Substantial delays in care-seeking for post-vaccination abscesses: a threat to infant health and immunization trust in Timor-Leste

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While systemic barriers to healthcare are widely documented, quantitative evidence on how these barriers directly impact care-seeking for AEFIs—and consequently threaten immunisation program credibility—remains limited. This study examined care-seeking delays for abscesses following Hepatitis B birth dose (HepB-BD) administration in Timor-Leste as a case study of this global challenge. Methods This descriptive cross-sectional study was conducted using the 2024 AEFI surveillance line list of Timor-Leste. All reported cases of abscesses in infants (0–12 months old) following HepB-BD were included in this study. The primary outcome was care-seeking delay, defined as the number of days between the caregiver's notice of the abscess and the first formal healthcare consultation. Data were analysed using descriptive statistical methods. Results Among 41 reported cases, the median care-seeking delay was 17 days (range: 1–44 days). Only 36.6% of caregivers sought care within 10 days, whereas 43.9% delayed care-seeking beyond 20 days. Less than half of the infants (46.3%) received HepB-BD within 24 hours of birth. Conclusion The prolonged delays observed underscore a critical failure point in the immunisation continuum within fragile health systems, where logistical and financial barriers overwhelm caregivers’ decision-making. This study provides quantitative evidence that AEFI management is not merely a clinical concern but a pivotal trust-building interface between communities and health systems. Interventions must integrate active community education, healthcare worker training in AEFI communication, and tangible support to overcome systemic access barriers, a strategy relevant for similar low-resource settings globally. Adverse events following immunisation Healthcare-seeking behaviour Hepatitis B vaccine Abscess Timor-Leste Figures Figure 1 Figure 2 1. Introduction Hepatitis B virus (HBV) infection represents a significant global health issue. As reported in the "Global progress report on HIV, viral hepatitis, and sexually transmitted infections, 2021" by the World Health Organization (WHO), the prevalence of hepatitis B surface antigen (HBsAg) in the general population was 3.8% in 2019. Moreover, approximately 1.5 million new infections and 296 million individuals have chronic HBV infection. Furthermore, HBV infection has resulted in 820,000 deaths due to liver failure, cirrhosis, and hepatocellular carcinoma (HCC) [ 1 ]. Vaccination against hepatitis B has been shown to confer over 95% protection from infection. According to estimates by the WHO, prior to the widespread implementation of vaccination in 2000, approximately 5% of children under the age of five were infected with the hepatitis B virus (HBV). By 2019, this proportion had declined to less than 1% [ 2 ]. WHO describes Adverse Events Following Immunization (AEFI) as any negative medical incident that occurs after vaccination, which may not necessarily be linked to the vaccine itself. These adverse events can encompass any undesirable or unexpected signs, unusual laboratory results, symptoms, or illnesses (1) and are categorized into five distinct types: vaccine product–related reactions, vaccine quality defect–related reactions, immunization error–related reactions, immunization anxiety–associated reactions, and coincidental events [ 3 ]. Globally, the reported incidence of AEFIs varies by country. According to WHO estimates, the occurrence of serious AEFIs is approximately 1 per 100,000 doses administered, whereas non-serious AEFIs are more prevalent and frequently underreported [ 4 ]. Injection-site reactions, such as swelling, redness, and abscesses, are among the most commonly reported non-serious events, particularly in low-resource settings where cold chain and aseptic techniques may be compromised. Abscess formation following immunisation, particularly AEFIs such as subcutaneous abscesses, is frequently linked to immunisation errors and improper administration. These occurrences have been documented with vaccines such as Bacillus Calmette-Guérin (BCG) and hepatitis B, which predominantly affect young children. Such AEFI incidents can erode trust in vaccination programs, prompting individuals to seek care from traditional medicine practitioners or delay visits to formal healthcare facilities [ 5 , 6 ]. In Timor-Leste, the government provides free public healthcare services, including vaccinations for children. However, numerous barriers hindered equitable access to these services. A significant study conducted in 2016 underscored this issue, citing a community member who expressed, “I go I die, I stay I die, better to stay and die in my house.” This statement reflects the profound frustration experienced by individuals due to these access challenges.[ 6 ]. The research identified onerous physical, financial, and sociocultural barriers—such as lack of patient transport, prohibitive out-of-pocket costs for families, and experiences of staff denigration—that deter hospital care-seeking. Moreover, a different study found that traditional medicine is often considered an affordable, accessible, and acceptable substitute for formal healthcare [ 7 ]. A three-dose infant hepatitis B vaccination series was implemented in Timor-Leste in 2007, with the introduction of a hepatitis B birth dose in 2016 [ 8 ]. According to the WHO/UNICEF joint estimates of national immunization coverage (WUENIC), the coverage of hepatitis B birth doses was 76% from 2021 to 2024 [ 9 ]. In numerous low- and middle-income countries (LMICs), health systems face structural weaknesses that manifest as barriers to access [ 6 , 10 , 11 ]. Consequently, responses to AEFIs, such as abscesses, are often suboptimal. A previous study in a limited setting found that parental concern of parents sought medical attention due to an AEFI 6.9% of parents who reported no AEFI[ 12 ]. Timor-Leste [ 6 ], with its documented challenges in transportation, costs, and perceived quality of care, serves as a pertinent case study of a fragile health system. Within such contexts, responses to AEFIs are often suboptimal, yet quantitative data delineating the specific patterns and determinants of care-seeking behaviors remain critically deficient. By systematically analyzing caregiver responses to abscesses following HepB-BD, this study aims to quantify healthcare-seeking delays [ 1 , 5 , 6 , 8 ]and frame them as symptomatic of systemic access failures. These findings are intended to generate evidence-based, transferable insights for strengthening AEFI management, safeguarding infant health, and protecting the credibility of immunization programs not only in Timor-Leste but in comparable settings worldwide.". 