’ knowledge about vaccines and trials and encouraging them to participate in research. Additionally, these data are the first demonstrating the effect of the use of the ChAdOx1 nCoV-19 vaccine in mass vaccination campaigns, and healthy volunteers’ perception of receiving a related investigational vaccine Abbreviations COVID-19 - Coronavirus infectious disease 2019 WHO – World Health Organisation UK – United Kingdom Declarations Ethics approval and consent to participate This study was performed in line with the principles of the Declaration of Helsinki. Ethical approval for PlaVac was granted by South-Central Berkshire B Research Ethics Committee (REC) (ref:20/SC/0405). For PlaVac Uganda, approval was granted by the Oxford Tropical Research Ethics Committee (OxTREC Ref:19-22), the Uganda Virus Research Institute Research and Ethics Committee (ref:RGER220504), the Uganda National Council for Science and Technology (ref: HS2387ES); and the London School of Hygiene and Tropical Medicine (ref:28228). All participants provided written informed consent. Consent for publication All participants gave permission for direct quotations to be used. Availability of data and materials The datasets used and analysed during the current study are available from the corresponding author on reasonable request. Competing interests AJP is chair of the UK Department of Health and Social Care’s Joint Committee on Vaccination and Immunisation but did not participate in COVID19 vaccine policy during the pandemic. AJP, AS and CR are contributors to intellectual property licensed by Oxford University Innovation to AstraZeneca. The University of Oxford received funding from AstraZeneca to support the development of the Oxford-AstraZeneca COVID19 vaccine though the majority of the clinical development was funded by the UK Governmentr (NIHR), The Bill & Melinda Gates Foundation in South Africa and the Lehmann Foundation in Brazil. CSR has performed paid consultancy for Guidepoint. Funding The PlaVac trials were supported by Innovate UK, part of UK Research and Innovation (PlaVac [UK] grant number: 971510, PlaVac Uganda grant number: 10026240). The views expressed in this publication are those of the authors and not necessarily those of Innovate UK or DOH. The research in Uganda was conducted at the MRC/UVRI and LSHTM Uganda Research Unit which is jointly funded by the UK Medical Research Council (MRC) part of UK Research and Innovation (UKRI), and the UK Foreign, Commonwealth and Development Office (FCDO) under the MRC/FCDO Concordat agreement. 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SOCIAL DESIRABILITY BIAS IN CROSS‐CULTURAL ETHICS RESEARCH. The International Journal of Organizational Analysis 1993; 1: 185-202. DOI: 10.1108/eb028788. Additional Declarations Competing interest reported. AJP is chair of the UK Department of Health and Social Care’s Joint Committee on Vaccination and Immunisation but did not participate in COVID19 vaccine policy during the pandemic. AJP is a contributor to intellectual property licensed by Oxford University Innovation to AstraZeneca. The University of Oxford received funding from AstraZeneca to support the development of the Oxford-AstraZeneca COVID19 vaccine though the majority of the clinical development was funded by the UK Governmentr (NIHR), The Bill & Melinda Gates Foundation in South Africa and the Lehmann Foundation in Brazil. CSR has performed paid consultancy for Guidepoint. CSR is contributor to intellectual property licensed by Oxford University Innovation to AstraZeneca limited to COVID-19 applications. 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Oxford","correspondingAuthor":false,"prefix":"","firstName":"Denis","middleName":"","lastName":"Murphy","suffix":""},{"id":470386422,"identity":"9ba182d9-2e1d-4d10-8e78-4aaf332aae88","order_by":12,"name":"Samantha Vanderslott","email":"","orcid":"","institution":"University of Oxford","correspondingAuthor":false,"prefix":"","firstName":"Samantha","middleName":"","lastName":"Vanderslott","suffix":""},{"id":470386423,"identity":"0dc94741-d185-47bd-a46c-b08361e74f3a","order_by":13,"name":"Christine S Rollier","email":"","orcid":"","institution":"University of Surrey","correspondingAuthor":false,"prefix":"","firstName":"Christine","middleName":"S","lastName":"Rollier","suffix":""},{"id":470386424,"identity":"fbbe0488-90d1-4753-acae-910b42bc6820","order_by":14,"name":"Eugene Ruzagira","email":"","orcid":"","institution":"Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine, Uganda Research Unit, Uganda","correspondingAuthor":false,"prefix":"","firstName":"Eugene","middleName":"","lastName":"Ruzagira","suffix":""},{"id":470386426,"identity":"afc65c15-f7f6-4df5-8994-10b899983c68","order_by":15,"name":"Andrew J Pollard","email":"","orcid":"","institution":"University of Oxford","correspondingAuthor":false,"prefix":"","firstName":"Andrew","middleName":"J","lastName":"Pollard","suffix":""},{"id":470386428,"identity":"bde11c79-cbab-425a-96d0-fbb369c6a8fb","order_by":16,"name":"Nambusi Kyegombe","email":"","orcid":"","institution":"Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine, Uganda Research Unit, Uganda","correspondingAuthor":false,"prefix":"","firstName":"Nambusi","middleName":"","lastName":"Kyegombe","suffix":""}],"badges":[],"createdAt":"2025-05-13 17:38:04","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6657828/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6657828/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":84776988,"identity":"09dddab0-c9c1-490d-a3c3-ee5ebbe89711","added_by":"auto","created_at":"2025-06-17 09:07:24","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":165779,"visible":true,"origin":"","legend":"\u003cp\u003eResponses to Likert-type questions on motivations for volunteering for PlaVac studies. COVID-19 related motivations. UK (n=31), Uganda (n=36)\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6657828/v1/4ef83eb0dcd5ecaf1fedf52e.jpg"},{"id":84776987,"identity":"1f67789e-a7b1-4297-ba07-ed344267c48e","added_by":"auto","created_at":"2025-06-17 09:07:24","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":185087,"visible":true,"origin":"","legend":"\u003cp\u003eResponses to Likert-type questions on ChAdOx1 plague and relationship to ChAdOx1 nCoV-19 (Vaxzevria, AstraZeneca) vaccine. UK (n=31), Uganda (n=36)\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6657828/v1/d49d64a886cb622e6dd96998.jpg"},{"id":84781118,"identity":"410e638e-a8ad-4dce-ad3c-467da7a94627","added_by":"auto","created_at":"2025-06-17 09:31:25","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1594438,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6657828/v1/29be741a-8491-4347-8665-5ac762ebd50b.pdf"},{"id":84776986,"identity":"580c4c1d-65b5-4c83-9ad9-00c9456d2560","added_by":"auto","created_at":"2025-06-17 09:07:24","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":72396,"visible":true,"origin":"","legend":"","description":"","filename":"COVID19motivations130525submissioncopysupps.docx","url":"https://assets-eu.researchsquare.com/files/rs-6657828/v1/e45086b06a50de33c8e2b6f1.docx"}],"financialInterests":"Competing interest reported. AJP is chair of the UK Department of Health and Social Care’s Joint Committee on Vaccination and Immunisation but did not participate in COVID19 vaccine policy during the pandemic. AJP is a contributor to intellectual property licensed by Oxford University Innovation to AstraZeneca. The University of Oxford received funding from AstraZeneca to support the development of the Oxford-AstraZeneca COVID19 vaccine though the majority of the clinical development was funded by the UK Governmentr (NIHR), The Bill \u0026 Melinda Gates Foundation in South Africa and the Lehmann Foundation in Brazil. CSR has performed paid consultancy for Guidepoint. CSR is contributor to intellectual property licensed by Oxford University Innovation to AstraZeneca limited to COVID-19 applications.","formattedTitle":"The impact of the COVID-19 pandemic on healthy volunteer motivations: a mixed-methods study of participants in plague vaccine trials in the UK and Uganda","fulltext":[{"header":"Background","content":"\u003cp\u003eThe COVID-19 pandemic of 2020-2023 was a global health crisis unprecedented in modern times, with seven million direct deaths, an excess mortality rate of two to four times this, and associated profound economic and social disruption.\u003csup\u003e\u0026nbsp;1-6\u003c/sup\u003e This prompted a global race to develop vaccines, with over 288 trials registered between 2020-2021.\u003csup\u003e\u0026nbsp;7\u003c/sup\u003e These trials took place in the context of what the World Health Organisation (WHO) described as an “infodemic” of information and misinformation, in addition to countries’ own awareness and health campaigns, and whilst at the time there was a surge in interest vaccine trial volunteering, there was also a rise in vaccine hesitancy, which has persisted beyond the pandemic.