Predictors of Hepatitis B Vaccine Uptake among Healthcare Workers in Sokoto, Nigeria

Predictors of Hepatitis B Vaccine Uptake among Healthcare Workers in Sokoto, Nigeria | medRxiv /* */ /* */ <!-- <!-- /*! * yepnope1.5.4 * (c) WTFPL, GPLv2 */ (function(a,b,c){function d(a){return"[object Function]"==o.call(a)}function e(a){return"string"==typeof a}function f(){}function g(a){return!a||"loaded"==a||"complete"==a||"uninitialized"==a}function h(){var a=p.shift();q=1,a?a.t?m(function(){("c"==a.t?B.injectCss:B.injectJs)(a.s,0,a.a,a.x,a.e,1)},0):(a(),h()):q=0}function i(a,c,d,e,f,i,j){function k(b){if(!o&&g(l.readyState)&&(u.r=o=1,!q&&h(),l.onload=l.onreadystatechange=null,b)){"img"!=a&&m(function(){t.removeChild(l)},50);for(var d in y[c])y[c].hasOwnProperty(d)&&y[c][d].onload()}}var j=j||B.errorTimeout,l=b.createElement(a),o=0,r=0,u={t:d,s:c,e:f,a:i,x:j};1===y[c]&&(r=1,y[c]=[]),"object"==a?l.data=c:(l.src=c,l.type=a),l.width=l.height="0",l.onerror=l.onload=l.onreadystatechange=function(){k.call(this,r)},p.splice(e,0,u),"img"!=a&&(r||2===y[c]?(t.insertBefore(l,s?null:n),m(k,j)):y[c].push(l))}function j(a,b,c,d,f){return q=0,b=b||"j",e(a)?i("c"==b?v:u,a,b,this.i++,c,d,f):(p.splice(this.i++,0,a),1==p.length&&h()),this}function k(){var a=B;return a.loader={load:j,i:0},a}var l=b.documentElement,m=a.setTimeout,n=b.getElementsByTagName("script")[0],o={}.toString,p=[],q=0,r="MozAppearance"in l.style,s=r&&!!b.createRange().compareNode,t=s?l:n.parentNode,l=a.opera&&"[object Opera]"==o.call(a.opera),l=!!b.attachEvent&&!l,u=r?"object":l?"script":"img",v=l?"script":u,w=Array.isArray||function(a){return"[object Array]"==o.call(a)},x=[],y={},z={timeout:function(a,b){return b.length&&(a.timeout=b[0]),a}},A,B;B=function(a){function b(a){var a=a.split("!"),b=x.length,c=a.pop(),d=a.length,c={url:c,origUrl:c,prefixes:a},e,f,g;for(f=0;f<d;f++)g=a[f].split("="),(e=z[g.shift()])&&(c=e(c,g));for(f=0;f<b;f++)c=x[f](c);return c}function g(a,e,f,g,h){var i=b(a),j=i.autoCallback;i.url.split(".").pop().split("?").shift(),i.bypass||(e&&(e=d(e)?e:e[a]||e[g]||e[a.split("/").pop().split("?")[0]]),i.instead?i.instead(a,e,f,g,h):(y[i.url]?i.noexec=!0:y[i.url]=1,f.load(i.url,i.forceCSS||!i.forceJS&&"css"==i.url.split(".").pop().split("?").shift()?"c":c,i.noexec,i.attrs,i.timeout),(d(e)||d(j))&&f.load(function(){k(),e&&e(i.origUrl,h,g),j&&j(i.origUrl,h,g),y[i.url]=2})))}function h(a,b){function c(a,c){if(a){if(e(a))c||(j=function(){var a=[].slice.call(arguments);k.apply(this,a),l()}),g(a,j,b,0,h);else if(Object(a)===a)for(n in m=function(){var b=0,c;for(c in a)a.hasOwnProperty(c)&&b++;return b}(),a)a.hasOwnProperty(n)&&(!c&&!--m&&(d(j)?j=function(){var a=[].slice.call(arguments);k.apply(this,a),l()}:j[n]=function(a){return function(){var b=[].slice.call(arguments);a&&a.apply(this,b),l()}}(k[n])),g(a[n],j,b,n,h))}else!c&&l()}var h=!!a.test,i=a.load||a.both,j=a.callback||f,k=j,l=a.complete||f,m,n;c(h?a.yep:a.nope,!!i),i&&c(i)}var i,j,l=this.yepnope.loader;if(e(a))g(a,0,l,0);else if(w(a))for(i=0;i (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];var j=d.createElement(s);var dl=l!='dataLayer'?'&l='+l:'';j.src='//www.googletagmanager.com/gtm.js?id='+i+dl;j.type='text/javascript';j.async=true;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-P4HH5NV'); Skip to main content Home About Submit ALERTS / RSS Search for this keyword Advanced Search Predictors of Hepatitis B Vaccine Uptake among Healthcare Workers in Sokoto, Nigeria View ORCID Profile Suleiman Idris Ahmad , View ORCID Profile Khadeejah Liman Hamza , Yahya Mohammed , View ORCID Profile Sa’adatu Shinkafi , View ORCID Profile Abubakar Maiyaki , View ORCID Profile Nuhu Aliyu , View ORCID Profile Muhammad Shakir Balogun , View ORCID Profile Abdulhakeem Olorukooba , View ORCID Profile Chukwuma Umeokonkwo , Mustapha Umar Imam , Lubabatu Abdulazeez , Habila Yunana , Lawal Aminu , View ORCID Profile Kabir Sabitu doi: https://doi.org/10.1101/2025.06.22.25330077 Suleiman Idris Ahmad 1 Medical Research Council Unit the Gambia at London School of Hygiene and Tropical Medicine, 2 Nigeria Field Epidemiology and Laboratory Training Program , 3 Ahmadu Bello University Zaria , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Suleiman Idris Ahmad For correspondence: suleimanai001{at}gmail.com Khadeejah Liman Hamza 3 Ahmadu Bello University Zaria , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Khadeejah Liman Hamza Yahya Mohammed 4 Usmanu Danfodiyo University Sokoto , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site Sa’adatu Shinkafi 4 Usmanu Danfodiyo University Sokoto , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Sa’adatu Shinkafi Abubakar Maiyaki 4 Usmanu Danfodiyo University Sokoto , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Abubakar Maiyaki Nuhu Aliyu 5 State Ministry of Health Sokoto , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Nuhu Aliyu Muhammad Shakir Balogun 6 Africa Field Epidemiology Network Abuja , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Muhammad Shakir Balogun Abdulhakeem Olorukooba 3 Ahmadu Bello University Zaria , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Abdulhakeem Olorukooba Chukwuma Umeokonkwo 7 African Field Epidemiology Network Kampala , Uganda, Directorate of ICT Katsina , Nigeria Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Chukwuma Umeokonkwo Mustapha Umar Imam 4 Usmanu Danfodiyo University Sokoto , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site Lubabatu Abdulazeez 4 Usmanu Danfodiyo University Sokoto , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site Habila Yunana 2 Nigeria Field Epidemiology and Laboratory Training Program , Find this author on Google Scholar Find this author on PubMed Search for this author on this site Lawal Aminu 7 African Field Epidemiology Network Kampala , Uganda, Directorate of ICT Katsina , Nigeria Find this author on Google Scholar Find this author on PubMed Search for this author on this site Kabir Sabitu 3 Ahmadu Bello University Zaria , Nigeria , Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Kabir Sabitu Abstract Full Text Info/History Metrics Data/Code Preview PDF Abstract Background Hepatitis B virus (HBV) infection is a major occupational hazard for healthcare workers (HCWs) in Nigeria, a high-prevalence country. With the HBV vaccine only integrated into the national childhood immunization program in 2004, most current HCWs are potentially unvaccinated and unprotected. This study aimed to determine the hepatitis B vaccine uptake rate and identify its predictors among HCWs in Sokoto State, Nigeria. Methods An analytical cross-sectional study was conducted between January and March 2023. A total of 804 HCWs were selected from primary, secondary, and tertiary health facilities using a multistage sampling technique. Data on sociodemographic characteristics, knowledge, attitude, and vaccine uptake were collected via a structured questionnaire. Multivariate logistic regression was used to identify independent predictors of vaccine uptake. Results Only 35.5% (285/804) of HCWs reported receiving at least one dose of the hepatitis B vaccine. Of these, just 51.6% (147/285) were fully vaccinated with three or more doses. Significant positive predictors of uptake included having a positive attitude towards the vaccine (aOR: 1.84; 95% CI: 1.19-2.84) and an employer recommending the vaccine at employment (aOR: 1.85; 95% CI: 1.15-2.98). Negative predictors included being a health assistant (aOR: 0.15; 95% CI: 0.03-0.91), working in a tertiary facility (aOR: 0.47; 95% CI: 0.24-0.93), having poor knowledge of HBV (aOR: 0.22; 95% CI: 0.07-0.69), and the absence of institutional advocacy (aOR: 0.62; 95% CI: 0.30-0.72). Conclusion Hepatitis B vaccination coverage among HCWs in Sokoto is critically low, exposing them to significant occupational risk. There is an urgent need for health authorities and hospital management to implement mandatory vaccination policies, coupled with targeted educational programs for vulnerable cadres, to improve uptake and protect this vital workforce. Introduction Hepatitis B virus (HBV) infection is a significant global public health challenge. In 2015, the World Health Organisation (WHO) estimated that 257 million people were living with chronic HBV infection, which led to approximately 887,000 deaths, primarily from complications such as liver cirrhosis and hepatocellular carcinoma 2 . The WHO African Region has one of the highest prevalences of HBV, with an estimated 6.1% of the adult population infected 2 . In Nigeria, the burden is particularly high; a 2016 national survey reported an HBV prevalence of 12.2%, while the more recent Nigeria HIV/AIDS Indicator and Impact Survey (NAIIS) in 2020 found a prevalence of 8.1% 3 , □. HBV, a DNA virus from the hepadnaviridae family, is known to cause both acute and chronic hepatitis, which can progress to severe liver disease 1 . Healthcare workers (HCWs) represent a high-risk group for contracting HBV due to the nature of their work. Their clinical environment and frequent contact with patients’ blood and other potentially infectious body fluids make them particularly vulnerable to blood-borne pathogens□,□. HBV is highly infectious—more so than HIV—and can remain viable on environmental surfaces for at least seven days, posing a persistent threat in clinical settings where environmental cleaning may be suboptimal□. Globally, it is estimated that thirty-seven per cent of HBV infections are attributable to occupational exposure. Immunization remains the single most effective intervention for preventing HBV infection in susceptible individuals. The hepatitis B vaccine is safe and highly effective, offering 98% to 100% protection against the development of chronic infection and its complications 11 , 12 . Despite its availability, a critical gap in protection exists for a large segment of the Nigerian healthcare workforce. The HBV vaccine was not integrated into Nigeria’s National Programme on Immunization (NPI) for infants until 2004. Consequently, most HCWs currently in practice, being older than 18 years, would have missed the opportunity for vaccination during childhood. This has created a large, potentially susceptible adult population at high occupational risk. Compounding this issue is the lack of a formal national policy for the screening and mandatory vaccination of HCWs in Nigeria□. Given the low historical immunization coverage in Northern Nigeria and the unique vulnerability of the current healthcare workforce, understanding the factors that influence vaccine uptake is critical for developing effective public health strategies 1 □. Therefore, this study aimed to determine the hepatitis B vaccine uptake rate and identify the sociodemographic, institutional, and personal factors predicting its uptake among healthcare workers in Sokoto State, Nigeria. Methods Study Design and Setting This analytical cross-sectional study was conducted between January 16 and March 14, 2023, among healthcare workers (HCWs) in Sokoto State, located in Northwestern Nigeria. The state capital, Sokoto City, hosts a mix of public and private health facilities, including tertiary, secondary, and primary levels of care. At the time of the study, there was no formal vaccination program for HCWs in Sokoto State. Study Population and Sampling The study population comprised approximately 6,521 HCWs distributed across 86 health facilities within Sokoto City. The inclusion criteria encompassed all clinical healthcare workers (such as doctors, nurses, laboratory staff, and health officers) and health assistants working in both public and private facilities. Pharmacists and individuals