2. Methods 2.1 Study design and setting We performed a descriptive cross-sectional analysis using the existing national surveillance data. 2.2 Data Source The analysis employed secondary data from Timor-Leste's National Adverse Event Following Immunization (AEFI) Line List for 2024. This line list serves as the passive AEFI surveillance register for the country and is systematically compiled from reports submitted by health facility staff. 2.3 Study Population and Case Selection This retrospective analysis used all data from the national 2024 Adverse Event Following Immunization (AEFI) line list. The initial dataset contained 58 reported AEFI cases during the surveillance period. Cases were selected for inclusion in this analysis based on the following criteria. Vaccine: The reported adverse event following immunization (AEFI) must have occurred after the administration of the Hepatitis B birth dose (HepB-BD). Adverse Events: The reported outcome must be a suspected injection-site abscess. Data Completeness: The case record must contain comprehensive data for the core study variables, including infant age, vaccination details, and dates related to abscess onset and healthcare presentation. The selection process is illustrated in the flowchart (Fig. 1 ). A total of 58 reports were evaluated for their eligibility. Seventeen cases were excluded: 15 unrelated to HepB-BD vaccination and 2 due to incomplete core data. Consequently, the final analytical sample comprised 41 confirmed cases of post-HepB-BD abscesses in infants aged 0–12 months with complete information. 2.4 Variables and Data Extraction Using existing records, we extracted and analyzed the following variables for each identified case: Infant characteristics Vaccination details Abscess episode Sex Health facility where the HepB-BD was administered, Date of AEFI report Age Date of administration, and Date of symptom onset (abscess noticed), Municipality of residence timeliness (based on date of birth Date of first healthcare presentation for the abscess. 2.5 Data analysis Data were analyzed using descriptive statistics in SPSS (version 26). Categorical variables are presented as frequencies and percentages. Continuous variables were summarized using the median and range. The primary outcome, delay in care-seeking, was calculated as the number of days between the caregiver-reported date of abscess notice and the date of the first formal healthcare presentation. 2.5 Ethics This analysis utilized an anonymized secondary dataset from the national 2024 Adverse Events Following Immunization (AEFI) line list, a routine public health surveillance activity. The use of this de-identified data for epidemiological research aligns with the World Health Organization (WHO) guidelines for ethical issues in public health surveillance and the Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER). The study protocol, as a non-interventional analysis of anonymized data, was exempt from formal ethics committee review. 3. Results 3.1 Infant and Vaccination Characteristics Most infants were female (56.1%, n = 23/41), and the median age at abscess onset was 15 days (range: 2–53 days). The median time from birth to HepB-BD administration was 2 days (range, 0–28 days). Less than half of the infants (46.3%, n = 19/41) received the vaccine within the recommended 24 h after birth. The majority (65.9%, n = 27/41) received their HepB-BD at a community health centre (Table 1 ) Table 1 Characteristics of infants with reported injection‑site abscess after hepatitis B birth‑dose vaccination, Timor‑Leste, 2024 (n = 18) Characteristic n % Age (weekly Intervals) Median, Min-Max 15 (2–53) days Week 1 (1–7 days) 7 17.1 Week 2 (8–14 days) 10 24.4 Week 3 (15–21 days) 12 29.3 Week 4+ (22–53 days) 12 29.3 Sex Female 23 56.1 Male 18 43.9 HepB-BD Timeliness Median, Min-Max 2 (0–28) days Administered within 24 hours 19 46.3 Administered after 24 hours 22 53.7 Health Facility Received Hepatitis B dose Health Post 7 17.1 Community Health Center 27 65.9 Referral Hospital 7 17.1 3.2 Health-care-seeking delays following abscess recognition Data on the delay between caregiver recognition of a suspected injection-site abscess and seeking formal healthcare were available for 41 patients. The median delay in seeking formal care was 17 days (range: 1–44 days; standard deviation: 12.24 days), indicating that half of the caregivers delayed seeking formal care for over two weeks after the initial observation of the condition. As illustrated in Fig. 1 , the distribution of these delays shows that just over one-third of the caregivers (15/41, 36.6%) sought healthcare within 10 days. The most frequently observed delay interval was greater than 20 days (18/41, 43.9%). A significant proportion of patients (8/41, 19.5%) experienced delays of 11–20 days, with the longest delay being 44 days. 4. Discussion This descriptive study, using national AEFI surveillance data, quantifies a critical gap in the immunization safety net within a fragile health system. The median 17-day delay in seeking care for post-vaccination abscesses, with 43.9% of caregivers waiting over 20 days, represents more than a behavioral pattern—it is a direct indicator of system failure. This delay, occurring alongside suboptimal HepB-BD timeliness (46.3% within 24 hours), highlights linked vulnerabilities across the immunization cascade, from service delivery to complication management. For similar LMICs, these co-occurring delays signal where program strengthening should be prioritized. The observed delays must be interpreted within the specific, multilayered context of healthcare access in Timor-Leste. Price et al. (2016) conducted a pivotal study that highlighted the persistent "onerous physical, financial, and socio-cultural barriers" that remain in place, even though services are ostensibly offered for free [ 6 ]. The identified "critical cross-cutting issue" of lack of patient transport is directly relevant to our findings. For caregivers of infants developing an abscess, the logistical and financial burden of travelling to a health facility can be a prohibitive first barrier, prompting a "wait-and-see" approach. Furthermore, documented experiences of out-of-pocket ancillary costs, nepotism, and perceived poor treatment by staff create a powerful disincentive to engage with the formal system [ 6 ]. In this environment, traditional medicine often serves as an accessible, affordable, and culturally acceptable first-line response, potentially explaining the extreme delays recorded before formal healthcare was sought. These local systemic barriers interact with the global evidence on AEFI management. International studies suggest that experiences with AEFIs can erode vaccine confidence, and that parents who seek care