\u003csup\u003e\u0026nbsp;8-13\u003c/sup\u003e Early-phase vaccine trials rely on recruiting “healthy volunteers”; people who usually do not stand to benefit from the study intervention, and run the risk of incurring harm from study procedures or adverse reactions\u003csup\u003e14, 15\u003c/sup\u003e. Healthy volunteers' motivations to participate in vaccine trials are less well studied than those for non-vaccine drug trials, but \u0026nbsp;in diverse income settings have been found to encompass altruistic motivations, desires to contribute to science and financial and non-financial benefits of participation.\u003csup\u003e\u0026nbsp;16-18\u003c/sup\u003e Evidence from studies of COVID-19 trial volunteers in both high- and low-income countries suggests differences to pre-pandemic volunteers, with motivations directly linked to contributing to a mitigation of the social and individual suffering caused by the pandemic, and a sense of urgency for the need to take action in the face of a pressing health crisis.\u003csup\u003e\u0026nbsp;10, 19-21\u003c/sup\u003e Participant motivation is an important aspect of trial participation as it affects recruitment, informed consent, and retention.\u003csup\u003e\u0026nbsp;18, 22-26\u003c/sup\u003e For example, high financial compensation can over-incentivise participation leading volunteers to enrol in trials without due consideration of potential risks, potentially invalidating the concept of informed consent.\u003csup\u003e\u0026nbsp;27, 28\u003c/sup\u003e. Non-financial compensation such as free healthcare during study participation has been noted to be particularly incentivising in low-resource settings.\u003csup\u003e\u0026nbsp;29-32\u003c/sup\u003eWhat is not yet known is whether the COVID-19 pandemic influenced the decision to volunteer \u0026nbsp;for participants in non-COVID-19 vaccine trials, many of which were delayed or suspended during the acute phase of the pandemic in 2020-2021.\u003csup\u003e\u0026nbsp;33\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eWhilst COVID-19 is the most recent pandemic of modern times, plague, a lethal disease caused by the bacterium \u003cem\u003eYersinia pestis\u003c/em\u003e, tends to be considered a historical disease.\u003csup\u003e\u0026nbsp;34\u003c/sup\u003eThis is unfortunately a misconception, as plague is globally distributed in endemic foci, and is classified as a “re-emerging” disease with up to 700 cases annually.\u003csup\u003e\u0026nbsp;35, 36\u003c/sup\u003e Despite this, there is no licenced vaccine approved by the WHO.\u003csup\u003e\u0026nbsp;34, 37\u003c/sup\u003e Over 90% of annual cases occur in rural and medically underserved communities in sub-Saharan Africa, including Uganda which contains both endemic foci in Northern regions and is vulnerable to cross-border transmission from the Democratic Republic of Congo.\u003csup\u003e\u0026nbsp;38, 39\u003c/sup\u003e Efforts to develop a modern vaccine have thus far failed.\u003csup\u003e\u0026nbsp;40\u003c/sup\u003e A novel plague vaccine, ChAdOx1 Plague, has been developed by the University of Oxford and underwent Phase I testing in two trials, the first (PlaVac) in Oxford, United Kingdom (UK) starting in late 2021, and the second (PlaVac Uganda) in Masaka, Uganda in early 2022. These trials were positioned in a unique context; both studies began enrolling participants after the commencement of mass COVID-19 vaccination campaigns and the easing of non-pharmaceutical interventions (e.g. social distancing) in their respective countries, and the trial vaccine is closely related to the ChAdOx1 nCoV-19 vaccine (Vaxzevria, AstraZeneca) which had been extensively used in COVID-19 vaccination campaigns in both countries. \u003csup\u003e41-45\u003c/sup\u003e Additionally, recruitment for both studies took place after there had been pauses in multiple countries’ use of the vaccine due to the occurrence of fatal blood clotting events; what later became known as vaccine-induced immune thrombocytopenia and thrombosis (VITT), which garnered extensive media coverage, including in Uganda – and at the time it was unknown what impact this would have on recruitment.\u003csup\u003e\u0026nbsp;46-51\u003c/sup\u003e As part of the PlaVac trials, mixed-methods study procedures comprising a questionnaire and semi-structured interview examining the volunteering motivations and experiences of trial participants were conducted. Data showing the impact of the COVID-19 pandemic on participants motivations and trial experience will be presented here.\u003c/p\u003e"},{"header":"Methods","content":"\u003ch2\u003eStudy setting and population\u003c/h2\u003e\n\u003cp\u003eMixed-methods study procedures were included in two phase I studies of an investigational plague vaccine, ChAdOx1 Plague. PlaVac (ISRCTN:41077863) was a Phase Ia trial conducted at the Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK, and PlaVac Uganda (ISRCTN:79243381) a Phase Ib trial conducted by Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit field station in Masaka, Southwestern Uganda, where plague is not present. The primary endpoint of both Phase I trials was the safety and tolerability of ChAdOx1 Plague in healthy adults. To be eligible for participation in the PlaVac trials, volunteers had to provide written informed consent, be considered medically healthy, not pregnant or lactating, and adherent to contraception for the duration of the trial. Age inclusion criteria were 18-55 years for the UK study and 18-49 years for the Uganda study. The lower inclusion age-range for the Uganda study was based on the progress of the Uganda COVID-19 vaccination rollout at the time of study design, with the decision to exclude the most prioritised over 50 age group, due to the risk of discencentivising take up of COVID-19 vaccination through study participation as there were temporal exclusions around receiving other vaccines once enrolled in the study.\u003c/p\u003e\n\u003ch2\u003eStudy design, sampling, and sample size\u003c/h2\u003e\n\u003cp\u003eFor mixed-methods procedures a \u0026nbsp;convergent parallel design was used. Quantitative and qualitative data were collected concurrently, analysed independently and combined in interpretation.\u003csup\u003e\u0026nbsp;52\u003c/sup\u003e Participation in mixed-methods procedures was optional in both studies. For the PlaVac UK study, all participants were invited to complete the questionnaire, with the optional additional completion of an in-depth interview using a semi-structured guide. For PlaVac Uganda, all participants were invited to complete the questionnaire, and optionally the interview. Participants who wished to complete an interviews were purposively sampled, aiming to include equal numbers of males and females. All participants were reimbursed for study visits, to cover transport and time expenses, as per local guidelines. Participants had received information on plague via study information-giving sessions (Uganda only) and via the participant information sheet and informed consent process.Data collection and analysis\u003c/p\u003e\n\u003cp\u003eFor the quantitative component, a 47-item questionnaire was developed based on the literature review, and experience of conducting a survey of COVID-19 trial volunteers (Supplementary Table 1 and Supplementary Table 2).\u003csup\u003e10\u003c/sup\u003e Questionnaire domains included demographics, previous experience of clinical trials, attitudes to blood and organ donation, motivations for volunteering for the study, views on risks of the study and experiences of study participation. \u0026nbsp;The questionnaire was reviewed by the PlaVac Uganda study team, with modification of questions for cultural appropriateness. Both questionnaire versions were piloted with local teams before finalisation.\u003c/p\u003e\n\u003cp\u003eQuestionnaire data were collected in JISC Online Surveys V2. UK participants completed questionnaires in privacy via a single-use URL sent by the study team. UK responses were pseudo-anonymised through an embedded token in the email link, meaning data was extractable from the survey platform in a fully anonymised format, but participant responses could be tracked. Uganda questionnaires were administered by a researcher who was not previously known to the participant or part of the clinical team, with direct data entry using a laptop. There was no linkage of identifiers between mixed-methods procedures and the main study data. Data were analysed descriptively using StataSE V18.0 (StataCorp, Texas, USA) and Microsoft Excel (v2404).