Sexual and reproductive health knowledge and hepatitis B surface antigen prevalence among adolescents and young adults in Benguela Province, Angola: a pooled cross-sectional study

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In Angola, young people continue to face substantial SRH challenges, including early childbearing and a high burden of sexually transmitted infections (STIs), yet subnational data remain limited. Objective: To characterise SRH knowledge, sexual behaviours, and STI profiles among adolescents and young adults aged 15–25 years in Benguela Province, Angola. Methods: We conducted a pooled cross-sectional analysis of two independent community-based surveys carried out in 2021 and 2024 in four municipalities of Benguela Province. Participants were recruited through outreach activities in public and community settings. SRH knowledge was assessed using a structured questionnaire, and point-of-care testing was offered for HIV (Alere Determine HIV1/2 antibodies, Abbott), hepatitis B surface antigen (HBsAg) (HBsAg, Nantong diagnosis Biotech-nology), hepatitis C virus (HCV), and syphilis (Treponema pallidum antibodies, Nantong Diagnos Biotechnology). Due to substantial sociodemographic differences between survey rounds, data were pooled and analysed as a single cross-sectional dataset. Multivariate logistic regression was used to identify factors associated with adequate SRH knowledge and HBsAg positivity. Results: A total of 2,802 adolescents and young adults were included. Adequate SRH knowledge was significantly associated with older age, higher educational attainment, and urban residence. While the prevalence of HIV, syphilis, and HCV was low, a high proportion of participants tested positive for HBsAg. HBsAg positivity was more frequent among males and among participants residing in Cubal and Benguela municipalities. Conclusions: Important inequalities in SRH knowledge persist among adolescents and young adults in Benguela Province, particularly affecting younger, with lower education level, and rural populations. The high proportion of HBsAg positivity highlights the need to strengthen hepatitis B prevention strategies, including catch-up vaccination, expanded screening, and integration of HBV services into youth-friendly SRH programmes. These findings underscore the importance of equitable access to SRH information and services to reduce preventable health risks among young people in Angola. Sexual and reproductive health knowledge Sexually transmitted infections Adolescents and young adults Introduction Sexual and reproductive health (SRH) is a fundamental component of overall health and well-being. Adequate knowledge in this area is essential to promote gender equality, prevent unintended pregnancies and sexually transmitted infections (STIs), and ensure informed decision-making, especially among adolescents and young adults. Adolescence is a period marked by increased vulnerability in sexual behavior, making access to information and education critical (1–3). Early and comprehensive sexuality education has been recognized as a key strategy for improving outcomes in this domain (4) In many low- and middle-income countries, access to SRH education remains limited (5). Barriers such as limited access to formal education, restricted internet connectivity, and cultural or societal resistance to open discussion of sexuality and reproductive rights continue to shape young people’s exposure to reliable information (6–8). Although several studies from sub-Saharan Africa, including Angola, have reported moderate to good overall levels of SRH knowledge among adolescents and young adults, this knowledge is not evenly distributed (9–11). Persistent disparities according to education level, place of residence, and access to information remain evident (12,13). and adequate knowledge alone may be insufficient to prevent adverse SRH outcomes in settings with limited access to services and preventive interventions. Angola, a country in southwestern Africa, continues to face significant SRH challenges among its youth population. National estimates indicate that approximately 26–30% of girls aged 15–19 years have already begun childbearing, a proportion substantially higher than the sub-Saharan African average (14,15). Gender norms, including early union formation, unequal power dynamics, and stigma surrounding contraceptive use, may further constrain young people’s autonomy and their ability to translate knowledge into effective preventive behaviours (16–18). The epidemiology of STIs also remains an important concern. Angola is classified as a high-endemicity country for hepatitis B virus (HBV), with national estimates ranging between 8% and 15%(19). Although HBV vaccination was introduced into the national immunization schedule in 2006, vaccination gaps, irregular early-childhood coverage, and limited screening among adolescents and young adults may contribute to ongoing transmission. Recent evidence from sub-Saharan Africa underscores that HBV remains one of the most significant yet under-recognized infectious disease threats among youth (20,21). However, data on HBV infection among adolescents and young adults in Angola, particularly at the subnational level, remain scarce. In response to these challenges, the FUTURO Project, funded by the European Union, was implemented to strengthen SRH knowledge, behaviours, and policy engagement among adolescents and young adults through a multilevel communication