for AEFIs often hold more cautious attitudes toward immunization [ 12 , 13 ]. The Timor-Leste case illustrates a broader paradigm relevant to fragile health systems globally: when an AEFI occurs, it activates not just medical concern but also a calculus of access. The caregiver’s decision to delay formal care is often a rational response to anticipated logistical hardship, financial burden, and potential disrespect. Therefore, the prolonged delays documented here pose a multidimensional threat: to infant health through increased risk of severe infection, and to the immunization program through erosion of community trust. This risk is amplified in contexts where vaccine coverage is already suboptimal. Addressing this issue requires moving beyond AEFI reporting to actively managing the community experience of AEFIs—a lesson with direct applicability for other LMICs striving to maintain immunization confidence amidst systemic constraints.. Frontline healthcare workers (HCWs) play a pivotal role in this dynamic. Studies from similar low-resource settings, such as Uganda, indicate a common gap where HCWs may have theoretical knowledge of AEFIs but lack practical familiarity with reporting systems and, crucially, effective patient communication protocols [ 14 ]. This knowledge-to-practice gap likely exists in Timor-Leste and has direct consequences. Without proficient skills in AEFI recognition, empathetic counseling, and clear guidance on when and where to seek care, HCWs are ill-equipped to mitigate the barriers described by the caregivers. Inadequate pre-vaccination counseling about common side effects, such as local reactions, leaves families unprepared, increasing alarm and potentially driving them towards informal care when such reactions occur. Our study had several limitations. Although the sample size captured all reported serious abscess cases in 2024, it was small and limited the detailed subgroup analysis. Reliance on caregiver recall for dates introduces the potential for recall bias. Most significantly, our reliance on the national passive AEFI surveillance system means that we inherently miss cases where caregivers never sought formal care—precisely the population most affected by access barriers and likely to experience the longest delays. This selection bias suggests our findings, concerning as they are, may underestimate the true magnitude of delayed care-seeking and disengagement from the formal health system. Conclusion and Recommendations In conclusion, this analysis quantifies a severe care-seeking delay for AEFIs within a fragile health system, using Timor-Leste as an illustrative case. The delay is a symptom of systemic barriers that deter timely help-seeking. To address this, a multi-pronged strategy is required, the principles of which are generalizable to comparable settings: Integrate AEFI management with access solutions: Community education must be coupled with practical support (e.g., transport mechanisms, community health worker follow-up) to overcome the primary logistical barriers that drive delays. Reframe healthcare worker training: Capacity building must extend beyond AEFI identification to include competency in empathetic communication, counseling, and trust-building to mitigate negative perceptions and guide appropriate care-seeking. Complement passive surveillance with active safety-nets: Systems should incorporate active follow-up for serious AEFIs to identify disengaged families, turning surveillance into a protective intervention. Embed AEFI responses within broader health systems strengthening: Sustained improvement requires addressing foundational barriers—transport, financial protection, and quality of care—as part of universal health coverage agendas. By demonstrating how systemic failures translate into dangerous care-seeking delays, this study underscores that robust AEFI management is a cornerstone of both infant safety and immunization program resilience in fragile health systems worldwide. Declarations Human Ethics and Consent to Participate declarations: not applicable. Funding: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Author Contribution Name Contribution(s)Filipe de Neri Machado Conceptualization, Methodology, SupervisionNoel Soares Gama Validation, Writing – Original Draft PreparationNazario Barreto dos Santos Conceptualization, Data Curation, Project AdministrationBenigna Veneranda da Costa Amaral Formal Analysis, Writing – Original Draft PreparationJimmi Bruno de Oliveira Software, Formal Analysis, VisualizationVenesia Tirana Guterres Methodology, Data Curation, Project AdministrationAloto Ximenes Belo Amaral Software, Writing – Review & EditingDioneia Benevides Monteiro Validation, Writing – Review & EditingMariano da Silva Marques Conceptualization, Methodology, SupervisionAll authors reviewed the manuscript References Organization WH. Global progress report on HIV, viral hepatitis and sexually transmitted infections, 2021: accountability for the global health sector strategies 2016–2021: actions for impact. World Health Organization; 2021. World Health O. Hepatitis B vaccines: WHO position paper, July 2017 – Recommendations. Vaccine. 2019;37(2):223–5. Organization WH. Causality assessment of an adverse event following immunization (AEFI): user manual for the revised WHO classification. 2018. Chen RT et al. The vaccine adverse event reporting system (VAERS). 1994. 12(6): pp. 542–50. Bisetto LH, Ciosak SI. Analysis of adverse events following immunization caused by immunization errors. Rev Bras Enferm. 2017;70(1):87–95. Price JA, et al. I go I die, I stay I die, better to stay and die in my house: understanding the barriers to accessing health care in Timor-Leste. BMC Health Serv Res. 2016;16(1):535. Grace R, Vaz J, Costa JD. Traditional medicine use in Timor-Leste. BMC Complement Med Ther. 2020;20(1):165. Arkell P, et al. A population-representative serosurvey estimating vaccine-induced immunity against measles, rubella, hepatitis B and severe acute respiratory syndrome coronavirus 2 in Timor-Leste. The Lancet Regional Health - Southeast Asia; 2025. p. 34. World Health O. Hepatitis B Vaccination Coverage for Timor-Leste . WHO Immunization Data portal 2026/01/09/ Accessed: 9 January 2026; Available from: https://immunizationdata.who.int/global/wiise-detail-page/hepatitis-b-vaccination-coverage?CODE=TLS&ANTIGEN=HEPB_BD&YEAR =. Zwi A et al. Timor-Leste Health Care Seeking Behaviour Study, Final Report . 2009. Ketema DB, et al. Individual- and community-level predictors of healthcare-seeking behaviour for acute respiratory tract infections among children under five in 29 low- and middle-income countries: a multilevel analysis. Public Health. 2024;237:71–6. Gust DA, et al. Parental Concerns and Medical-Seeking Behavior After Immunization. Am J Prev Med. 2006;31(1):32–5. Parrella A, et al. Parental perspectives of vaccine safety and experience of adverse events following immunisation. Vaccine. 