\u003c/p\u003e\n\u003cp\u003eFor the qualitative data, an interview guide was developed based on questionnaire domains, using pre-scripted open-ended questions and prompts, and was reviewed and modified by the Uganda study team for use in PlaVac Uganda (Supplementary Table 3, Supplementary Table 4). The guide was piloted among staff at both study sites who were not familiar with the study, to ensure flow and comprehensibility of the prompts. UK in-depth interviews were conducted via video call (Microsoft Teams) by a researcher not previously known to the participant. Uganda the in-depth interviews were conducted in person after questionnaire administration, by the same researcher who conducted the questionnaire. Interviews were conducted in Luganda transcribed verbatim in English and organised using Nvivo 12 Pro (QSR International). Transcripts were fully coded, with codes generated using inductive and deductive approaches. For the Uganda data, transcripts were coded by two researchers, with iterative development of the codebook. \u0026nbsp;Thematic analysis was conducted to generate themes and code the data.\u003csup\u003e\u0026nbsp;53\u003c/sup\u003e\u003c/p\u003e"},{"header":"Results","content":"\u003ch2\u003eParticipants\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eEnrolment to PlaVac UK took place between August and October 2021, with 45 participants, and enrolment to PlaVac Uganda in March 2022, with 36 participants. \u0026nbsp;Thirty-one of the 45 PlaVac UK participants completed the optional questionnaire, and nine of those the interview. All 36 PlaVac Uganda participants completed the optional questionnaire, and 19 of those completed an interview.\u0026nbsp;\u003c/p\u003e\n\u003ch3\u003eDemographics of questionnaire participants\u003c/h3\u003e\n\u003cp\u003eThere was a higher proportion of questionnaire participants in younger age categories in Uganda than in the UK, with 72.2% vs 48.4% falling in 18-34 years. Both samples were \u0026gt;70.0% male, which was reflective of the overall study composition (Supplementary Table 5). Uganda participants were predominantly of Christian religions (86.1%), whereas most UK participants had no religion (64.5%). Over half of the Uganda cohort had received only primary education (52.8%), whereas 64.5% of the UK cohort had a university degree. Most participants in both studies were employed (for Uganda participants, employed was defined as having done work in the past 7 days), 94.4% vs 83.9% in Uganda and UK, respectively. UK participants were more likely to be experienced trial volunteers, with 54.8% (n=17) having previously been in a clinical trial, versus 5.6% (n=2) of the Uganda participants. All UK participants had completed at least eight of the 12 months of study follow-up, and Uganda participants had completed at least five of the seven months. (Table 1)\u003c/p\u003e\n\u003ch3\u003eDemographics of interview participants\u003c/h3\u003e\n\u003cp\u003eDue to purposive sampling, the Uganda participants had more even gender balance, whereas UK remained with a male preponderance (66.7%). Older participants were over-represented in UK interviewees, and Uganda interviewees\u0026rsquo; ages were more similar to the questionnaire cohort, with the largest age group being 25-34 years. (Table 2)\u003c/p\u003e\n\u003cp\u003eTable 1. Demographics of PlaVac UK and Uganda questionnaire participants.\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eUK (N=31)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eUganda (N=36)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003en (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;n (%) \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge category\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e18-24 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e8 (25.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e13 (36.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e25-34 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e7 (22.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e13 (36.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e35-44 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e6 (19.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e9 (25.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e45-49/55* years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e10 (32.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (2.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eGender\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e22 (71.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e26 (72.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e8 (25.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e10 (27.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eOther\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eReligion\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo religion\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e20 (64.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eChristian~\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e10 (32.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e31 (86.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMuslim\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e5 (13.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eOther religion\u003csup\u003e#\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eEthnicity\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWhite - British\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e27 (87.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWhite - Other\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed - White and Black Caribbean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed - Other\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePrefer not to say\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBlack African\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e36 (100.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eEducation^\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePrimary\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;(-)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e19 (52.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSecondary school/ up to 16 years (UK)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e13 (36.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eHigher secondary/further education/more than secondary\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e10 (32.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e4 (11.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eUniversity bachelor\u0026apos;s degree\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e11 (35.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePostgraduate degree\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e9 (29.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eEmployment status\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eEmployed full time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e20 (64.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e34 (94.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eEmployed part time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eUnemployed and currently looking for work\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2 (5.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eStudent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eHomemaker\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSelf-employed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eType of employment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eEducation, law, social, government services\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e6 (19.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2 (5.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eHealth\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e5 (16.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (2.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBusiness/Finance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e6 (16.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCarer for other household member\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (2.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSales and services\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e6 (16.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eManagement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNatural/applied science\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eStudent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eOther\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e4 (12.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTrades and transport\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e12 (33.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCraft and related trades\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (8.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAgriculture\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e4 (11.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMarital status\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSingle (never married)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e13 (41.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e17 (47.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMarried\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e7 (22.