and education strategy in selected municipalities of Benguela Province. Two cross-sectional surveys were conducted in 2021 and 2024 as part of the project. Although the original intention was to assess changes in SRH knowledge over time, direct comparisons between the two survey rounds were not methodologically appropriate, as they were based on independent samples with substantial differences in age distribution, educational attainment, and place of residence. In addition, exploratory analyses suggested that broader contextual or structural factors were influencing SRH indicators over time. To avoid potentially misleading interpretations, data from both survey rounds were therefore pooled for analysis. The objective of this study was to characterise sexual and reproductive health knowledge, sexual behaviours, and sexually transmitted infection profiles among adolescents and young adults aged 15–25 years in Benguela Province, Angola. Methods Study Design and Population We conducted a pooled cross-sectional analysis of data collected from adolescents and young adults aged 15 to 25 years. The study included participants from two urban municipalities (Benguela and Lobito) and two rural municipalities (Cubal and Caimbambo). This classification was based on the administrative designation and level of urbanization of the municipalities according to provincial territorial characteristics. Data were collected during two independent survey rounds conducted in 2021 and 2024, using the same study protocol and instruments previously published (22) . Participants were recruited through community outreach activities in public spaces, youth centres and churches (23–25) . Study Population Eligible participants were adolescents and young adults aged 15–25 years residing in the selected municipalities. Exclusion criteria were: (1) refusal or inability to provide informed consent; and (2) having participated in the design or implementation of FUTURO Project activities, to avoid direct exposure bias. Recruitment and Data Collection Procedures Prior to data collection, study objectives and procedures were presented to local authorities to facilitate community acceptance and mobilisation. Trained fieldworkers conducted outreach activities in public and community settings. The questionnaire was administered in a semi-assisted approach. A trained member of the research team explained each question to ensure comprehension. Participants then completed the questionnaire independently, with the option to request clarification if needed. No personally identifiable information was collected, and all questionnaires were completed anonymously. To ensure data quality, supervisors checked all completed forms daily for inconsistencies or missing responses. Double-entry verification was performed during digitalization. Data were collected and managed using the REDCap secure web platform (26). Structured Questionnaire and STI Testing We used the same structured questionnaire as in the baseline study (described elsewhere) (22). The tool consisted of 25 questions divided into four thematic sections: general sexual health knowledge, HIV, contraceptive methods and gender equity. For each section, knowledge was classified as “adequate” if at least two-thirds of the questions were answered correctly. An overall score of 17 or more correct answers (out of 25) was defined as adequate general knowledge (27) . This cut-off aligns with established practices in SRH knowledge assessments (28,29). Following questionnaire completion, participants were offered point-of-care testing for four STIs using validated rapid diagnostic tests: HIV (Alere Determine HIV 1/2, Abbott), hepatitis B virus (HBV) (HBsAg, Nantong diagnosis Biotechnology), hepatitis C virus (HCV) (antibodies against HCV, Nantong diagnosis Biotechnology), and syphilis (Treponema pallidum antibodies, Nantong diagnose Biotechnology). Testing was conducted in private spaces by trained staff from the Faculty of Medicine at Katyavala Bwila University. Finger-prick blood samples were used according to manufacturer instructions. Participants with positive test results received post-test counselling and were referred to pre-identified health units for confirmatory diagnosis and follow-up care. Sample Size Calculation The sample size for this study was originally determined with the aim of evaluating changes in SRH knowledge following the implementation of the FUTURO Project. The project aimed to increase SRH knowledge among adolescents and young adults in Benguela Province by 20%. Due to the lack of national data on SRH knowledge in Angola, estimates from other sub-Saharan African countries were used for reference. It was assumed that approximately 40% of the youth population would have adequate SRH knowledge at baseline. Based on this assumption, and considering a 95% confidence level (α = 0.05) and 80% power, a minimum of 1.400 participants was required to detect a 20% increase in knowledge over time. Although the current analysis does not seek to assess the intervention effect over time—due to the demographic differences between the two independent samples—the same sampling strategy was retained in the second round of data collection (2024), allowing for a consistent number of participants and proportional representation across municipalities. The sample was distributed according to the population size of each municipality using data from the 2014 Angolan census, resulting in target recruitment of