2013;31(16):2067–74. Watyaba B, et al. Knowledge and reporting of adverse events following childhood immunization (AEFI) among health workers and caregivers at Mengo Hospital (2021), Kampala, Uganda: A mixed-methods study. PLOS Global Public Health. 2025;5(7):e0004827. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 14 Mar, 2026 Reviewers agreed at journal 06 Mar, 2026 Reviews received at journal 05 Mar, 2026 Reviewers agreed at journal 26 Feb, 2026 Reviewers invited by journal 25 Feb, 2026 Editor invited by journal 05 Feb, 2026 Editor assigned by journal 03 Feb, 2026 Submission checks completed at journal 03 Feb, 2026 First submitted to journal 26 Jan, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8704552","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":597893485,"identity":"b6b52998-b389-48bd-9c5b-0129f80b516a","order_by":0,"name":"Filipe de Neri Machado","email":"","orcid":"","institution":"Instituto Nacional de Saúde Pública, Timor Leste","correspondingAuthor":false,"prefix":"","firstName":"Filipe","middleName":"de Neri","lastName":"Machado","suffix":""},{"id":597893486,"identity":"65ae3fa2-f3ae-4fab-b101-cbcaf065c512","order_by":1,"name":"Noel Soares Gama","email":"","orcid":"","institution":"Instituto Nacional de Saúde Pública, Timor Leste","correspondingAuthor":false,"prefix":"","firstName":"Noel","middleName":"Soares","lastName":"Gama","suffix":""},{"id":597893487,"identity":"b7b4ed2f-d72f-46ec-9b5e-105486291624","order_by":2,"name":"Nazario Barreto dos Santos","email":"","orcid":"","institution":"Instituto Nacional de Saúde Pública, Timor Leste","correspondingAuthor":false,"prefix":"","firstName":"Nazario","middleName":"Barreto dos","lastName":"Santos","suffix":""},{"id":597893488,"identity":"e2fc5f89-d42a-4954-ba30-16bd8e73a162","order_by":3,"name":"Benigna Veneranda da Costa Amaral","email":"","orcid":"","institution":"Instituto Nacional de Saúde Pública, Timor Leste","correspondingAuthor":false,"prefix":"","firstName":"Benigna","middleName":"Veneranda da Costa","lastName":"Amaral","suffix":""},{"id":597893489,"identity":"2f164ec0-cc17-4230-84a9-a6f90dd7a0a3","order_by":4,"name":"Jimmi Bruno de Oliveira","email":"","orcid":"","institution":"Instituto Nacional de Saúde Pública, Timor Leste","correspondingAuthor":false,"prefix":"","firstName":"Jimmi","middleName":"Bruno","lastName":"de Oliveira","suffix":""},{"id":597893490,"identity":"f55c5d69-179a-415a-9abb-a13a53075215","order_by":5,"name":"Venesia Tirana Guterres","email":"","orcid":"","institution":"Hospital Nacional Guido Valadares","correspondingAuthor":false,"prefix":"","firstName":"Venesia","middleName":"Tirana","lastName":"Guterres","suffix":""},{"id":597893491,"identity":"e674c737-7803-4b7b-ac99-c319c0b4c079","order_by":6,"name":"Aloto Ximenes Belo Amaral","email":"","orcid":"","institution":"Instituto Nacional de Saúde Pública, Timor Leste","correspondingAuthor":false,"prefix":"","firstName":"Aloto","middleName":"Ximenes Belo","lastName":"Amaral","suffix":""},{"id":597893492,"identity":"8c67b346-0e68-4677-a5ac-8814768e235e","order_by":7,"name":"Dioneia Benevides Monteiro","email":"","orcid":"","institution":"Hospital Nacional Guido Valadares","correspondingAuthor":false,"prefix":"","firstName":"Dioneia","middleName":"Benevides","lastName":"Monteiro","suffix":""},{"id":597893493,"identity":"cc917622-2fe9-4b9e-ac69-ca16c7271711","order_by":8,"name":"Mariano da Silva Marques","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9ElEQVRIiWNgGAWjYDCCAwgm84OEChDF3EC0FjaDB2dAWhiJ18Ig+bANRBHQwnf7AOuGn3usE/v5jz8wSJxXG83fDtTyo2IbTi2S5xLYbvY8S0+cOSPH4EHituO5Mw4zNjD2nLmNU4vBGQa2GzwHDiduuMHDYJC47VhuA1ALM2Mbfi03/wC17D9//IFE4pxjufOJ0XIbbAtDgoFEYkNN7gZCWiTPAGVlDqQbz7iRY2aQcOxA7kagloP4/MJ3hvnYzTcHrGX7+48/fvijpi533vnDBx/8qMCtBRoLzDDeYTB5AI96GIBrqSNC8SgYBaNgFIw0AADau2W5Hs5icgAAAABJRU5ErkJggg==","orcid":"","institution":"Instituto Nacional de Saúde Pública, Timor Leste","correspondingAuthor":true,"prefix":"","firstName":"Mariano","middleName":"da Silva","lastName":"Marques","suffix":""}],"badges":[],"createdAt":"2026-01-27 01:23:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8704552/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8704552/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104168390,"identity":"6b3f4088-f834-4d08-a9c5-510ea56add5a","added_by":"auto","created_at":"2026-03-08 14:30:44","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":68004,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFlowchart of case selection from the 2024 AEFI line list\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8704552/v1/2866f49f7bc808824e973add.png"},{"id":104168388,"identity":"19bec8e8-980a-437d-a4d9-35db9fcd81ed","added_by":"auto","created_at":"2026-03-08 14:30:44","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":11000,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 1. Delay in seeking formal healthcare after the caregiver noticed a suspected injection-site abscess (n=41) \u003cem\u003e(min=1, max=44, median=17, SD=12.24).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8704552/v1/74c2c630aef60f3016cf974a.png"},{"id":104168392,"identity":"01d529b1-69cb-4b4d-b296-66d1277041db","added_by":"auto","created_at":"2026-03-08 14:30:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":695485,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8704552/v1/f001a14c-d85d-4db1-8b38-360dff0def55.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Substantial delays in care-seeking for post-vaccination abscesses: a threat to infant health and immunization trust in Timor-Leste","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eHepatitis B virus (HBV) infection represents a significant global health issue. As reported in the \"Global progress report on HIV, viral hepatitis, and sexually transmitted infections, 2021\" by the World Health Organization (WHO), the prevalence of hepatitis B surface antigen (HBsAg) in the general population was 3.8% in 2019. Moreover, approximately 1.5\u0026nbsp;million new infections and 296\u0026nbsp;million individuals have chronic HBV infection. Furthermore, HBV infection has resulted in 820,000 deaths due to liver failure, cirrhosis, and hepatocellular carcinoma (HCC) [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Vaccination against hepatitis B has been shown to confer over 95% protection from infection. According to estimates by the WHO, prior to the widespread implementation of vaccination in 2000, approximately 5% of children under the age of five were infected with the hepatitis B virus (HBV). By 2019, this proportion had declined to less than 1% [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWHO describes Adverse Events Following Immunization (AEFI) as any negative