who were unavailable during the study period were excluded. The sample size was calculated using the Cochran formula□ 1 , based on a hepatitis B vaccine uptake prevalence of 40.3% from a previous study in Sokoto 3 □, a 99% confidence level, a 3.5% margin of error, and a 10% non-response rate, yielding a target sample size of 893 participants. A multistage sampling technique was employed. In the first stage, health facilities were stratified by tier, and a proportionate number were randomly selected: ten primary, five secondary, and two tertiary facilities. In the second stage, HCWs within the selected facilities were chosen by balloting, with proportionate allocation based on the staff population of each facility. Of the 893 HCWs approached, 804 completed the questionnaire, resulting in a response rate of 90%. Data Collection and Instrument Data were collected using a standardized, pre-tested, and validated semi-structured questionnaire, which was administered by trained interviewers. The questionnaire gathered information on sociodemographic characteristics, knowledge and awareness of HBV, risk perception, attitudes towards the virus and vaccine, occupational exposure to HBV, and existing advocacy and employment policies at the health facilities. Data were collected electronically, and unique codes were assigned to each participant to ensure anonymity. Variables and Measurement The primary outcome variable was self-reported hepatitis B vaccine uptake, defined as having received at least one dose of the vaccine (’Yes’ or ’No’). Key independent variables included sociodemographic characteristics. Composite scores were created for knowledge, attitude, and risk perception. Knowledge was assessed using 15 questions, with scores categorized as ’Good’ (11-15), ’Fair’ (6-10), or ’Poor’ (0-5). Attitude and risk perception were measured using a 5-point Likert scale and categorized as ’Positive’ or ’Negative’ based on score distributions. Statistical Analysis Data were cleaned and analyzed using Epi Info. Descriptive statistics, including frequencies and proportions, were calculated to summarize the variables. Bivariate analysis using the Chi-square test was conducted to assess associations between independent variables and vaccine uptake. Subsequently, multivariate binary logistic regression was performed to identify independent predictors of vaccine uptake. Adjusted odds ratios (aOR) with their corresponding 95% confidence intervals (CI) were computed, and a p-value of <0.05 was considered statistically significant. Ethical Considerations The study was conducted in accordance with ethical standards, receiving clearance from the Sokoto State Ministry of Health (Ref: SMH/1580/V.IV) and the Usmanu Danfodiyo University Teaching Hospital, Sokoto (Ref: NHREC/30/012/2019). Permission was also obtained from the management of the selected health facilities. All participants provided written informed consent before the interviews. Participation was voluntary, and confidentiality was maintained by de-identifying all data. Results Sociodemographic Characteristics of Participants A total of 804 healthcare workers (HCWs) participated in the study. The median age of the respondents was 35 years (Interquartile Range: 28-43). A proportion of participants were female (54.6%, n=439), and most were married (66.4%, n=534). The most represented professional cadres were nurses and midwives (34.1%, n=274), followed by laboratory staff (24.5%, n=197) and health assistants (21.5%, n=173). A significant proportion of the HCWs worked in tertiary health facilities (62.7%, n=504), and the median duration of professional practice was 6 years (Interquartile Range: 2-13). Table 1 summarizes the sociodemographic characteristics of the study population. View this table: View inline View popup Download powerpoint Table 1: Sociodemographic Characteristics of Healthcare Workers in Sokoto State (n=804) Hepatitis B Vaccine Uptake The self-reported uptake of at least one dose of the hepatitis B vaccine was 35.5% (n=285). Among the 285 HCWs who had initiated vaccination, only 51.6% (n=147) reported having received three or more doses, constituting full vaccination. The primary motivation for vaccination among those who received it was a fear of contracting hepatitis B (77.2%). For the 519 unvaccinated participants, the most cited obstacle was not knowing where to get the vaccine (33.1%). Predictors of Hepatitis B Vaccine Uptake Table 2 presents the results of the multivariate logistic regression analysis, which identified several independent predictors of hepatitis B vaccine uptake. Factors that positively predicted vaccine uptake included being in the age group of 27-36 years (aOR: 2.33; 95% CI: 1.06-5.10) or 37-46 years (aOR: 2.44; 95% CI: 1.23-4.85) when compared to those aged 47 and older. HCWs who had a positive attitude towards the vaccine and its importance were more likely to be vaccinated (aOR: 1.84; 95% CI: 1.19-2.84). Furthermore, an employer recommending the need for the hepatitis B vaccine at the time of employment significantly increased the likelihood of uptake (aOR: 1.85; 95% CI: 1.15-2.98). View this table: View inline View popup Download powerpoint Table 2: Multivariate Logistic Regression of Predictors of Hepatitis B Vaccine Uptake Conversely, several factors were associated with lower odds of vaccination. HCWs who were single were less likely to be vaccinated than those who were married (aOR: 0.51; 95% CI: 0.29-0.87). When compared to doctors and dentists, health assistants were significantly less likely to have received the vaccine (aOR: 0.15; 95% CI: 0.03-0.91). Working in a tertiary health facility was associated with a lower likelihood of vaccination compared to working in a primary facility (aOR: 0.47; 95% CI: 0.24-0.93). Lastly, having poor knowledge about HBV (aOR: 0.22; 95% CI: 0.07-0.69) and working in an institution with no advocacy measures for vaccination (aOR: 0.62; 95% CI: 0.30-0.72) were also significant negative predictors. Discussion This study identified a critically low uptake of the hepatitis B vaccine among healthcare workers in Sokoto State, Nigeria, and uncovered key predictors influencing this trend. The findings indicate that despite a high-risk environment, a significant portion of the healthcare workforce remains unprotected against a major occupational hazard. The determinants of vaccine uptake were multi-faceted, involving a combination of individual factors like age and attitude, professional roles, and crucial institutional factors such as employer recommendations and the type of health facility. The self-reported vaccine uptake rate of 35.5% in our study is alarmingly low and underscores a significant public health issue. This rate is lower than that reported in several other African studies 23 , □□,□□. When compared with other research within Nigeria, our finding is lower than the 40.3% reported in a 2015 study in Sokoto and the 43.4% found in Calabar, yet higher than the 14.2% uptake documented in a study in Enugu 22 , 3 □,□□. This suggests that while low HBV vaccination coverage among HCWs is a widespread national problem, local factors may influence the exact rates. Furthermore, this uptake is markedly lower than the coverage seen in studies from Asia, Europe, and the Middle East highlighting a substantial gap in occupational health and safety practices in our setting 21 , □ 1 ,□ 2 ,□□. Our analysis identified that HCWs aged between 27 and 46 years were more than twice as likely to be vaccinated. This finding is consistent with studies from Ghana and Enugu, which also showed higher uptake in more established career-age groups □□,□□ . This may be attributable to increased awareness of occupational risks over time. As expected, a positive attitude towards the vaccine was a strong predictor of uptake, emphasizing that HCWs’ beliefs and perceptions are crucial targets for behavioral interventions. The most actionable finding is the powerful role of institutional prompts; an employer’s recommendation to vaccinate at the point of employment increased uptake by 85%. This finding, like a report from Pakistan, suggests that simple institutional cues to action may be more effective in driving behavior than relying on an individual’s internal motivation, such as fear of infection□ 2 . Conversely, several factors were associated with a lower likelihood of vaccination. Health assistants were 85% less likely to be vaccinated compared to doctors, pointing to a significant disparity in occupational health access and knowledge between different professional cadres. This finding contrasts with a Botswanan study that reported increased uptake in doctors and laboratory staff rather than health assistants□□. A particularly interesting and counter-intuitive finding was that working in a tertiary facility was a negative predictor of vaccine uptake. This may be due to factors such as higher workload and less time for personal health maintenance, a hypothesis supported by an Enugu study where ’lack of time’ was a major reason for non-vaccination□□. Finally, poor knowledge and the absence of institutional advocacy were also strong negative predictors, reinforcing that both individual awareness and a supportive workplace environment are essential for improving vaccination coverage. The findings of this study have direct implications for policy and practice. The low overall uptake demonstrates a clear failure to protect a high-risk population and calls for urgent intervention. The strong predictive power of an employer’s recommendation provides compelling evidence that making hepatitis B vaccination a mandatory condition of employment for HCWs would be a highly effective strategy. Furthermore, the significant knowledge gaps and the specific vulnerability of cadres like health assistants highlight the need for targeted, continuous education programs that go beyond simple awareness to address specific barriers and misconceptions. Hospital management has a critical role to play in fostering a culture of safety, implementing clear vaccination policies, and removing obstacles to access. This study has several strengths, including its large sample size, methodologically sound probability sampling, and the inclusion of a wide range of health facilities (public and private; primary, secondary, and tertiary), which enhances the generalizability of the findings within the study area. However, the study’s limitations must be considered. Its cross-sectional design means that causality cannot be established, and the reliance on self-reported vaccination status may be subject to recall bias. While the findings are robust for Sokoto state, their generalizability to all of Nigeria should be approached with caution. Conclusion In conclusion, this study reveals that the uptake of the hepatitis B vaccine among healthcare workers in Sokoto, Nigeria, is critically inadequate, leaving a vast majority of this high-risk group unprotected. Vaccine uptake is not driven by a single factor but is a complex issue influenced by a combination of individual, professional, and institutional determinants. Positive predictors such as employer recommendations and a positive attitude, alongside negative predictors like being a health assistant, having poor knowledge, and working in a tertiary facility, provide a clear roadmap for intervention. The findings underscore an urgent need for the implementation of robust, multi-level strategies, centered on mandatory institutional policies and targeted educational campaigns, to ensure the comprehensive protection of Nigeria’s healthcare workforce against this preventable occupational