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e14 (38.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSeparated\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (8.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCohabiting\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e7 (22.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDivorced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (2.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePrefer not to say\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (3.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWidowed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (2.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eNumber of children\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e18 (58.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e10 (27.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eOne\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e5 (16.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e7 (19.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTwo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e6 (19.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e4 (11.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eThree\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2 (6.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2 (5.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eFour\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e6 (16.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eFive\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2 (5.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSix\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2 (5.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSeven\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (2.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eEight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (2.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePrefer not to say\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1 (2.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eHousehold income\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eLess than \u0026pound;15,000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2 (6.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026pound;15,000 - \u0026pound;24,999\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026pound;25,000 - \u0026pound;54,999\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e6 (19.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026pound;55,000 - \u0026pound;99,999\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e11 (35.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026pound;100,000 - \u0026pound;149,999\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e5 (16.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026pound;150,000 or more\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2 (6.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePrefer not to say\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2 (6.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eHave you ever been in another study before this one?\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e17 (54.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2 (5.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e14 (45.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e34 (94.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e* Upper inclusion age range UK/Uganda\u003c/p\u003e\n \u003cp\u003e~includes Catholic, Protestant and all other Christian denominations\u003c/p\u003e\n \u003cp\u003e#\u0026ldquo;Agnostic\u0026rdquo; free-text\u003c/p\u003e\n \u003cp\u003e^Education includes completion of any grade within that category\u003c/p\u003e\n \u003cp\u003e$Includes vocational and professional training\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eTable 2. Demographics of PlaVac UK and Uganda interview participants\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eUK (n=9)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eUganda (n=19)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eGender\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003en (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003en (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6 (66.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10 (52.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2 (22.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9 (47.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNon-binary\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1 (11.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge category\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e18-24 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2 (22.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5 (26.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e25-34 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9 (47.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e35-44 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2 (22.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5 (26.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e45-55/49* years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5 (55.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eReligion\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eChristian\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e13 (68.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMuslim\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5 (26.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNot given\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1 (5.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eEducation^\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePrimary\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11 (57.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSecondary\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4 (21.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMore than secondary^^\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4 (21.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cul\u003e\n \u003cli\u003eCategory not collected for either study\u003c/li\u003e\n \u003c/ul\u003e\n \u003cp\u003e*Upper limit 55years for UK and 49 for Uganda at time of enrolment\u003c/p\u003e\n \u003cp\u003e^Education includes completion of any grade within that category\u003c/p\u003e\n \u003cp\u003e^^Includes vocational and professional training\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003ch2\u003eImpact of the COVID-19 pandemic on decision to volunteer for the trial\u003c/h2\u003e\n\u003cp\u003eParticipants in both studies were asked about the impact of the COVID-19 pandemic on their decision to volunteer for the PlaVac trials (Figure 1). When asked about the impact of the pandemic on their awareness of clinical trials, and whether this influenced their volunteering decision, fewer than a third of UK respondents (30.6%, n=11) overall agreed, versus 97.2% (n=35) of the Ugandan participants. UK participants also generally disagreed with the statement \u003cem\u003e\u0026ldquo;Before the COVID-19 pandemic I would not have volunteered for this kind of study\u0026rdquo;\u0026nbsp;\u003c/em\u003eat 74.2% (n=23), whereas Ugandan participants gave mixed responses with 47.2% (n=17) overall agreeing, 41.7% (n=15) overall disagreeing, \u0026nbsp;and 11.1% (n=4) being neutral.\u003c/p\u003e\n\u003cp\u003eIn keeping with questionnaire responses, UK interviewees did not spontaneously mention the pandemic as having been a motivator. When probed by the interviewer, it was described as either having no impact at all, or as a contributing, but not definitive motivator:\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;I don\u0026rsquo;t know if I would have taken part before [the COVID-19 pandemic], or not taken part, I think, but I think this [the pandemic] definitely pushed me towards a yes, I should take part in a vaccine study\u0026rdquo;. \u0026nbsp;(UK05, 45-55years)\u003c/p\u003e\n\u003cp\u003eA single participant described how it has increased his interest in the process of vaccine development:\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;through the pandemic, it was like a chance where I wanted to try and help out, so I signed up to the St. John\u0026apos;s [St.John\u0026rsquo;s Ambulance Service \u0026ndash; voluntary healthcare organisation assisting with vaccinations]to become a vaccinator, to try and expose myself to more of like the clinical side. And I was interested in how vaccines come from being discovered, to going through trials, to being manufactured, and then delivered. I thought the best way to learn was if I could put myself in the different steps and see it from the inside, so it sort of played a part, yes.