medical incident that occurs after vaccination, which may not necessarily be linked to the vaccine itself. These adverse events can encompass any undesirable or unexpected signs, unusual laboratory results, symptoms, or illnesses (1) and are categorized into five distinct types: vaccine product\u0026ndash;related reactions, vaccine quality defect\u0026ndash;related reactions, immunization error\u0026ndash;related reactions, immunization anxiety\u0026ndash;associated reactions, and coincidental events [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eGlobally, the reported incidence of AEFIs varies by country. According to WHO estimates, the occurrence of serious AEFIs is approximately 1 per 100,000 doses administered, whereas non-serious AEFIs are more prevalent and frequently underreported [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Injection-site reactions, such as swelling, redness, and abscesses, are among the most commonly reported non-serious events, particularly in low-resource settings where cold chain and aseptic techniques may be compromised.\u003c/p\u003e \u003cp\u003eAbscess formation following immunisation, particularly AEFIs such as subcutaneous abscesses, is frequently linked to immunisation errors and improper administration. These occurrences have been documented with vaccines such as Bacillus Calmette-Gu\u0026eacute;rin (BCG) and hepatitis B, which predominantly affect young children. Such AEFI incidents can erode trust in vaccination programs, prompting individuals to seek care from traditional medicine practitioners or delay visits to formal healthcare facilities [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn Timor-Leste, the government provides free public healthcare services, including vaccinations for children. However, numerous barriers hindered equitable access to these services. A significant study conducted in 2016 underscored this issue, citing a community member who expressed, \u0026ldquo;I go I die, I stay I die, better to stay and die in my house.\u0026rdquo; This statement reflects the profound frustration experienced by individuals due to these access challenges.[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The research identified onerous physical, financial, and sociocultural barriers\u0026mdash;such as lack of patient transport, prohibitive out-of-pocket costs for families, and experiences of staff denigration\u0026mdash;that deter hospital care-seeking. Moreover, a different study found that traditional medicine is often considered an affordable, accessible, and acceptable substitute for formal healthcare [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. A three-dose infant hepatitis B vaccination series was implemented in Timor-Leste in 2007, with the introduction of a hepatitis B birth dose in 2016 [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. According to the WHO/UNICEF joint estimates of national immunization coverage (WUENIC), the coverage of hepatitis B birth doses was 76% from 2021 to 2024 [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn numerous low- and middle-income countries (LMICs), health systems face structural weaknesses that manifest as barriers to access [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Consequently, responses to AEFIs, such as abscesses, are often suboptimal. A previous study in a limited setting found that parental concern of parents sought medical attention due to an AEFI 6.9% of parents who reported no AEFI[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Timor-Leste [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], with its documented challenges in transportation, costs, and perceived quality of care, serves as a pertinent case study of a fragile health system. Within such contexts, responses to AEFIs are often suboptimal, yet quantitative data delineating the specific patterns and determinants of care-seeking behaviors remain critically deficient. By systematically analyzing caregiver responses to abscesses following HepB-BD, this study aims to quantify healthcare-seeking delays [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]and frame them as symptomatic of systemic access failures. These findings are intended to generate evidence-based, transferable insights for strengthening AEFI management, safeguarding infant health, and protecting the credibility of immunization programs not only in Timor-Leste but in comparable settings worldwide.\".\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Study design and setting\u003c/h2\u003e \u003cp\u003eWe performed a descriptive cross-sectional analysis using the existing national surveillance data.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Data Source\u003c/h2\u003e \u003cp\u003eThe analysis employed secondary data from Timor-Leste's National Adverse Event Following Immunization (AEFI) Line List for 2024. This line list serves as the passive AEFI surveillance register for the country and is systematically compiled from reports submitted by health facility staff.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Study Population and Case Selection\u003c/h2\u003e \u003cp\u003eThis retrospective analysis used all data from the national 2024 Adverse Event Following Immunization (AEFI) line list. The initial dataset contained 58 reported AEFI cases during the surveillance period.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eCases were selected for inclusion in this analysis based on the following criteria.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eVaccine: The reported adverse event following immunization (AEFI) must have occurred after the administration of the Hepatitis B birth dose (HepB-BD).\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eAdverse Events: The reported outcome must be a suspected injection-site abscess.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eData Completeness: The case record must contain comprehensive data for the core study variables, including infant age, vaccination details, and dates related to abscess onset and healthcare presentation.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eThe selection process is illustrated in the flowchart (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003e). A total of 58 reports were evaluated for their eligibility. Seventeen cases were excluded: 15 unrelated to HepB-BD vaccination and 2 due to incomplete core data. Consequently, the final analytical sample comprised 41 confirmed cases of post-HepB-BD abscesses in infants aged 0\u0026ndash;12 months with complete information.