hazard. Declarations Ethics approval and consent to participate Ethical approval was obtained from the Sokoto State Ministry of Health Research Ethics Committee (Ref: SMH/1580/V.IV) and the Usmanu Danfodiyo University Teaching Hospital, Sokoto, Ethics Committee (Ref: NHREC/30/012/2019). Written informed consent was obtained from all participants prior to their inclusion in the study. All methods were carried out in accordance with relevant guidelines and regulations. Consent for publication Not applicable. Availability of data and materials All data produced in the study are available upon reasonable request to the corresponding author. Competing interests The author declares that they have no competing interests. Data Availability All data produced in the study are available upon reasonable request to the corresponding author. References 1. ↵ Uriel AJ , Martin P . Hepatitis Viruses . Encyclopedia of Microbiology [Internet ]. 1996 J an 1 [cited 2022 Feb 6]; 540 – 64 . Available from: https://www.ncbi.nlm.nih.gov/books/NBK7864/ 2. ↵ Hepatitis B [Internet] . [cited 2020 Sep 3]. Available from: https://www.who.int/news-room/fact-sheets/detail/hepatitis-b 3. ↵ The Journey to Hepatitis Elimination in Nigeria - Hepatitis B Foundation [Internet] . [cited 2020 Sep 3]. Available from: https://www.hepb.org/blog/journey-hepatitis-elimination-nigeria/ 4. Olayinka AT , Oyemakinde A , Balogun MS , Ajudua A , Nguku P , Aderinola M , et al. Seroprevalence of Hepatitis B infection in Nigeria: A national survey . American Journal of Tropical Medicine and Hygiene . 2016 Oct 1; 95 ( 4 ): 902 – 7 . OpenUrl Abstract / FREE Full Text 5. Azodo CC , Ehigiator O , Ojo MA . Occupational risks and hepatitis B vaccination status of dental auxiliaries in Nigeria . Medical Principles and Practice . 2010 ; 19 ( 5 ): 364 – 6 . OpenUrl PubMed 6. Pardee M . Diagnosis and Management of Hepatitis B and C . Vol. 54 , Nursing Clinics of North America . W.B. Saunders ; 2019 . p. 277 – 84 . OpenUrl PubMed 7. Hepatitis B : Practice Essentials, Background, Pathophysiology [Internet] . [cited 2021 Nov 24]. Available from: https://emedicine.medscape.com/article/177632-overview#a3 8. Hepatitis B Information | Division of Viral Hepatitis | CDC [Internet] . [cited 2020 Sep 3]. Available from: https://www.cdc.gov/hepatitis/hbv/index.htm 9. Okenwa UJ , Dairo MD , Bamgboye E , Ajumobi O . Maternal knowledge and infant uptake of valid hepatitis B vaccine birth dose at routine immunization clinics in Enugu State – Nigeria . Vaccine . 2020 Mar 10; 38 ( 12 ): 2734 – 40 . OpenUrl PubMed 10. Ophori EA , Tula MY , Azih A v., Okojie R , Ikpo EP . Current trends of immunization in Nigeria: Prospect and challenges . Vol. 42 , Tropical Medicine and Health. Japanese Society of Tropical Medicine ; 2014 . p. 67 – 75 . OpenUrl 11. ↵ Riccò M , Cattani S , Casagranda F , Gualerzi G , Signorelli C . Knowledge, attitudes, beliefs and practices of occupational physicians towards vaccinations of health care workers: A cross sectional pilot study in north-eastern Italy . Int J Occup Med Environ Health . 2017 ; 30 ( 5 ): 775 – 90 . OpenUrl PubMed 12. ↵ Aaron D , Nagu TJ , Rwegasha J , Komba E . Hepatitis B vaccination coverage among healthcare workers at national hospital in Tanzania: How much, who and why? BMC Infect Dis . 2017 Dec 20; 17 ( 1 ). 13. Tackling Hepatitis B in Africa: The First Nigerian Hepatitis Summit - Hepatitis B Foundation [Internet] . [cited 2022 Feb 5]. Available from: https://www.hepb.org/blog/tackling-hepatitis-b-africa-first-nigerian-hepatitis-summit/ 14. WHO . Epidemiological update: increasing mortality calls for action 03 . Global hepatitis report , 2017 . 2017; 7 – 20 . 15. Terrault NA , Lok ASF , McMahon BJ , Chang KM , Hwang JP , Jonas MM , et al. Update on prevention, diagnosis, and treatment of chronic hepatitis B: AASLD 2018 hepatitis B guidance . Hepatology . 2018 Apr 1; 67 ( 4 ): 1560 – 99 . OpenUrl CrossRef PubMed 16. Pinkbook: Hepatitis B | CDC [Internet] . [cited 2022 Feb 5]. Available from: https://www.cdc.gov/vaccines/pubs/pinkbook/hepb.html 17. Terrault NA , Bzowej NH , Chang KM , Hwang JP , Jonas MM , Murad MH . AASLD guidelines for treatment of chronic hepatitis B . Hepatology . 2016 Jan 1; 63 ( 1 ): 261 – 83 . OpenUrl CrossRef PubMed 18. WHO releases first-ever global guidance for country validation of viral hepatitis B and C elimination [Internet] . [cited 2023 Jul 1]. Available from: https://www.who.int/news/item/25-06-2021-who-releases-first-ever-global-guidance-for-country-validation-of-viral-hepatitis-b-and-c-elimination 19. Elimination of hepatitis by 2030 [Internet] . [cited 2023 Jul 1]. Available from: https://www.who.int/health-topics/hepatitis/elimination-of-hepatitis-by-2030#tab=tab_1 20. Hepatitis B Basics | HHS.gov [Internet] . [cited 2023 Jul 1]. Available from: https://www.hhs.gov/hepatitis/learn-about-viral-hepatitis/hepatitis-b-basics/index.html 21. ↵ Napolitano F , Bianco A , D’Alessandro A , Papadopoli R , Angelillo IF . Healthcare workers’ knowledge, beliefs, and coverage regarding vaccinations in critical care units in Italy . Vaccine . 2019 Oct 31; 37 ( 46 ): 6900 – 6 . OpenUrl PubMed 22. ↵ Kooffreh-Ada M , Okpokam D , Chukwudike E , Oku A , Ameh S , Effa E . Hepatitis B virus knowledge and vaccination status among health-care workers in Calabar, Nigeria . Nigerian Journal of Medicine . 2021 ; 30 ( 1 ): 79 . OpenUrl 23. ↵ Mursy SM elbager M , Mohamed SOO . Knowledge, attitude, and practice towards Hepatitis B infection among nurses and midwives in two maternity hospitals in Khartoum, Sudan . BMC Public Health . 2019 Nov 29; 19 ( 1 ). 24. Machmud PB , Glasauer S , Gottschick C , Mikolajczyk R. Knowledge , Vaccination Status , and Reasons for Avoiding Vaccinations against Hepatitis B in Developing Countries: A Systematic Review . Vaccines (Basel) [Internet ]. 