approximately 605 individuals from Benguela (43.2%), 371 from Lobito (26.5%), 329 from Cubal (23.5%), and 95 from Caimbambo (6.8%). Data Analysis Data were analysed with SPSS software. Descriptive statistics were calculated for all variables. Categorical variables were described using absolute frequencies and percentages, while continuous variables were summarized using either the mean and standard deviation (SD) or the median and interquartile range (IQR), depending on the distribution of the data. Due to sociodemographic differences between the 2021 and 2024 samples, direct temporal comparisons were not conducted. Instead, data from both rounds were pooled for a global analysis of SRH knowledge, and STIs prevalence. We conducted bivariate and multivariate analyses to explore factors associated with adequate overall SRH knowledge. Given the clear predominance of HBV infection among all STIs detected, we focused our analysis on this outcome. Therefore, an additional set of bivariate and multivariate analyses was carried out to identify factors independently associated with HBV infection. Independent variables included age, sex, education level, and municipality of residence (urban vs rural). Categorical variables were compared using the Chi-square test, and continuous variables using the t-test or Mann–Whitney U test, depending on distribution. Logistic regression models were used for multivariate analysis. A p-value < 0.05 was considered statistically significant. Justification for Pooling Data The primary objective of this study was to characterise SRH knowledge, sexual behaviours, and STIs profiles among adolescents and young adults in Benguela Province, rather than to evaluate longitudinal changes or intervention impact. In addition, substantial demographic differences were observed between the two independent survey samples, limiting the validity of direct temporal comparisons. For these reasons, data from the 2021 and 2024 surveys were pooled to increase statistical power and improve the representativeness of the overall analysis. Results A total of 2.802 individuals were included in the pooled analysis: 1.400 participants from the 2021 survey and 1.402 from 2024. Overall, 1.062 participants (37.6%) were female. The distribution by municipality was as follows: 190 (6.7%) from Caimbambo, 658 (23.3%) from Cubal, 1.213 (42.9%) from Benguela, and 741 (26.2%) from Lobito. The mean age of participants was 19.0 (SD: 0.48) years. Regarding education level, 12 participants (0.4%) reported having no formal education, 141 (5.0%) had completed primary education, 1.095 (38.7%) secondary education, and 154 (5.4%) higher education. Sexual Behaviour and STIs Prevalence A total of 1.868 participants (66.7%) reported having had previous sexual intercourse, with a mean age at first sexual encounter of 18.7 (SD: 2.4) years. Additionally, 237 individuals (8.5%) reported either having being pregnant (among females) or having caused a pregnancy (among males) before the age of 19. Regarding STIs, serological testing revealed that 33 participants (1.2%) were positive for HIV, 979 (34.9%) tested positive for HBsAg, 15 (0.5%) for HCV, and 27 (1.0%) for syphilis. When analysing factors associated with adequate SRH knowledge, we found that older age (OR 1.19 95%CI 1.07-1.17, p < 0.001), higher education level (OR14.11 (95%CI 3.58-55.59), p< 0.001), and living in an urban area (OR 5.51, 95%CI 4.17-7.26, p<0.001) were significantly associated with adequate overall knowledge. This information is summarized in Table 1. When analysing variables associated with HBV infection, we found that infection was significantly more frequent among males (OR 1.37, 95% CI: 1.14–1.65; p = 0.001), participants living in Cubal (OR 1.69, 95% CI: 1.30–2.18; p < 0.001) or Benguela (OR 2.11, 95% CI: 1.69–2.65; p < 0.001), compared to those residing in Lobito. Additionally, HBV infection was more common among individuals surveyed in 2024 compared to those surveyed in 2021 (OR 8.77, 95% CI: 7.15–10.50; p < 0.001). Table 2 summarizes the factors independently associated with HBV infection. Discussion In this large population-based study of over 2,800 adolescents and young adults from Benguela Province, Angola, overall sexual and reproductive health (SRH) knowledge was higher among older individuals, those with higher educational attainment, and those living in urban settings. Notably, we identified an alarmingly high prevalence of HBsAg positivity in this population. The observed associations between SRH knowledge and age, education level, and urban residence are consistent with previous studies from sub-Saharan Africa, which have shown that access to formal education, digital literacy, and proximity to health and information services strongly influence SRH knowledge and awareness (27) Urban adolescents and young adults are more likely to benefit from school-based programmes, online resources, and public health campaigns, whereas young people living in rural areas continue to face structural barriers related to limited connectivity, lower school attendance, and fewer youth-friendly services. These findings reinforce the persistence of intra-country inequalities in access to SRH information, even in settings where overall knowledge levels may be moderate to good. Despite the overall low prevalence of HIV, syphilis, and HCV, the proportion of participants testing positive for HBsAg was higher than expected compared with most published estimates for adolescents and young