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Variables and Data Extraction\u003c/h2\u003e \u003cp\u003eUsing existing records, we extracted and analyzed the following variables for each identified case:\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInfant characteristics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVaccination details\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAbscess episode\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHealth facility where the HepB-BD was administered,\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDate of AEFI report\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDate of administration, and\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDate of symptom onset (abscess noticed),\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMunicipality of residence\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003etimeliness (based on date of birth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDate of first healthcare presentation for the abscess.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Data analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using descriptive statistics in SPSS (version 26). Categorical variables are presented as frequencies and percentages. Continuous variables were summarized using the median and range. The primary outcome, delay in care-seeking, was calculated as the number of days between the caregiver-reported date of abscess notice and the date of the first formal healthcare presentation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Ethics\u003c/h2\u003e \u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThis analysis utilized an anonymized secondary dataset from the national 2024 Adverse Events Following Immunization (AEFI) line list, a routine public health surveillance activity. The use of this de-identified data for epidemiological research aligns with the World Health Organization (WHO) guidelines for ethical issues in public health surveillance and the Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER). The study protocol, as a non-interventional analysis of anonymized data, was exempt from formal ethics committee review.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Infant and Vaccination Characteristics\u003c/h2\u003e \u003cp\u003eMost infants were female (56.1%, n\u0026thinsp;=\u0026thinsp;23/41), and the median age at abscess onset was 15 days (range: 2\u0026ndash;53 days). The median time from birth to HepB-BD administration was 2 days (range, 0\u0026ndash;28 days). Less than half of the infants (46.3%, n\u0026thinsp;=\u0026thinsp;19/41) received the vaccine within the recommended 24 h after birth. The majority (65.9%, n\u0026thinsp;=\u0026thinsp;27/41) received their HepB-BD at a community health centre (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCharacteristics of infants with reported injection‑site abscess after hepatitis B birth‑dose vaccination, Timor‑Leste, 2024 (n\u0026thinsp;=\u0026thinsp;18)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e%\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (weekly Intervals)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedian, Min-Max\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15 (2\u0026ndash;53) days\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeek 1 (1\u0026ndash;7 days)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e17.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeek 2 (8\u0026ndash;14 days)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e24.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeek 3 (15\u0026ndash;21 days)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e29.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeek 4+ (22\u0026ndash;53 days)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e29.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e56.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e43.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHepB-BD Timeliness\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedian, Min-Max\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (0\u0026ndash;28) days\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdministered within 24 hours\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e46.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdministered after 24 hours\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e53.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHealth Facility Received Hepatitis B dose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHealth Post\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e17.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCommunity Health Center\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e65.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eReferral Hospital\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e17.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Health-care-seeking delays following abscess recognition\u003c/h2\u003e \u003cp\u003eData on the delay between caregiver recognition of a suspected injection-site abscess and seeking formal healthcare were available for 41 patients. The median delay in seeking formal care was 17 days (range: 1\u0026ndash;44 days; standard deviation: 12.24 days), indicating that half of the caregivers delayed seeking formal care for over two weeks after the initial observation of the condition. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the distribution of these delays shows that just over one-third of the caregivers (15/41, 36.6%) sought healthcare within 10 days. The most frequently observed delay interval was greater than 20 days (18/41, 43.9%). A significant proportion of patients (8/41, 19.5%) experienced delays of 11\u0026ndash;20 days, with the longest delay being 44 days.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThis descriptive study, using national AEFI surveillance data, quantifies a critical gap in the immunization safety net within a fragile health system. The median 17-day delay in seeking care for post-vaccination abscesses, with 43.9% of caregivers waiting over 20 days, represents more than a behavioral pattern—it is a direct indicator of system failure. This delay, occurring alongside suboptimal HepB-BD timeliness (46.3% within 24 hours), highlights linked vulnerabilities across the immunization cascade, from service delivery to complication management. For similar LMICs, these co-occurring delays signal where program strengthening should be prioritized.