\u0026rdquo;\u0026nbsp;(UK08, 18-24years, M)\u003c/p\u003e\n\u003cp\u003eUganda interviewees prominently described COVID-19 as having been a motivator, which could be grouped under themes of \u0026ldquo;preparedness\u0026rdquo;, \u0026ldquo;increased awareness\u0026rdquo; and \u0026ldquo;personal experience\u0026rdquo;.\u003c/p\u003e\n\u003ch4\u003ePreparedness \u0026ndash; \u0026ldquo;COVID-19 killed many people\u0026rdquo;\u003c/h4\u003e\n\u003cp\u003eParticipants drew a parallel between the abrupt onset and high mortality of the COVID-19 pandemic and the potential for another disease without a ready vaccine, such as plague, to do the same. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;COVID-19 killed so many people and it also motivated me to participate in the plague vaccine trial to get medication that can help people if there is an outbreak \u0026hellip; If there is an outbreak of plague without medication, it can also kill so many people as COVID-19 did. \u0026rdquo;\u0026nbsp;(UG34, 25years, M)\u003c/p\u003e\n\u003cp\u003eSome participants drew a specific link between the risk of being unprepared for an epidemic, and the continued presence of plague in Uganda:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;Interviewer: do think Plague is a big problem in Uganda or it is not?\u003c/p\u003e\n\u003cp\u003eInterviewee: It is not a big problem because of the low number affected by it but if it gets worse it can be trouble in case we have no vaccine. That is why a vaccine is needed so that we do not get other things like COVID which got us not prepared. Because all is possible\u0026rdquo; \u0026nbsp;(UG5, 26years, F)\u003c/p\u003e\n\u003cp\u003eAnother element of preparedness was the need to have a vaccine to avoid the use of non-pharmaceutical disease control interventions that caused so much economic and social hardship:\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;It motivated me greatly because the situation was not easy and the way the disease [COVID-19] broke out in a way we did not understand\u0026hellip;first we were locked down and not free to move from our places to go to other places. The finances were greatly affected and the disease also claimed a lot of lives every day. Item prices increased rapidly. When someone coughed it would worry you and cause you to distance from them. In case you saw a stranger in the village you would worry about him, you would wonder what they are looking for, we did not want anyone coming to our home\u0026rdquo;\u0026nbsp;(UG29, 35years, F)\u003c/p\u003e\n\u003ch4\u003eIncreased awareness \u0026ndash; \u0026ldquo;It opened people\u0026rsquo;s eyes\u0026rdquo;\u003c/h4\u003e\n\u003cp\u003eMatching the questionnaire responses, many Ugandan interviewees reported the COVID-19 pandemic had increased their knowledge of the process of vaccine development and clinical trials, and this had positively influenced their decision to volunteer. Interviewees reported being sensitised through COVID-19 vaccination information campaigns on television and radio, which had increased their confidence, enabling them to act on their desire to contribute to the protection of their communities:\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;COVID scared me and I refused to get vaccinated. It was during COVID that I heard on the radio about the process of first trying the vaccine on animals and later on people. I heard that on the radio before coming here for the study. When the study came into my community it helped me to understand more and I decided to participate because it helped me to learn to contribute. After all, you or your family could get that disease or anyone in the community. Like the way COVID broke out in the community. So, I decided to participate so that researchers can do their best as we contribute through participation\u0026rdquo; (UG25, 36years, F)\u003c/p\u003e\n\u003cp\u003eThis increased knowledge and awareness also affected participants\u0026rsquo; perception of the safety of vaccine trials, both through being told about the development process, and through witnessing others be safely vaccinated:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;Yes, it opened people\u0026rsquo;s eyes to understand that trying vaccines on you does not kill you. As they used to think about it. Because even the COVID-19 vaccine had been tried on people in a short time\u0026rdquo;\u0026nbsp;(UG11, 26years,F)\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;Interviewer: Do you think COVID increased awareness about vaccine trials?\u003c/p\u003e\n\u003cp\u003eInterviewee: Yes sir, It greatly contributed to vaccine trial awareness because I expect that all that accepted to participate in this study greatly relied on that. And the time they sent us the COVID vaccine, you would know that there are also people who stood in for us or who surrendered themselves to get the vaccine. It was equally tried on people. They just did not get it out of the blue and injected it in people. And we did not get news that when that vaccine was tried on a group of people in a particular area they were harmed. We did not get that kind of news\u0026rdquo; (UG29, 35years, F)\u003c/p\u003e\n\u003ch4\u003ePersonal protection \u0026ndash; \u0026ldquo;I will be safe\u0026rdquo;\u003c/h4\u003e\n\u003cp\u003eParticipants are explicitly counselled during the consent process that the vaccine is new, and it is unknown whether it would offer any protection against plague disease. However, in both interviews and free-text responses to the questionnaire, some participants (both young and old) were motivated to participate because they believed receiving the novel plague vaccine would protect them from a future outbreak. This need for personal protection was also explicitly linked to their experiences of the COVID-19 pandemic:\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;My major reason was COVID-19 because I heard it affected many people and many died so I decided to also get vaccinated because in case of an outbreak. We were told the plague had broken out before. I went and asked my elder sibling who also told me the plague was here in the early days. I thought if I take this opportunity to get vaccinated even when it breaks out, I will be safe\u0026rdquo;(UG25,36y, F)\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;To see that I help others and also help myself by getting a vaccine to prevent myself from getting plague \u0026hellip; The reason for the way I saw people dying and the condition in which they were living. Indeed, and when a chance came and there was a trial, I said let me give in myself to try this in that even when this breaks out. I can survive it\u0026rdquo;\u0026nbsp;(UG36, 29years, M)\u003c/p\u003e\n\u003cp\u003eWhilst most participants describing \u0026ldquo;personal protection\u0026rdquo; felt it was likely the vaccine would be effective, a few were aware that it could fail, but still felt it was worth having:\u003c/p\u003e\n\u003cp\u003e\u0026lsquo;\u0026rsquo;I was greatly motivated by the fact that back in the day we had been hit by COVID. The situation we went through was not good. Now when they taught us about participating in studies, it\u0026rsquo;s the truth that someone has got to fight for themselves and also fight for his nation...If the vaccine gets to be successful. It will have saved me and also save others.\u0026rsquo;\u0026rsquo;\u0026nbsp;(UG29, 35y, F)\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;The other thing is that I expected that if I come and God helps me and this vaccine succeeds it means that even when Plague breaks out. I will not be worried because I will be aware that I was vaccinated. If this vaccine works my body will be able to have the antibodies that fight plague\u0026rdquo;\u0026nbsp;(UG22, 23y, M)\u003c/p\u003e\n\u003ch2\u003eTwo plagues, two vaccines \u0026ndash; ChAdOx1-nCoV-19 and ChAdOx1 Plague\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eAt the time of enrolment, all PlaVac UK participants had received at least one dose of COVID-19 vaccine, versus 30.6% of PlaVac Uganda participants. Over half of the UK participants had received ChAdOx1-nCoV-19, as had 62.5% of Uganda participants who had received a COVID-19 vaccination (Supplementary Table 5). The vaccination status of the questionnaire and interviewparticipants was not specifically recorded, but some participants discussed their COVID-19 vaccination status at interview.\u003c/p\u003e\n\u003cp\u003eParticipants were asked about their perception of the safety of the plague study vaccine in relation to its similarity to the ChAdOx1-nCoV-19 (Vaxzevria,AstraZeneca) COVID-19 vaccine (Figure 2). In both studies,this similarity was reassuring, with 67.7% (n=21) of UK participants and 80.6% (n=29) of Ugandan participants overall agreeing that this made them feel the study vaccine was likely to be safe. When asked whether they worried about the risk of vaccine-induced thrombosis with thrombocytopenia (VITT, described to participants as blood clots related to the vaccine) in both studies relatively small proportions agreed they had concerns, at 16.1% (n=5) of UK participants and 22.2% (n=8) of Ugandan participants.