adults in sub-Saharan Africa. (19). This finding suggests a potentially high burden of HBV infection in the study population , but should be interpreted with caution. As hepatitis B testing was offered free of charge within the framework of a community-based project, participation may have been higher among individuals with perceived risk, prior exposure, or limited access to routine healthcare services (30–32). Consequently, the observed HBsAg positivity may reflect a higher-risk subpopulation rather than the true prevalence of HBV infection in the general adolescent and young adult population. This self-selection could have contributed to an overestimation of HBV prevalence. This interpretation is further supported by the higher prevalence of HIV observed in the 2024 survey, suggesting the inclusion of individuals with a higher underlying risk profile. Although the prevalence of HIV, syphilis, and HCV was relatively low overall, HIV prevalence was higher in the 2024 survey compared to the 2021 round. A substantial proportion of participants also tested positive for HBV, particularly among males and those residing in the municipalities of Cubal and Benguela. HBV screening was based on a single rapid diagnostic test for HBsAg without confirmatory serological testing. Although such tests are widely used in field and resource-limited settings, false-positive results cannot be excluded. Confirmatory testing, including HBV DNA quantification or additional serological markers such as Hepatitis B core antibody (anti-HBc), was not performed; therefore, the results should be interpreted as screening-based HBsAg positivity rather than confirmed HBV infection. The higher HBsAg positivity observed in 2024 compared to 2021 may partly reflect differences in the composition of the study population. Notably, the higher HIV prevalence in 2024 (measured using a widely validated and WHO-recommended assay) suggests a shift toward a higher-risk sample. This potential selection bias toward more vulnerable individuals may have contributed to the increased HBsAg positivity. Several factors may contribute to the substantial burden of HBV infection detected in this study. First, gaps in hepatitis B vaccination coverage may play an important role. Although the HBV vaccine was introduced into the Angolan national immunization schedule in 2006, adolescents and young adults included in this study may not have fully benefited from routine infant vaccination, particularly those born during the early years of vaccine rollout or residing in rural or underserved areas (21) . Second, vertical and early horizontal childhood transmisión, common in high-endemicity settings as Angola, result in chronic infection persisting into adolescence and young adulthood (33–35) . Limited access to routine screening and healthcare services may further contribute to a high proportion of undiagnosed infections (36,37). The higher prevalence of HBsAg positivity observed among males may reflect gender-specific differences in exposure risks, healthcare-seeking behaviour, or engagement with preventive services. Similarly, the geographic differences observed across municipalities suggest that local contextual factors, such as access to health services, vaccination coverage, or socio-economic conditions, may influence HBV transmission and detection (38). Although participants surveyed in 2024 were more likely to test positive for HBsAg than those surveyed in 2021, this association should not be interpreted as evidence of a true temporal increase in HBV prevalence. The two survey rounds were based on independent samples with substantial differences in age distribution, educational attainment, and place of residence. Moreover, exploratory analyses indicated that several SRH indicators worsened over time even in municipalities where no intervention activities were implemented. These patterns suggest that broader contextual or structural factors, rather than the intervention itself, were likely influencing observed differences between survey rounds. Consequently, conducting a direct pre–post comparison or attributing changes over time to the FUTURO Project would not have been methodologically appropriate. Despite these limitations, the findings highlight a potentially under-recognised burden of HBV infection among adolescents and young adults in Benguela Province. Even under conservative assumptions, the results underscore the need to strengthen HBV prevention and control strategies in this population. Targeted catch-up vaccination campaigns for adolescents and young adults, particularly in high-prevalence municipalities such as Cubal and Benguela, should be considered. In addition, integrating HBV screening and counselling into youth-friendly sexual and reproductive health services may facilitate earlier diagnosis and linkage to care. Finally, although overall SRH knowledge was not low, persistent inequalities by education level and place of residence highlight the need for continued investment in equitable, community-based education strategies. Improving access to accurate SRH information, alongside strengthening vaccination, screening, and youth-friendly health services, will be essential to reduce preventable SRH risks and address the long-term burden of HBV infection among young people in Angola. Strengths and Limitations This study has several strengths. First, it includes a large sample of adolescents and young adults (over 2,800 participants), making it one of the