\u003c/p\u003e \u003cp\u003eThe observed delays must be interpreted within the specific, multilayered context of healthcare access in Timor-Leste. Price et al. (2016) conducted a pivotal study that highlighted the persistent \"onerous physical, financial, and socio-cultural barriers\" that remain in place, even though services are ostensibly offered for free [\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e]. The identified \"critical cross-cutting issue\" of lack of patient transport is directly relevant to our findings. For caregivers of infants developing an abscess, the logistical and financial burden of travelling to a health facility can be a prohibitive first barrier, prompting a \"wait-and-see\" approach. Furthermore, documented experiences of out-of-pocket ancillary costs, nepotism, and perceived poor treatment by staff create a powerful disincentive to engage with the formal system [\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e]. In this environment, traditional medicine often serves as an accessible, affordable, and culturally acceptable first-line response, potentially explaining the extreme delays recorded before formal healthcare was sought.\u003c/p\u003e \u003cp\u003eThese local systemic barriers interact with the global evidence on AEFI management. International studies suggest that experiences with AEFIs can erode vaccine confidence, and that parents who seek care for AEFIs often hold more cautious attitudes toward immunization [\u003cspan class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e]. The Timor-Leste case illustrates a broader paradigm relevant to fragile health systems globally: when an AEFI occurs, it activates not just medical concern but also a calculus of access. The caregiver’s decision to delay formal care is often a rational response to anticipated logistical hardship, financial burden, and potential disrespect. Therefore, the prolonged delays documented here pose a multidimensional threat: to infant health through increased risk of severe infection, and to the immunization program through erosion of community trust. This risk is amplified in contexts where vaccine coverage is already suboptimal. Addressing this issue requires moving beyond AEFI reporting to actively managing the community experience of AEFIs—a lesson with direct applicability for other LMICs striving to maintain immunization confidence amidst systemic constraints..\u003c/p\u003e \u003cp\u003eFrontline healthcare workers (HCWs) play a pivotal role in this dynamic. Studies from similar low-resource settings, such as Uganda, indicate a common gap where HCWs may have theoretical knowledge of AEFIs but lack practical familiarity with reporting systems and, crucially, effective patient communication protocols [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e]. This knowledge-to-practice gap likely exists in Timor-Leste and has direct consequences. Without proficient skills in AEFI recognition, empathetic counseling, and clear guidance on when and where to seek care, HCWs are ill-equipped to mitigate the barriers described by the caregivers. Inadequate pre-vaccination counseling about common side effects, such as local reactions, leaves families unprepared, increasing alarm and potentially driving them towards informal care when such reactions occur.\u003c/p\u003e \u003cp\u003eOur study had several limitations. Although the sample size captured all reported serious abscess cases in 2024, it was small and limited the detailed subgroup analysis. Reliance on caregiver recall for dates introduces the potential for recall bias. Most significantly, our reliance on the national passive AEFI surveillance system means that we inherently miss cases where caregivers never sought formal care—precisely the population most affected by access barriers and likely to experience the longest delays. This selection bias suggests our findings, concerning as they are, may underestimate the true magnitude of delayed care-seeking and disengagement from the formal health system.\u003c/p\u003e "},{"header":"Conclusion and Recommendations","content":"\u003cp\u003eIn conclusion, this analysis quantifies a severe care-seeking delay for AEFIs within a fragile health system, using Timor-Leste as an illustrative case. The delay is a symptom of systemic barriers that deter timely help-seeking. To address this, a multi-pronged strategy is required, the principles of which are generalizable to comparable settings:\u003c/p\u003e\u003cp\u003eIntegrate AEFI management with access solutions: Community education must be coupled with practical support (e.g., transport mechanisms, community health worker follow-up) to overcome the primary logistical barriers that drive delays.\u003c/p\u003e\u003cp\u003eReframe healthcare worker training: Capacity building must extend beyond AEFI identification to include competency in empathetic communication, counseling, and trust-building to mitigate negative perceptions and guide appropriate care-seeking.\u003c/p\u003e\u003cp\u003eComplement passive surveillance with active safety-nets: Systems should incorporate active follow-up for serious AEFIs to identify disengaged families, turning surveillance into a protective intervention.\u003c/p\u003e\u003cp\u003eEmbed AEFI responses within broader health systems strengthening: Sustained improvement requires addressing foundational barriers—transport, financial protection, and quality of care—as part of universal health coverage agendas.\u003c/p\u003e\u003cp\u003eBy demonstrating how systemic failures translate into dangerous care-seeking delays, this study underscores that robust AEFI management is a cornerstone of both infant safety and immunization program resilience in fragile health systems worldwide.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003eHuman Ethics and Consent to Participate declarations: not applicable.\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThis research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eName Contribution(s)Filipe de Neri Machado Conceptualization, Methodology, SupervisionNoel Soares Gama Validation, Writing \u0026ndash; Original Draft PreparationNazario Barreto dos Santos Conceptualization, Data Curation, Project AdministrationBenigna Veneranda da Costa Amaral Formal Analysis, Writing \u0026ndash; Original Draft PreparationJimmi Bruno de Oliveira Software, Formal Analysis, VisualizationVenesia Tirana Guterres Methodology, Data Curation, Project AdministrationAloto Ximenes Belo Amaral Software, Writing \u0026ndash; Review \u0026amp; EditingDioneia Benevides Monteiro Validation, Writing \u0026ndash; Review \u0026amp; EditingMariano da Silva Marques Conceptualization, Methodology, SupervisionAll authors reviewed the manuscript\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eOrganization WH. Global progress report on HIV, viral hepatitis and sexually transmitted infections, 2021: accountability for the global health sector strategies 2016\u0026ndash;2021: actions for impact. World Health Organization; 2021.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWorld Health O. Hepatitis B vaccines: WHO position paper, July 2017 \u0026ndash; Recommendations. Vaccine. 2019;37(2):223\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOrganization WH. \u003cem\u003eCausality assessment of an adverse event following immunization (AEFI): user manual for the revised WHO classification.