2021 Jun 9 [cited 2022 Mar 11]; 9 ( 6 ). 25. A Gedefaw AM . Hepatitis B vaccine knowledge and vaccination status among health care workers of Bahir Dar City Administration, Northwest Ethiopia: a cross sectional study . BMC Infect Dis . 2015 Jan 31; 15 ( 1 ): 30 – 5 . OpenUrl CrossRef PubMed 26. AO Abiola Aakbalalqa . Prevalence of HBsAG, knowledge, and vaccination practice against viral hepatitis B infection among doctors and nurses in a secondary health facility in Lagos state, South-Western Nigeria . Pan Afr Med J . 2016 ; 26 : 158 – 62 . OpenUrl 27. Ojara M , Owomugisha G , Kibunga IS , Asio LG , Bwaga I , Nabugere T , et al. Knowledge, attitude and occupational risks to hepatitis b infection among health workers in Gulu Regional Referral Hospital, Northern Uganda: A cross-sectional study design . Pan African Medical Journal . 2021 May 1; 39 . 28. Quadri NS , Shah SM , Rodin H , Debes JD . Promoting hepatitis B awareness: Evaluating an educational approach through health care workers in Tanzania . Ann Glob Health . 2021 ; 87 : 1 – 6 . OpenUrl PubMed 29. Mahfouz M , Nguyen H , Tu J , Diaz CR , Anjan S , Brown S , et al. Knowledge and Perceptions of Hepatitis B and Hepatocellular Carcinoma Screening Guidelines Among Trainees: A Tale of Three Centers . Dig Dis Sci . 2020 Sep 1; 65 ( 9 ): 2551 – 61 . OpenUrl PubMed 30. Alsabaani A , Alqahtani NSS , Alqahtani SSS , Al-Lugbi JHJ , Asiri MAS , Salem SEE , et al. Incidence, Knowledge, Attitude and Practice Toward Needle Stick Injury Among Health Care Workers in Abha City, Saudi Arabia . Front Public Health . 2022 Feb 14; 10 . 31. Shah SM , Rodin H , Pogemiller H , Magbagbeola O , Ssebambulidde K , Zewde A , et al. Hepatitis B awareness and vaccination patterns among healthcare workers in Africa . American Journal of Tropical Medicine and Hygiene . 2020 Dec 1; 103 ( 6 ): 2460 – 8 . OpenUrl PubMed 32. Herrera-Restrepo O , Davis K , Sweeney C , Davenport E , Ghaswalla P , Buck PO . Hepatitis A and B vaccination in adults at risk: A survey of US healthcare providers’ attitudes and practices . Hum Vaccin Immunother . 2022 ; 18 ( 6 ). 33. Kirupakaran J , Meloche C , Upfal M . Practices and attitudes of Michigan-based occupational physicians regarding adult immunization . J Occup Environ Med . 2018 ; 60 ( 11 ): 1034 – 41 . OpenUrl PubMed 34. Liu Y , Ma C , Jia H , Xu E , Zhou Y , Zhang Z , et al. Knowledge, attitudes, and practices regarding hepatitis B vaccination among hospital-based doctors and nurses in China: Results of a multi-site survey . Vaccine [Internet ]. 2018 Apr 19 [cited 2023 Jun 15]; 36 ( 17 ): 2307 – 13 . OpenUrl 35. Roien R , Mousavi SH , Ozaki A , Baqeri SA , Hosseini SMR , Ahmad S , et al. Assessment of Knowledge, Attitude, and Practice of Health-Care Workers Towards Hepatitis B Virus Prevention in Kabul, Afghanistan . J Multidiscip Healthc [Internet ]. 2021 [cited 2023 Jun 15]; 14 : 3177 . OpenUrl 36. Abeje G , Azage M . Hepatitis B vaccine knowledge and vaccination status among health care workers of Bahir Dar City Administration, Northwest Ethiopia: a cross sectional study . BMC Infect Dis [Internet ]. 2015 Jan 31 [cited 2023 Jun 15]; 15 ( 1 ): 1 – 6 . OpenUrl 37. Akazong W E , Tume C , Njouom R , Ayong L , Fondoh V , Kuiate JR . Knowledge, attitude and prevalence of hepatitis B virus among healthcare workers: A cross-sectional, hospital-based study in Bamenda Health District, NWR, Cameroon . BMJ Open . 2020 Mar 18; 10 ( 3 ). 38. Pham TTH , Le TX , Nguyen DT , Luu CM , Truong BD , Tran PD , et al. Knowledge, attitudes and medical practice regarding hepatitis B prevention and management among healthcare workers in Northern Vietnam . PLoS One . 2019 Oct 1; 14 ( 10 ). 39. Hassan M *, Awosan KJ , Nasir S , Tunau K , Burodo A , Yakubu A , et al. Knowledge, risk perception and hepatitis B vaccination status of healthcare workers in Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria . J Public Health Epidemiol [Internet] . 2016 Apr 30 [cited 2023 Jun 15]; 8 ( 4 ): 53 – 9 . OpenUrl 40. Ibekwe RC , Ibeziako N . Hepatitis B vaccination status among health workers in Enugu, Nigeria . Niger J Clin Pract . 2006 ; 9 ( 1 ): 7 – 10 . OpenUrl PubMed 41. Abiodun O , Shobowale O , Elikwu C , Ogbaro D , Omotosho A , Mark B , et al. Risk perception and knowledge of hepatitis B infection among cleaners in a tertiary hospital in Nigeria: A cross-sectional study . Clin Epidemiol Glob Health . 2019 Mar 1; 7 ( 1 ): 11 – 6 . OpenUrl 42. Shrestha DB , Khadka M , Khadka M , Subedi P , Pokharel S , Thapa BB . Hepatitis B vaccination status and knowledge, attitude, and practice regarding Hepatitis B among preclinical medical students of a medical college in Nepal . PLoS One . 2020 Nov 1; 15 ( 11 November ). 43. Ngum AM , Laure SJ , Tchetnya X , Tambe TA , Ngwayu CN , Wirsiy FS , et al. Vaccination against Hepatitis B among health care workers in the Bamenda Health District: influence of knowledge and attitudes , Cameroon. Pan Afr Med J [Internet ]. 2021 Sep 1 [cited 2023 Jun 13]; 40 . 44. Akibu M , Nurgi S , Tadese M , Tsega WD i. Attitude and Vaccination Status of Healthcare Workers against Hepatitis B Infection in a Teaching Hospital, Ethiopia . Scientifica (Cairo) [Internet ]. 2018 [cited 2023 Jun 15]; 2018 . 45. Dayyab FM , Iliyasu G , Ahmad BG , Bako AT , Ngamariju SS , Habib AG . Hepatitis B vaccine knowledge and self-reported vaccination status among healthcare workers in a conflict region in northeastern Nigeria . Ther Adv Vaccines Immunother [Internet ]. 2020 [cited 2022 Aug 5]; 8 . 46. Oni OI , Osho OP , Oluwole MT , Osho ES , Ogungbeje A , Raji HM . Assessing the level of knowledge, uptake of hepatitis B virus vaccine, and its determinants among health workers across various levels of health facilities in Ondo, South West, Nigeria . The Egyptian Journal of Internal Medicine 2022 34:1 [Internet]. 