\u003c/p\u003e\n\u003cp\u003eInterview responses from both studies elucidated reasonings behind responses on the link between the two ChAdOx1 vaccines and the perceived risk of the trial, with themes of \u0026ldquo;safer because ChAdOx1\u0026rdquo; and \u0026ldquo;negative press and rumours\u0026rdquo; emerging.\u003c/p\u003e\n\u003ch4\u003eSafer because ChAdOx1 \u0026ndash; \u0026ldquo;it\u0026rsquo;s the same thing\u0026rdquo;\u003c/h4\u003e\n\u003cp\u003eAs with the questionnaire responses, many interviewees in UK and Uganda studies drew a link between the use of ChAdOx1-nCoV-19 as a pandemic vaccine, and the potential riskiness of the plague trial vaccine; with most participants feeling that this made it safer. In keeping with the difference in proportions previously vaccinated with ChAdOx1 nCoV-19 between the two studies, UK interviewees were more likely to link the experience of being personally ChAdOx1 nCoV-19 vaccinated with the perception of safety, whereas Uganda participants were more likely to report witnessing its use in their communities as the reassuring factor; although some interviewees had been also vaccinated with ChAdOx1 and also found this personally reassuring . \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;I had previously had a ChAdOx1 vaccine against COVID, so obviously, so there\u0026apos;s one thing there which is sort of like, you know, I have been injected with this vector before. So that\u0026apos;s a few of the things that you might imagine that might go wrong, that you could, that even just for me, I have had experience of having that vaccination so, you know, I\u0026apos;m thinking I look, I was looking at it, as this is a sort of, this is basically a fairly similar vaccination with a slightly different bit of... A slightly different bit pasted in. So I was assuming the risk was fairly low\u0026rdquo;\u0026nbsp;(UK06, 45-55years, M)\u003c/p\u003e\n\u003ch4\u003e\u0026ldquo;It made me stronger in a way that if the vaccine is in any way related to that of COVID. Those vaccinated against COVID are many and I did not hear that someone died because of getting vaccinated\u0026rdquo;\u0026nbsp;(UG29, 35y, F)Negative press and rumours \u0026ndash; \u0026ldquo;these things did not happen\u0026rdquo;\u003c/h4\u003e\n\u003cp\u003eOnly a single participant, in the UK study, mentioned hearing about negative events related to the ChAdOx1-nCoV-19 vaccine in the media, but this did not affect their confidence that the vaccine platform would be safe:\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;Like I don\u0026apos;t believe I\u0026apos;ll be an anomaly [have a rare side effect]. I don\u0026apos;t think I\u0026apos;ll have adverse reactions to it. So I didn\u0026apos;t, I don\u0026apos;t think I ever really thought that it was a bad thing that it was based off of that, due to that history [of episodes of VITT reported in media]. I thought it was more of a good thing because it\u0026apos;s based off of that [ChAdOx1 vaccine platform], and that that\u0026apos;s something that\u0026apos;s been working, you know? ... So I don\u0026apos;t think it made me think any worse of it just because of what media has said because you can\u0026apos;t trust everything in the media\u0026rdquo; (UK03, 18-24years,F)\u003c/p\u003e\n\u003cp\u003eParticipants in the Uganda study did report rumours they had heard about COVID-19 vaccination, and many had been personally afraid of being vaccinated:\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;We were scared of death. We were suspicious of the vaccine.\u0026rdquo;\u0026nbsp;(UG35,40years, M)\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The most common rumours were that the vaccine would kill you, or would cause sterility and was a method of population control:\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;I thought that the vaccine would kill me. Okay at first we were so fearful. You could think that what if they inject me and the vaccine is aimed at reducing on the number of people in the country\u0026rdquo;\u0026nbsp;(UG01,26years,M)\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Key in alleviating fears about COVID-19 vaccination was witnessing others not experience adverse effects from vaccination, and this gave confidence to participate in the PlaVac trial:\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;\u0026hellip;for COVID-19 I was even scared of the injection [vaccine] as people said the moment you get the injection you are going to die. My children went first for that vaccine but when they came back home I saw that nothing had happened to them so I decided to also go. That is why even when this trial came I wasn\u0026rsquo;t scared because I said even with COVID nothing happened when they tried the vaccine on us\u0026rdquo;\u0026nbsp;(UG24, 31years, F)\u003c/p\u003e\n\u003cp\u003eFor some, seeing that rumours they heard about COVID-19 vaccines were not true in combination with increased knowledge of the process of vaccine development alleviated concerns about joining the study:\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;There is a way it helped me because before there were rumours that COVID-19 vaccines would kill people and that is not what happened. He mentioned more negative effects that would result from getting vaccinated with COVID and they were terrible, but when we got vaccinated, those things did not happen. Yet the vaccine was made very fast and not studied as those at MRC. In my thinking I said the vaccines tried through MRC are given time and even tried through animals and later people to make sure that they are safer\u0026rdquo;\u0026nbsp;(UG5, 26years, F)\u003c/p\u003e\n\u003cp\u003eOne Ugandan participant did express concern regarding the plague vaccine sharing the same platform as the COVID-19 vaccine, worrying they could be vaccinated by stealth through the trial:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;I just heard it when they talked about it, but I was not convinced because I was not vaccinated \u0026hellip; It worried me because I said they could be wanting to vaccinate us through PlaVac. The way we had refused to be vaccinated\u0026rdquo;\u0026nbsp;(UG1,26years,M)\u003c/p\u003e\n\u003cp\u003eNo participants in either study specifically discussed concerns about the risk of experiencing VITT.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study presents evidence of the impacts of the COVID-19 pandemic on healthy volunteers’ motivations and perceptions of a novel anti-plague vaccine, ChAdOx1 plague, from early-phase vaccine trials conducted in the UK and Uganda.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe UK and Uganda PlaVac studies took place at different times in relation to the COVID-19 pandemic, and there were marked differences between the studies in the effect of the pandemic on motivations for volunteering. Fewer than a third of UK questionnaire participants agreed that the pandemic influenced their decision to volunteer, and most reported they would have participated in this kind of study pre-pandemic; which may be related to many of them being serial trial volunteers. In both questionnaire and interview responses the pandemic had either had no, or only minor, impact on UK participants’ volunteering motivations. By contrast, there was almost universal agreement amongst Uganda questionnaire participants that the pandemic had increased their awareness of vaccine trials; with 41.7% reporting they would not have volunteered before it. The Uganda interviews revealed a diversity of themes contributing to these responses. Participants’ experiences of living through the COVID-19 pandemic had left a marked impression of the vulnerability of society to unexpected epidemics; and not just the direct consequences of illness and death, but the social and economic disruption which came with non-pharmaceutical efforts to control COVID-19 in Uganda.\u003csup\u003e\u0026nbsp;54-56\u003c/sup\u003e To counter this, participants felt that contributing to vaccine research by becoming a trial participant was an important way to protect themselves, their families, communities and nation from future harm. This sentiment echoes the views of volunteers for COVID-19 vaccine trials, who were strongly motivated by a wish to alleviate the suffering and harms being caused by the pandemic which they were living through; but is different in that PlaVac participants had no lived-experience of plague.\u003csup\u003e\u0026nbsp;10, 20, 57, 58\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAn additional impact of the COVID-19 pandemic on participants volunteering for PlaVac Uganda was in the knock-on effect of education and awareness campaigns in relation to COVID-19 vaccination. The “Ekya COVID-19\u0026nbsp;Kijja Kugwa” (“COVID-19 Will Pass”) was a multimedia campaign launched in late 2021 and included information on vaccine safety and addressing vaccine hesitancy.