\u003c/em\u003e 2018.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen RT et al. The vaccine adverse event reporting system (VAERS). 1994. 12(6): pp. 542\u0026ndash;50.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBisetto LH, Ciosak SI. Analysis of adverse events following immunization caused by immunization errors. Rev Bras Enferm. 2017;70(1):87\u0026ndash;95.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrice JA, et al. I go I die, I stay I die, better to stay and die in my house: understanding the barriers to accessing health care in Timor-Leste. BMC Health Serv Res. 2016;16(1):535.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGrace R, Vaz J, Costa JD. Traditional medicine use in Timor-Leste. BMC Complement Med Ther. 2020;20(1):165.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eArkell P, et al. A population-representative serosurvey estimating vaccine-induced immunity against measles, rubella, hepatitis B and severe acute respiratory syndrome coronavirus 2 in Timor-Leste. The Lancet Regional Health - Southeast Asia; 2025. p. 34.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWorld Health O. \u003cem\u003eHepatitis B Vaccination Coverage for Timor-Leste\u003c/em\u003e. WHO Immunization Data portal 2026/01/09/ Accessed: 9 January 2026; Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://immunizationdata.who.int/global/wiise-detail-page/hepatitis-b-vaccination-coverage?CODE=TLS\u0026amp;ANTIGEN=HEPB_BD\u0026amp;YEAR\u003c/span\u003e\u003cspan address=\"https://immunizationdata.who.int/global/wiise-detail-page/hepatitis-b-vaccination-coverage?CODE=TLS\u0026amp;ANTIGEN=HEPB_BD\u0026amp;YEAR\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e=.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZwi A et al. \u003cem\u003eTimor-Leste Health Care Seeking Behaviour Study, Final Report\u003c/em\u003e. 2009.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKetema DB, et al. Individual- and community-level predictors of healthcare-seeking behaviour for acute respiratory tract infections among children under five in 29 low- and middle-income countries: a multilevel analysis. Public Health. 2024;237:71\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGust DA, et al. Parental Concerns and Medical-Seeking Behavior After Immunization. Am J Prev Med. 2006;31(1):32\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eParrella A, et al. Parental perspectives of vaccine safety and experience of adverse events following immunisation. Vaccine. 2013;31(16):2067\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWatyaba B, et al. Knowledge and reporting of adverse events following childhood immunization (AEFI) among health workers and caregivers at Mengo Hospital (2021), Kampala, Uganda: A mixed-methods study. PLOS Global Public Health. 2025;5(7):e0004827.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"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":"Adverse events following immunisation, Healthcare-seeking behaviour, Hepatitis B vaccine, Abscess, Timor-Leste","lastPublishedDoi":"10.21203/rs.3.rs-8704552/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8704552/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eAdverse events following immunisation (AEFI), such as injection-site abscesses, represent a critical but often neglected link in the immunisation cascade, especially in low-resource settings. While systemic barriers to healthcare are widely documented, quantitative evidence on how these barriers directly impact care-seeking for AEFIs\u0026mdash;and consequently threaten immunisation program credibility\u0026mdash;remains limited. This study examined care-seeking delays for abscesses following Hepatitis B birth dose (HepB-BD) administration in Timor-Leste as a case study of this global challenge.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis descriptive cross-sectional study was conducted using the 2024 AEFI surveillance line list of Timor-Leste. All reported cases of abscesses in infants (0\u0026ndash;12 months old) following HepB-BD were included in this study. The primary outcome was care-seeking delay, defined as the number of days between the caregiver's notice of the abscess and the first formal healthcare consultation. Data were analysed using descriptive statistical methods.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAmong 41 reported cases, the median care-seeking delay was 17 days (range: 1\u0026ndash;44 days). Only 36.6% of caregivers sought care within 10 days, whereas 43.9% delayed care-seeking beyond 20 days. Less than half of the infants (46.3%) received HepB-BD within 24 hours of birth.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe prolonged delays observed underscore a critical failure point in the immunisation continuum within fragile health systems, where logistical and financial barriers overwhelm caregivers\u0026rsquo; decision-making. This study provides quantitative evidence that AEFI management is not merely a clinical concern but a pivotal trust-building interface between communities and health systems. Interventions must integrate active community education, healthcare worker training in AEFI communication, and tangible support to overcome systemic access barriers, a strategy relevant for similar low-resource settings globally.\u003c/p\u003e","manuscriptTitle":"Substantial delays in care-seeking for post-vaccination abscesses: a threat to infant health and immunization trust in Timor-Leste","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-08 14:30:37","doi":"10.21203/rs.3.rs-8704552/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-03-14T19:51:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"227127131530484289759283565147990890291","date":"2026-03-06T07:07:31+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-05T15:44:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"301441368977849611392333040720886436593","date":"2026-02-26T10:18:09+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-25T18:22:35+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-02-05T11:37:02+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-04T03:39:16+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-04T03:37:51+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Public Health","date":"2026-01-27T01:19:23+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":"b946ea86-d601-47fa-a3bd-24c8b929a569","owner":[],"postedDate":"March 8th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-08T14:30:37+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-08 14:30:37","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8704552","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8704552","identity":"rs-8704552","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}