2022 Nov 5 [cited 2023 Jun 15]; 34 ( 1 ): 1 – 10 . OpenUrl 47. Orji CJ , Chime OH , Ndibuagu EO . Vaccination status and prevalence of hepatitis B virus infection among health-care workers in a tertiary health institution, Enugu State, Nigeria . https://doi.org/101177/2010105820923681 [Internet]. 2020 May 13 [cited 2023 Jun 15]; 29 ( 2 ): 119 – 25 . 48. Implementation guide for vaccination of health workers [Internet] . [cited 2023 Jul 12]. 49. Ali AS , Hussein NA , Elmi EOH , Ismail AM , Abdi MM . Hepatitis B vaccination coverage and associated factors among medical students: a cross-sectional study in Bosaso, Somalia, 2021 . BMC Public Health [Internet] . 2023 Dec 1 [cited 2023 Jul 12]; 23 ( 1 ). 50. Ndunguru B , Wilfred D , Kapesa A , Kilonzo SD , Mirambo M , Hyera F , et al. Low uptake of hepatitis B vaccination among healthcare workers in primary health facilities in Mwanza region, North-Western Tanzania . Front Public Health [Internet ]. 2023 Jun 2 [cited 2023 Jul 12]; 11 . 51. Yuan Q , Wang F , Zheng H , Zhang G , Miao N , Sun X , et al. Hepatitis B vaccination coverage among health care workers in China . PLoS One . 2019 May 7; 14 ( 5 ). 52. Soomar SM , Siddiqui AR , Azam SI , Shah M . Determinants of hepatitis B vaccination status in health care workers of two secondary care hospitals of Sindh, Pakistan: a cross-sectional study . Hum Vaccin Immunother [Internet] . 2021 [cited 2023 Jun 13]; 17 ( 12 ): 5579 . OpenUrl 53. Wilson R , Zaytseva A , Bocquier A , Nokri A , Fressard L , Chamboredon P , et al. Vaccine hesitancy and self-vaccination behaviors among nurses in southeastern France . Vaccine . 2020 Jan 29; 38 ( 5 ): 1144 – 51 . OpenUrl PubMed 54. Baldolli A , Michon J , Verdon R , Fournier A . Vaccination perception and coverage among healthcare students in France in 2019 . BMC Med Educ . 2020 Dec 1; 20 ( 1 ). 55. Kisangau EN , Awour A , Juma B , Odhiambo D , Muasya T , Kiio SN , et al. Prevalence of hepatitis B virus infection and uptake of hepatitis B vaccine among healthcare workers, Makueni County, Kenya 2017 . Journal of Public Health (United Kingdom) . 2019 Dec 1; 41 ( 4 ): 765 – 71 . OpenUrl 56. Omotowo IB , Meka IA , Ijoma UN , Okoli VE , Obienu O , Nwagha T , et al. Uptake of hepatitis B vaccination and its determinants among health care workers in a tertiary health facility in Enugu, South-East, Nigeria . BMC Infect Dis [Internet ]. 2018 Jun 28 [cited 2022 Mar 11]; 18 ( 1 ). 57. Vrachnaki O , Vergadi E , Ioannidou E , Galanakis E . Determinants of low uptake of vaccination against influenza, measles, and hepatitis B among healthcare professionals in Greece: a multicenter cross-sectional study . Hum Vaccin Immunother . 2020 ; 16 ( 11 ): 2663 – 9 . OpenUrl PubMed 58. Shah SM , Rodin H , Pogemiller H , Magbagbeola O , Ssebambulidde K , Zewde A , et al. Hepatitis B Awareness and Vaccination Patterns among Healthcare Workers in Africa . Am J Trop Med Hyg [Internet ]. 2020 Oct 5 [cited 2023 Jul 4]; 103 ( 6 ): 2460 – 8 . OpenUrl 59. La Torre G , Scalingi S , Garruto V , Siclari M , Chiarini M , Mannocci A. Knowledge , Attitude and Behaviours towards Recommended Vaccinations among Healthcare Workers . Healthcare . 2017 Mar 7; 5 ( 1 ): 13 . OpenUrl PubMed 60. Pavithran V , Murali R , Krishna M , Shamala A , Yalamalli M , Kumar Av . Knowledge, attitude, and practice of needle stick and sharps injuries among dental professionals of Bangalore, India . J Int Soc Prev Community Dent . 2015 ; 5 ( 5 ): 406 . OpenUrl PubMed 61. Cochran WG . Sampling Techniques [Internet]. Third. Sampling Techniques . New York : John Wiley & Sons, Inc ; 1977 [cited 2023 Sep 18]. 62. Aroke D , Kadia BM , Anutebeh EN , Belanquale CA , Misori GM , Awa A , et al. Awareness and Vaccine Coverage of Hepatitis B among Cameroonian Medical Students . Biomed Res Int . 2018 ; 2018 . 63. Bilounga Ndongo C , Eteki L , Siedner M , Mbaye R , Chen J , Ntone R , et al. Prevalence and vaccination coverage of Hepatitis B among healthcare workers in Cameroon: A national seroprevalence survey . J Viral Hepat . 2018 Dec 1; 25 ( 12 ): 1582 – 7 . OpenUrl PubMed 64. Adamu A , Essoh TA , Adeyanju GC , Jalo RI , Saleh Y , Aplogan A , et al. Drivers of hesitancy towards recommended childhood vaccines in African settings: a scoping review of literature from Kenya, Malawi and Ethiopia . Expert Rev Vaccines . 2021 ; 20 ( 5 ): 611 – 21 . OpenUrl PubMed 65. Getnet MA , Bayu NH , Abtew MD , W Mariam TGM . & lt;p>Hepatitis B Vaccination Uptake Rate and Predictors in Healthcare Professionals of Ethiopia . Risk Manag Healthc Policy [Internet ]. 2020 Dec 8 [cited 2023 Jun 13]; 13 : 2875 – 85 . OpenUrl 66. Karaivazoglou K , Triantos C , Lagadinou M , Bikas C , Michailidou M , Kalafateli M , et al. Acceptance of hepatitis B vaccination among health care workers in Western Greece . Arch Environ Occup Health [Internet ]. 2014 [cited 2023 Sep 18]; 69 ( 2 ): 107 – 11 . OpenUrl 67. Kalemaki D , Karakonstantis S , Galanakis E , Lionis C . Vaccination coverage of general practitioners: a cross-sectional study from Greece . Public Health . 2020 Apr 1; 181 : 110 – 3 . OpenUrl PubMed 68. Clarke MA , Moore JL , Steege LM , Koopman RJ , Belden JL , Canfield SM , et al. Health information needs, sources, and barriers of primary care patients to achieve patient-centered care: A literature review . Health Informatics J . 2016 Dec 1; 22 ( 4 ): 992 – 1016 . OpenUrl CrossRef PubMed 69. Alduraywish SA , Altamimi LA , Aldhuwayhi RA , AlZamil LR , Alzeghayer LY , Alsaleh FS , et al. Sources of Health Information and Their Impacts on Medical Knowledge Perception Among the Saudi Arabian Population: Cross-Sectional Study . J Med Internet Res [Internet ]. 2020 Mar 1 [cited 2023 Sep 18]; 22 ( 3 ). 