largest population-based analyses of SRH knowledge and STI prevalence conducted in Angola to date. Second, data were collected using a standardized methodology and an identical survey instrument in both rounds, enabling comparability and enhancing internal consistency. Third, the inclusion of point-of-care testing for four major STIs adds objective biological measures that complement self-reported behaviours, which are often affected by social desirability bias. Finally, the study covers both urban and rural municipalities, allowing for meaningful identification of intra-provincial disparities. However, several limitations should be acknowledged. The cross-sectional design prevents establishing causal relationships. In addition, the two survey rounds were based on independent samples with different sociodemographic characteristics, limiting their suitability for pre–post or impact evaluation. For this reason, the study was not designed to assess temporal changes or intervention effects. Sexual behaviour data were self-reported and may be affected by recall or social desirability bias. Recruitment through community-based outreach represents a form of convenience sampling and may limit representativeness, although the large sample size and broad geographic coverage partially mitigate this concern. In addition, the provision of free point-of-care STIs testing may have preferentially attracted individuals with perceived risk of infection, potentially leading to an overestimation of prevalence, particularly for HBV. Finally, although validated rapid diagnostic tests were used for STIs screening, confirmatory laboratory testing was not conducted, which may have resulted in some degree of misclassification, especially for HBV infection. Conclusion This study provides a comprehensive overview of SRH knowledge, sexual behaviours, and STI prevalence among adolescents and young adults in Benguela Province, Angola. SRH knowledge was generally higher among older, more educated, and urban youth, reflecting persistent inequalities affecting rural and lower-education populations. The exceptionally high prevalence of HBV infection underscores the urgent need for targeted HBV prevention, catch-up vaccination, and expanded screening strategies for young people. While the prevalence of HIV, syphilis, and HCV was low overall, HIV prevalence was higher in the 2024 survey compared to the 2021 round, suggesting potential differences in the underlying risk profile of the study population. In addition, a notable proportion of participants tested positive for HBsAg. Although these findings suggest a potentially important burden of HBV infection among adolescents and young adults, they should be interpreted with caution, as results reflect screening-based HBsAg positivity and may be influenced by selection bias and the absence of confirmatory testing. These results underscore the need to strengthen HBV prevention and control strategies targeting young people, including catch-up vaccination, expanded screening, and integration of HBV services into youth-friendly sexual and reproductive health programmes. Improving equitable access to SRH information and services, particularly for rural and lower-education populations, should remain a public health priority. Further research using confirmatory testing and longitudinal designs is needed to better characterise HBV epidemiology and inform effective prevention strategies in Angola. Declarations Acknowledgements We thank all adolescents and young adults who participated in the surveys, as well as community leaders and municipal health authorities in Benguela Province for their support. We acknowledge the fieldworkers and laboratory technicians from the Faculty of Medicine at Katyavala Bwila University for their crucial role in data collection and STI testing. Conflict of interest The authors have no competing interests to declare that are relevant to the content of this article. Clinical Trial Clinical trial number: not applicable. Funding This study was conducted as part of the FUTURO Project, funded by the European Union. The funder had no role in the design, data collection, analysis, interpretation, or decision to submit the manuscript. Ethical Statement The study was designed, implemented, and reported in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice guidelines. The study protocol was reviewed and approved by the Ethics Committee of the Ministry of Health of the Republic of Angola (MINSA) (approval number: nº14/2021). Participation was voluntary. Written informed consent was obtained from all participants aged 18 years or older. For participants younger than 18 years, written informed consent was obtained from parents or legal guardians, and assent was obtained from the adolescents when appropriate according to their age and level of understanding. No personally identifiable information was collected, and all data were handled anonymously and confidentially. Sources of funding Study funded by the European Union (EuropeAid/162494/DD/ACT). Availability of data and materials Raw data were generated at Hospital Vall d’Hebron. Derived data supporting the findings of this study are available from the corresponding author [E.E] on request Implications for Policy and Practice The findings from this study have several important implications for public health policy and clinical practice in Angola. The exceptionally high prevalence of hepatitis B virus (HBV) among adolescents and young adults