\u003csup\u003e\u0026nbsp;13\u003c/sup\u003e\u0026nbsp; Many interviewees reported how learning about the process of vaccine development through COVID-19 campaigns had altered their perception of vaccine trials, and eased fears about participating in research. Another important factor was witnessing others be vaccinated without succumbing to any of the conditions that were rumoured to be caused by COVID-19 vaccines, such as death or infertility, which were common myths circulating in Uganda at the time.\u003csup\u003e\u0026nbsp;59\u003c/sup\u003e This increased participants’ confidence that fears about receiving a study vaccine might also be unfounded.\u003c/p\u003e\n\u003cp\u003eA unique factor of the PlaVac trials was that they were utilising the ChAdOx1 adenoviral-vector vaccine platform, at the same time that the ChAdOx1 nCoV-19 (Vaxzevria, AstraZeneca) was being used to vaccinate millions of people globally.\u003csup\u003e\u0026nbsp;42\u003c/sup\u003e\u0026nbsp; Despite widespread media coverage of the association of the related ChAdOx1 nCoV-19 with VITT, and being specifically counselled on the potential for VITT to be associated with ChAdOx1 Plague, participants in both UK and Uganda PlaVac studies reported that the investigational plague vaccine being similar to the COVID-19 vaccine increased their confidence in its safety. This might have been expected for the UK cohort, where over half had already been vaccinated with ChAdOx1 nCoV-19; but only eight of the Uganda cohort had received it and still were highly reassured by the similarity. No interviewees in either study mentioned concerns about blood clots, with only one UK interviewee alluding to negatives they had heard in the media, and despite many Uganda interviewees reporting that they had been COVID-19 vaccine-hesitant.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003eLimitations\u003c/h2\u003e\n\u003cp\u003eThere are some important limitations when considering these results. Whilst all efforts were made to modify the data collection tools to be linguistically and culturally appropriate for the Uganda study, the original versions were designed for the UK context, and questions may not have transposed well. Additionally, an important difference was the questionnaires being administered in the Uganda study, which may have increased social-desirability and courtesy bias in the results.\u003csup\u003e\u0026nbsp;60\u003c/sup\u003e\u0026nbsp; Not all study participants completed the mixed-methods procedures, with uptake particularly low in the UK study, which may have biased the results towards the opinions of a group of participants who had more positive experiences of participation. Relatively few UK participants participated in the interviews, and as the Uganda study sample size was pre-specified data saturation was not used to decide when to stop the semi-structured interviews. It is also important to note that the findings presented here on COVID-19 did not stand in isolation from other factors influencing participation such as altruism, trust, impact of study benefits and perceptions of risk, which are beyond the scope of this paper. Whilst these data provide insights as to the impact of the COVID-19 pandemic on the decision of individuals who volunteered for and were enrolled in a vaccine trial, it does not capture what the impact may have been on people who decided not to volunteer, or who withdrew during the screening process. Ultimately these data represent only the views of a small fraction of the general population, the majority of whom do not participate in clinical research.\u0026nbsp;\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eWhilst the long-term impact of the pandemic on vaccine trials is as yet unknown, these data provide valuable insights as to the impact of COVID-19 on volunteers in studies of a novel plague vaccine, in both the UK and Uganda. These results suggest that there may be less of a \u0026ldquo;post-pandemic effect\u0026rdquo; in the high- than low-income setting in increasing vaccine trial participation. There was a noticeable difference in the effect of the pandemic as a motivator between studies, with both the experience of the COVID-19 pandemic and associated mass vaccination campaigns increasing Ugandan participants\u0026rsquo; knowledge about vaccines and trials and encouraging them to participate in research. \u0026nbsp;Additionally, these data are the first demonstrating the effect of the use of the ChAdOx1 nCoV-19 vaccine in mass vaccination campaigns, and healthy volunteers\u0026rsquo; perception of receiving a related investigational vaccine\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eCOVID-19 \u0026nbsp;- Coronavirus infectious disease 2019\u003c/p\u003e\n\u003cp\u003eWHO \u0026ndash; World Health Organisation\u003c/p\u003e\n\u003cp\u003eUK \u0026ndash; United Kingdom\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eEthics approval and consent to participate\u003c/h2\u003e\n\u003cp\u003eThis study was performed in line with the principles of the Declaration of Helsinki. Ethical approval for PlaVac was granted by South-Central Berkshire B Research Ethics Committee (REC) (ref:20/SC/0405). For PlaVac Uganda, approval was granted by the Oxford Tropical Research Ethics Committee (OxTREC Ref:19-22), the Uganda Virus Research Institute Research and Ethics Committee (ref:RGER220504), the Uganda National Council for Science and Technology (ref: HS2387ES); and the London School of Hygiene and Tropical Medicine (ref:28228). All participants provided written informed consent.\u003c/p\u003e\n\u003ch2\u003eConsent for publication\u003c/h2\u003e\n\u003cp\u003eAll participants gave permission for direct quotations to be used.\u003c/p\u003e\n\u003ch2\u003eAvailability of data and materials\u003c/h2\u003e\n\u003cp\u003eThe datasets used and analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003ch2\u003eCompeting interests\u003c/h2\u003e\n\u003cp\u003eAJP is chair of the UK Department of Health and Social Care’s Joint Committee on Vaccination and Immunisation but did not participate in COVID19 vaccine policy during the pandemic. AJP, AS and CR are\u0026nbsp;contributors to intellectual property licensed by Oxford University Innovation to AstraZeneca. The University of Oxford received funding from AstraZeneca to support the development of the Oxford-AstraZeneca COVID19 vaccine though the majority of the clinical development was funded by the UK Governmentr (NIHR), The Bill \u0026amp; Melinda Gates Foundation in South Africa and the Lehmann Foundation in Brazil. CSR has performed paid consultancy for Guidepoint.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThe PlaVac trials were supported by Innovate UK, part of UK Research and Innovation (PlaVac [UK] grant number: 971510, PlaVac Uganda grant number: 10026240). The views expressed in this publication are those of the authors and not necessarily those of Innovate UK or DOH. The research in Uganda was conducted at the MRC/UVRI and LSHTM Uganda Research Unit which is jointly funded by the UK Medical Research Council (MRC) part of UK Research and Innovation (UKRI), and the UK Foreign, Commonwealth and Development Office (FCDO) under the MRC/FCDO Concordat agreement. It is also part of the EDCTP2 programme supported by the European Union. This report is work commissioned by Innovate UK and DOH.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003eAuthors' contributions\u003c/h2\u003e\n\u003cp\u003eAS designed the mixed-methods \u0026nbsp;aspect of the PlaVac trials with assistance from SV and NK. AS, RM, MH, POR, MTN, and SK were engaged in the preparation and conduct of the mixed methods study. AS and RM conducted the analysis. RM, AS, and SK led the writing of the paper. AJP, SV and NK supervised the overall study. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003ch2\u003eAcknowledgements\u003c/h2\u003e\n\u003cp\u003eWe thank the participants who participated in the mixed methods study and the research team in Uganda and the UK where the study was conducted.\u003c/p\u003e\n\u003cp\u003eCSR is supported by the Equal Opportunities Foundation (Hong Kong), the Braithwaite Family Foundation.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eArshad Ali S, Baloch M, Ahmed N, et al. The outbreak of Coronavirus Disease 2019 (COVID-19)-An emerging global health threat. \u003cem\u003eJ Infect Public Health\u003c/em\u003e 2020; 13: 644-646. 2020/03/23. DOI: 10.1016/j.jiph.2020.02.033.\u003c/li\u003e\n\u003cli\u003eGarfin DR, Silver RC and Holman EA. The novel coronavirus (COVID-2019) outbreak: Amplification of public health consequences by media exposure. \u003cem\u003eHealth Psychol\u003c/em\u003e 2020; 39: 355-357. 2020/03/24. 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WEEKLY BULLETIN ON OUTBREAKS AND OTHER EMERGENCIES, Week 9: 21 \u0026ndash; 27 February 2022 2022.