70. Ngekeng S , Chichom-Mefire A , Nde P , Nsagha D , Nkuigue A , Tiogouo K , et al. Hepatitis B Prevalence, Knowledge and Occupational Factors among Health Care Workers in Fako Division, South West Region Cameroon . Microbiol Res J Int . 2018 Apr 9; 23 ( 4 ): 1 – 9 . OpenUrl 71. Ansa GA , Ofori KNA , Houphouet EE , Amoabeng AA , Sifa JS , Amenuveve CK , et al. Hepatitis B vaccine uptake among healthcare workers in a referral hospital , Accra. Pan Afr Med J [Internet ]. 2019 [cited 2023 Sep 18];33. 72. Odusanya O . Hepatitis B Virus Vaccine: The Nigerian Story . Journal of the Obafemi Awolowo University Medical Student’s Association (IFEMED) [Internet ]. 2008 Sep 8 [cited 2020 Sep 3]; 14 ( 1 ). 73. P Bonani GB . Vaccination against hepatitis B in health care workers . Vaccione . 2001 Mar 21; 19 ( 17–19 ): 2389 – 94 . OpenUrl 74. Mcgrane J , Staines A . Nursing Staff Knowledge of the Hepatitis B Virus Including Attitudes and Acceptance of Hepatitis B Vaccination: Development of an Effective Program . Workplace Health Saf . 2003 Aug 1; 51 ( 8 ): 347 – 52 . OpenUrl 75. Botchway ET , Agyare E , Seyram L , Owusu KK , Mutocheluh M , Obiri-Yeboah D . Prevalence and attitude towards hepatitis B vaccination among healthcare workers in a tertiary hospital in Ghana . Pan Afr Med J [Internet ]. 2020 May 1 [cited 2023 Sep 18]; 36 : 1 – 11 . OpenUrl 76. Surofchy DD , Shieh N , Tam I . Evolving considerations for choice of hepatitis B vaccine . Am J Manag Care . 2023 Feb 1; 29 ( 1 ): S3 – 14 . OpenUrl PubMed 77. Machiya T , Burnett RJ , Fernandes L , François G , De Schryver A , van Sprundel M , et al. Hepatitis B vaccination of healthcare workers at the Princess Marina Hospital, Botswana . Int Health . 2015 Jul 1; 7 ( 4 ): 256 – 61 . OpenUrl CrossRef PubMed View the discussion thread. Back to top Previous Next Posted June 23, 2025. Download PDF Data/Code Email Thank you for your interest in spreading the word about medRxiv. NOTE: Your email address is requested solely to identify you as the sender of this article. Your Email * Your Name * Send To * Enter multiple addresses on separate lines or separate them with commas. You are going to email the following Predictors of Hepatitis B Vaccine Uptake among Healthcare Workers in Sokoto, Nigeria Message Subject (Your Name) has forwarded a page to you from medRxiv Message Body (Your Name) thought you would like to see this page from the medRxiv website. Your Personal Message CAPTCHA This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. Share Predictors of Hepatitis B Vaccine Uptake among Healthcare Workers in Sokoto, Nigeria Suleiman Idris Ahmad , Khadeejah Liman Hamza , Yahya Mohammed , Sa’adatu Shinkafi , Abubakar Maiyaki , Nuhu Aliyu , Muhammad Shakir Balogun , Abdulhakeem Olorukooba , Chukwuma Umeokonkwo , Mustapha Umar Imam , Lubabatu Abdulazeez , Habila Yunana , Lawal Aminu , Kabir Sabitu medRxiv 2025.06.22.25330077; doi: https://doi.org/10.1101/2025.06.22.25330077 Share This Article: Copy Citation Tools Predictors of Hepatitis B Vaccine Uptake among Healthcare Workers in Sokoto, Nigeria Suleiman Idris Ahmad , Khadeejah Liman Hamza , Yahya Mohammed , Sa’adatu Shinkafi , Abubakar Maiyaki , Nuhu Aliyu , Muhammad Shakir Balogun , Abdulhakeem Olorukooba , Chukwuma Umeokonkwo , Mustapha Umar Imam , Lubabatu Abdulazeez , Habila Yunana , Lawal Aminu , Kabir Sabitu medRxiv 2025.06.22.25330077; doi: https://doi.org/10.1101/2025.06.22.25330077 Citation Manager Formats BibTeX Bookends EasyBib EndNote (tagged) EndNote 8 (xml) Medlars Mendeley Papers RefWorks Tagged Ref Manager RIS Zotero Tweet Widget Facebook Like Google Plus One Subject Area Public and Global Health Subject Areas All Articles Addiction Medicine (568) Allergy and Immunology (863) Anesthesia (299) Cardiovascular Medicine (4425) Dentistry and Oral Medicine (443) Dermatology (382) Emergency Medicine (607) Endocrinology (including Diabetes Mellitus and Metabolic Disease) (1507) Epidemiology (15221) Forensic Medicine (30) Gastroenterology (1123) Genetic and Genomic Medicine (6588) Geriatric Medicine (667) Health Economics (997) Health Informatics (4524) Health Policy (1368) Health Systems and Quality Improvement (1612) Hematology (540) HIV/AIDS (1264) Infectious Diseases (except HIV/AIDS) (15910) Intensive Care and Critical Care Medicine (1103) Medical Education (623) Medical Ethics (145) Nephrology (667) Neurology (6588) Nursing (346) Nutrition (998) Obstetrics and Gynecology (1143) Occupational and Environmental Health (956) Oncology (3331) Ophthalmology (970) Orthopedics (369) Otolaryngology (420) Pain Medicine (435) Palliative Medicine (129) Pathology (663) Pediatrics (1690) Pharmacology and Therapeutics (691) Primary Care Research (710) Psychiatry and Clinical Psychology (5440) Public and Global Health (9219) Radiology and Imaging (2195) Rehabilitation Medicine and Physical Therapy (1369) Respiratory Medicine (1196) Rheumatology (593) Sexual and Reproductive Health (710) Sports Medicine (529) Surgery (710) Toxicology (99) Transplantation (289) Urology (265) (function(){function c(){var b=a.contentDocument||a.contentWindow.document;if(b){var d=b.createElement('script');d.innerHTML="window.__CF$cv$params={r:'9ffcb4bb2f88ad07',t:'MTc3OTQ2MjE4OQ=='};var a=document.createElement('script');a.src='/cdn-cgi/challenge-platform/scripts/jsd/main.js';document.getElementsByTagName('head')[0].appendChild(a);";b.getElementsByTagName('head')[0].appendChild(d)}}if(document.body){var a=document.createElement('iframe');a.height=1;a.width=1;a.style.position='absolute';a.style.top=0;a.style.left=0;a.style.border='none';a.style.visibility='hidden';document.body.appendChild(a);if('loading'!==document.readyState)c();else if(window.addEventListener)document.addEventListener('DOMContentLoaded',c);else{var e=document.onreadystatechange||function(){};document.onreadystatechange=function(b){e(b);'loading'!==document.readyState&&(document.onreadystatechange=e,c())}}}})();