highlights the need to strengthen national vaccination strategies through catch-up vaccination campaigns targeting those who may not have benefited from routine infant immunisation, especially in high-prevalence municipalities such as Cubal and Benguela. Integrating HBV screening and counselling into youth-friendly health services is essential to facilitate early diagnosis and linkage to care. Addressing persistent inequalities in sexual and reproductive health (SRH) knowledge will require expanding community-based education programmes and improving access to accurate information through schools, community networks, and digital platforms where possible. Ensuring confidentiality and reducing stigma in health facilities may improve adolescents’ willingness to seek SRH care, including HBV testing and counselling. Promoting the engagement of young men is also crucial, given their higher HBV prevalence and lower health-seeking behaviour. Finally, strengthening STI surveillance systems, including routine monitoring of HBV, HIV, syphilis, and hepatitis C, will support more effective resource allocation and evaluation of public health interventions over time. Together, these actions could contribute to more equitable and effective SRH programmes and support Angola’s broader efforts to improve adolescent and youth health outcomes. References Wondimagegne YA, Anbese AT. 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Solomon-Rakiep T, Olivier J, Amponsah-Dacosta E. Towards contextualized complex systems approaches to scaling-up hepatitis B birth-dose vaccination in the African region: a qualitative systematic review. Front Public Health. 2024 Oct 24;12. McNaughton AL, Lourenço J, Bester PA, Mokaya J, Lumley SF, Obolski U, et al. Hepatitis B virus seroepidemiology data for Africa: Modelling intervention strategies based on a systematic review and meta-analysis. PLoS Med. 2020 Apr 21;17(4):e1003068. Peliganga LB, Horta MAP, Lewis-Ximenez LL. Enduring Challenges despite Progress in Preventing Mother-to-Child Transmission of Hepatitis B Virus in Angola. Pathogens. 2022 Feb 8;11(2):225. Tables Tables are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Table1VariablesassociatedwithadequateSSRknowledge.docx Table2VariablesassociatedwithHBVinfection.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 04 May, 2026 Reviewers agreed at journal 04 May, 2026 Reviewers agreed at journal 30 Apr, 2026 Reviewers invited by journal 17 Apr, 2026 Editor invited by journal 09 Apr, 2026 Editor assigned by journal 08 Apr, 2026 Submission checks completed at journal 08 Apr, 2026 First submitted to journal 02 Apr, 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-9301377","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":624997700,"identity":"1b806949-3302-4808-85e3-4c7a4c1ab754","order_by":0,"name":"Esperanza 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09:53:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9301377/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9301377/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108490804,"identity":"ff9997b7-032f-43f1-9ff6-1624fde0cb82","added_by":"auto","created_at":"2026-05-05 09:48:45","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":211653,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9301377/v1/4598a992-9238-4833-add3-84d10ab4d733.pdf"},{"id":107773445,"identity":"6030bba4-c22e-4e80-8aa9-dee49f2870c9","added_by":"auto","created_at":"2026-04-25 05:46:27","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":13931,"visible":true,"origin":"","legend":"","description":"","filename":"Table1VariablesassociatedwithadequateSSRknowledge.docx","url":"https://assets-eu.researchsquare.com/files/rs-9301377/v1/800db499ea2e33ae99be95fa.docx"},{"id":107869976,"identity":"0c805da1-ed08-45fe-ad1f-3b44843394bd","added_by":"auto","created_at":"2026-04-27 07:38:34","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":15090,"visible":true,"origin":"","legend":"","description":"","filename":"Table2VariablesassociatedwithHBVinfection.docx","url":"https://assets-eu.researchsquare.com/files/rs-9301377/v1/ad4e369e77778e99eaa4f9db.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Sexual and reproductive health knowledge and hepatitis B surface antigen prevalence among adolescents and young adults in Benguela Province, Angola: a pooled cross-sectional study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSexual and reproductive health (SRH) is a fundamental component of overall health and well-being. Adequate knowledge in this area is essential to promote gender equality, prevent unintended pregnancies and sexually transmitted infections (STIs), and ensure informed decision-making, especially among adolescents and young adults. Adolescence is a period marked by increased vulnerability in sexual behavior, making access to information and education critical (1\u0026ndash;3). Early and comprehensive sexuality education has been recognized as a key strategy for improving outcomes in this domain (4)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn many low- and middle-income countries, access to SRH education remains limited (5). Barriers such as limited access to formal education, restricted internet connectivity, and cultural or societal resistance to open discussion of sexuality and reproductive rights continue to shape young people\u0026rsquo;s exposure to reliable information (6\u0026ndash;8). Although several studies from sub-Saharan Africa, including Angola, have reported moderate to good overall levels of SRH knowledge among adolescents and young adults, this knowledge is not evenly distributed \u0026nbsp;\u003cspan lang=\"EN-US\"\u003e(9\u0026ndash;11).