\u003c/li\u003e\n\u003cli\u003eBBC News. AstraZeneca: Thailand delays vaccine rollout over blood clot fears, https://www.bbc.co.uk/news/world-asia-56369550 (2021).\u003c/li\u003e\n\u003cli\u003eDanish Health Authority. Denmark continues its vaccine rollout without the COVID-19 vaccine from AstraZeneca, https://www.sst.dk/en/English/Corona-eng/Vaccination%20against%20COVID-19/AstraZeneca%20vaccine%20paused (2021, accessed 02/06/2021).\u003c/li\u003e\n\u003cli\u003eDepartment of Health and Social Care. Use of the AstraZeneca COVID-19 (AZD1222) vaccine: updated JCVI statement, 7 May 2021, https://www.gov.uk/government/publications/use-of-the-astrazeneca-covid-19-vaccine-jcvi-statement-7-may-2021/use-of-the-astrazeneca-covid-19-azd1222-vaccine-updated-jcvi-statement-7-may-2021 (2021, accessed 03/06/2021).\u003c/li\u003e\n\u003cli\u003eEuropean Medicines Agency. 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Los Angeles: SAGE, 2017.\u003c/li\u003e\n\u003cli\u003eGale NK, Heath G, Cameron E, et al. Using the framework method for the analysis of qualitative data in multi-disciplinary health research. \u003cem\u003eBMC Medical Research Methodology\u003c/em\u003e 2013; 13: 117. DOI: 10.1186/1471-2288-13-117.\u003c/li\u003e\n\u003cli\u003eMadinah N. The COVID-19 pandemic: Economic effects and government measures in Uganda. \u003cem\u003eSARJANA\u003c/em\u003e 2020; 35: 10-22.\u003c/li\u003e\n\u003cli\u003eKabajulizi J and Boysen O. The macroeconomic implications of COVID-19 pandemic and associated policies: An economy-wide analysis of Uganda. 2021.\u003c/li\u003e\n\u003cli\u003eMusoke D, Nalinya S, Lubega GB, et al. The effects of COVID-19 lockdown measures on health and healthcare services in Uganda. \u003cem\u003ePLOS global public health\u003c/em\u003e 2023; 3: e0001494.\u003c/li\u003e\n\u003cli\u003eMeskell P, Biesty LM, Dowling M, et al. Factors that impact on recruitment to vaccine trials in the context of a pandemic or epidemic: a qualitative evidence synthesis. \u003cem\u003eCochrane Database Syst Rev\u003c/em\u003e 2023; 9: Mr000065. 2023/09/01. DOI: 10.1002/14651858.MR000065.pub2.\u003c/li\u003e\n\u003cli\u003eHelary A, Botelho-Nevers E, Bonneton M, et al. Factors, motivations and barriers associated with eagerness to volunteer in COVID-19 vaccine clinical trials in France: A mixed-method study. \u003cem\u003eVaccine\u003c/em\u003e 2024 2024/06/24. DOI: 10.1016/j.vaccine.2024.06.003.\u003c/li\u003e\n\u003cli\u003eKabagenyi A, Wasswa R, Nannyonga BK, et al. Factors Associated with COVID-19 Vaccine Hesitancy in Uganda: A Population-Based Cross-Sectional Survey. \u003cem\u003eInt J Gen Med\u003c/em\u003e 2022; 15: 6837-6847. 2022/09/06. DOI: 10.2147/ijgm.S372386.\u003c/li\u003e\n\u003cli\u003eRandall DM, Paul Huo Y and Pawelk P. SOCIAL DESIRABILITY BIAS IN CROSS‐CULTURAL ETHICS RESEARCH. \u003cem\u003eThe International Journal of Organizational Analysis\u003c/em\u003e 1993; 1: 185-202. DOI: 10.1108/eb028788.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-public-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pubh","sideBox":"Learn more about [BMC Public Health](http://bmcpublichealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pubh/default.aspx","title":"BMC Public Health","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Plague, vaccine, motivations, COVID-19, healthy volunteers","lastPublishedDoi":"10.21203/rs.3.rs-6657828/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6657828/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBackground\u003c/p\u003e\n\u003cp\u003eThe COVID-19 pandemic led to unprecedented interest and participation in vaccine trials globally, and a concurrent increase in vaccine hesitancy. Whether this impacted recruitment of healthy volunteers to subsequent non-COVID vaccine trials is not well studied. We explored the impact of the COVID-19 pandemic on motivations for participating in two clinical trials of the same novel anti-plague vaccine, conducted in the United Kingdom (UK) and Uganda in 2021 and 2022.\u003c/p\u003e\n\u003cp\u003eMethods\u003c/p\u003e\n\u003cp\u003eParticipants enrolled in PlaVac (UK) and PlaVac Uganda, Phase I trials of ChAdOx1 Plague vaccine, were invited to complete an optional questionnaire and semi-structured interview examining motivations for participating, including questions on the impact of the COVID-19 pandemic on their decision. Questionnaires were self-administered and interviewer-administered for UK and Uganda studies, respectively. Interviews were conducted in local languages, transcribed in English, and analysed using thematic analysis. Results were compared between studies.\u003c/p\u003e\n\u003cp\u003eResults\u003c/p\u003e\n\u003cp\u003eThirty-one of the 45 (25.8% female) UK trial participants and all 36 (27.8% female) of the Uganda trial participants completed questionnaires. Nine UK questionnaire respondents, and 19 Uganda questionnaire respondents completed interviews. Responses to questions on the impact of the COVID-19 pandemic on volunteering decisions were divergent between countries, with little effect for UK participants but a strong positive effect for Ugandan participants. Themes relating to this effect in Uganda were \u003cem\u003epreparedness\u003c/em\u003e (wanting to contribute to vaccine development to prevent suffering and death from future epidemics), \u003cem\u003eincreased awareness\u003c/em\u003e(understanding the vaccine development process and seeing rapidly deployed COVID-19 vaccine trials gave them confidence), and \u003cem\u003epersonal protection\u003c/em\u003e(believing themselves to be protected by the novel plague vaccine). \u0026nbsp;Participants in both studies expressed trust and confidence in the study plague vaccine which shares the ChAdOx1 platform with the ChAdOx1 nCoV-19 (Vaxzevria, AstraZeneca) vaccine.\u003c/p\u003e\n\u003cp\u003eConclusions\u003c/p\u003e\n\u003cp\u003eFor Ugandan participants, COVID-19 and mass vaccination increased knowledge about vaccines and trials and encouraged them to participate in research, but had little impact on UK volunteers. There was no evidence of a negative effect of perceptions of the related ChAdOx1 nCoV-19 vaccine on trial participants' confidence in the novel plague vaccine's safety.\u003c/p\u003e\n\u003cp\u003eTrial registrations\u003c/p\u003e\n\u003cp\u003eCurrent controlled trial: ISRCTN41077863, prospective registration date: 19/03/2021, and current controlled trial: ISRCTN79243381, prospective registration date 05/08/2022.\u003c/p\u003e","manuscriptTitle":"The impact of the COVID-19 pandemic on healthy volunteer motivations: a mixed-methods study of participants in plague vaccine trials in the UK and Uganda","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-17 09:07:19","doi":"10.21203/rs.3.rs-6657828/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-05T13:38:15+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-03T14:40:34+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-24T20:22:39+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-18T14:33:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"200921520110416475777593873633947339785","date":"2025-12-18T09:14:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"46230535138149748617201059304245214610","date":"2025-12-17T13:31:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"53816119016963803814082542429093342202","date":"2025-12-17T11:08:50+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-23T13:11:15+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-04T07:58:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"158152849305690468343271652068504862039","date":"2025-06-26T12:58:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"138988123437639677254405287934623068203","date":"2025-06-19T04:30:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"316157787449114910771639130435236793822","date":"2025-06-13T07:09:54+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-06-12T05:04:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-06-10T05:51:40+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-05-19T06:19:04+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-16T12:30:51+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Public Health","date":"2025-05-16T12:29:41+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-public-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pubh","sideBox":"Learn more about [BMC Public Health](http://bmcpublichealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pubh/default.aspx","title":"BMC Public Health","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3d38eb18-61a3-4edf-b089-66b3a5aa010d","owner":[],"postedDate":"June 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-01T13:56:51+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-17 09:07:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6657828","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6657828","identity":"rs-6657828","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}