\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003ePersistent disparities according to education level, place of residence, and access to information remain evident\u0026nbsp;(12,13).\u0026nbsp;and adequate knowledge alone may be insufficient to prevent adverse SRH outcomes in settings with limited access to services and preventive interventions.\u003c/p\u003e\n\u003cp\u003eAngola, a country in southwestern Africa, continues to face significant SRH challenges among its youth population. National estimates indicate that approximately 26\u0026ndash;30% of girls aged 15\u0026ndash;19 years have already begun childbearing, a proportion substantially higher than the sub-Saharan African average\u0026nbsp;(14,15).\u003c/p\u003e\n\u003cp\u003eGender norms, including early union formation, unequal power dynamics, and stigma surrounding contraceptive use, may further constrain young people\u0026rsquo;s autonomy and their ability to translate knowledge into effective preventive behaviours\u0026nbsp;(16\u0026ndash;18).\u003c/p\u003e\n\u003cp\u003eThe epidemiology of STIs also remains an important concern. Angola is classified as a high-endemicity country for hepatitis B virus (HBV), with national estimates ranging between 8% and 15%(19). Although HBV vaccination was introduced into the national immunization schedule in 2006, vaccination gaps, irregular early-childhood coverage, and limited screening among adolescents and young adults may contribute to ongoing transmission. Recent\u0026nbsp;evidence from sub-Saharan Africa underscores that HBV remains one of the most significant yet under-recognized infectious disease threats among youth (20,21).\u0026nbsp;However, data on HBV infection among adolescents and young adults in Angola, particularly at the subnational level, remain scarce.\u003c/p\u003e\n\u003cp\u003eIn response to these challenges, the FUTURO Project, funded by the European Union, was implemented to strengthen SRH knowledge, behaviours, and policy engagement among adolescents and young adults through a multilevel communication and education strategy in selected municipalities of Benguela Province. Two cross-sectional surveys were conducted in 2021 and 2024 as part of the project. Although the original intention was to assess changes in SRH knowledge over time, direct comparisons between the two survey rounds were not methodologically appropriate, as they were based on independent samples with substantial differences in age distribution, educational attainment, and place of residence. In addition, exploratory analyses suggested that broader contextual or structural factors were influencing SRH indicators over time. To avoid potentially misleading interpretations, data from both survey rounds were therefore pooled for analysis.\u003c/p\u003e\n\u003cp\u003eThe objective of this study was to characterise sexual and reproductive health knowledge, sexual behaviours, and sexually transmitted infection profiles among adolescents and young adults aged 15\u0026ndash;25 years in Benguela Province, Angola.\u003c/p\u003e"},{"header":"Methods","content":"\u003ch2\u003e\u003cu\u003eStudy Design and Population\u003c/u\u003e\u003c/h2\u003e\n\u003cp\u003eWe conducted a pooled cross-sectional analysis of data collected from adolescents and young adults aged 15 to 25 years. The study included participants from two urban municipalities (Benguela and Lobito) and two rural municipalities (Cubal and Caimbambo). This classification was based on the administrative designation and level of urbanization of the municipalities according to provincial territorial characteristics. Data were collected during two independent survey rounds conducted in 2021 and 2024, using the same study protocol and instruments previously published \u003cspan lang=\"EN-US\"\u003e(22)\u003c/span\u003e. Participants were recruited through community outreach activities in public spaces, youth centres and churches \u003cspan lang=\"EN-US\"\u003e(23\u0026ndash;25)\u003c/span\u003e. \u003c/p\u003e\n\n\u003ch2\u003e\u003cstrong\u003e\u003cu\u003eStudy Population\u003c/u\u003e\u003c/strong\u003e\u003c/h2\u003e\n\u003cp\u003eEligible participants were adolescents and young adults aged 15\u0026ndash;25 years residing in the selected municipalities. Exclusion criteria were: (1) refusal or inability to provide informed consent; and (2) having participated in the design or implementation of FUTURO Project activities, to avoid direct exposure bias.\u003c/p\u003e\n\u003ch2\u003e\u003cu\u003eRecruitment and Data Collection Procedures\u003c/u\u003e\u003c/h2\u003e\n\u003cp\u003ePrior to data collection, study objectives and procedures were presented to local authorities to facilitate community acceptance and mobilisation. Trained fieldworkers conducted outreach activities in public and community settings.\u003c/p\u003e\n\u003cp\u003eThe questionnaire was administered in a semi-assisted approach. A trained member of the research team explained each question to ensure comprehension. Participants then completed the questionnaire independently, with the option to request clarification if needed. No personally identifiable information was collected, and all questionnaires were completed anonymously.\u003c/p\u003e\n\u003cp\u003eTo ensure data quality, supervisors checked all completed forms daily for inconsistencies or missing responses. Double-entry verification was performed during digitalization. Data were collected and managed using the REDCap secure web platform (26).\u003c/p\u003e\n\u003ch2\u003e\u003cu\u003eStructured Questionnaire and STI Testing\u003c/u\u003e\u003c/h2\u003e\n\u003cp\u003eWe used the same structured questionnaire as in the baseline study (described elsewhere) (22). The tool consisted of 25 questions divided into four thematic sections: general sexual health knowledge, HIV, contraceptive methods and gender equity. For each section, knowledge was classified as \u0026ldquo;adequate\u0026rdquo; if at least two-thirds of the questions were answered correctly. An overall score of 17 or more correct answers (out of 25) was defined as adequate general knowledge (27) . This cut-off aligns with established practices in SRH knowledge assessments \u003cspan lang=\"EN-US\"\u003e(28,29).\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eFollowing questionnaire completion, participants were offered point-of-care testing for four STIs using validated rapid diagnostic tests: HIV (Alere Determine HIV 1/2, Abbott), hepatitis B virus (HBV) (HBsAg, Nantong diagnosis Biotechnology), hepatitis C virus (HCV) (antibodies against HCV, Nantong diagnosis Biotechnology), and syphilis (Treponema pallidum antibodies, Nantong diagnose Biotechnology). \u003c/p\u003e\n\u003cp\u003eTesting was conducted in private spaces by trained staff from the Faculty of Medicine at Katyavala Bwila University. Finger-prick blood samples were used according to manufacturer instructions. Participants with positive test results received post-test counselling and were referred to pre-identified health units for confirmatory diagnosis and follow-up care.\u003c/p\u003e\n\u003ch3\u003e\u003cu\u003eSample Size Calculation\u003c/u\u003e\u003c/h3\u003e\n\u003cp\u003eThe sample size for this study was originally determined with the aim of evaluating changes in SRH knowledge following the implementation of the FUTURO Project. The project aimed to increase SRH knowledge among adolescents and young adults in Benguela Province by 20%. Due to the lack of national data on SRH knowledge in Angola, estimates from other sub-Saharan African countries were used for reference. It was assumed that approximately 40% of the youth population would have adequate SRH knowledge at baseline. Based on this assumption, and considering a 95% confidence level (\u0026alpha; = 0.05) and 80% power, a minimum of 1.400 participants was required to detect a 20% increase in knowledge over time.\u003c/p\u003e\n\u003cp\u003eAlthough the current analysis does not seek to assess the intervention effect over time\u0026mdash;due to the demographic differences between the two independent samples\u0026mdash;the same sampling strategy was retained in the second round of data collection (2024), allowing for a consistent number of participants and proportional representation across municipalities. The sample was distributed according to the population size of each municipality using data from the 2014 Angolan census, resulting in target recruitment of approximately 605 individuals from Benguela (43.2%), 371 from Lobito (26.5%), 329 from Cubal (23.5%), and 95 from Caimbambo (6.8%).\u003c/p\u003e\n\n\u003ch2\u003e\u003cu\u003eData Analysis\u003c/u\u003e\u003c/h2\u003e\n\u003cp\u003eData were analysed with SPSS software. Descriptive statistics were calculated for all variables. Categorical variables were described using absolute frequencies and percentages, while continuous variables were summarized using either the mean and standard deviation (SD) or the median and interquartile range (IQR), depending on the distribution of the data.\u003c/p\u003e\n\u003cp\u003eDue to sociodemographic differences between the 2021 and 2024 samples, direct temporal comparisons were not conducted. Instead, data from both rounds were pooled for a global analysis of SRH knowledge, and STIs prevalence.\u003c/p\u003e\n\u003cp\u003eWe conducted bivariate and multivariate analyses to explore factors associated with adequate overall SRH knowledge. Given the clear predominance of HBV infection among all STIs detected, we focused our analysis on this outcome. Therefore, an additional set of bivariate and multivariate analyses was carried out to identify factors independently associated with HBV infection.\u003c/p\u003e\n\u003cp\u003eIndependent variables included age, sex, education level, and municipality of residence (urban vs rural). Categorical variables were compared using the Chi-square test, and continuous variables using the t-test or Mann\u0026ndash;Whitney U test, depending on distribution. Logistic regression models were used for multivariate analysis. A p-value \u0026lt; 0.05 was considered statistically significant.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e\u003cu\u003eJustification for Pooling Data\u003c/u\u003e\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThe primary objective of this study was to characterise SRH knowledge, sexual behaviours, and STIs profiles among adolescents and young adults in Benguela Province, rather than to evaluate longitudinal changes or intervention impact. In addition, substantial demographic differences were observed between the two independent survey samples, limiting the validity of direct temporal comparisons. For these reasons, data from the 2021 and 2024 surveys were pooled to increase statistical power and improve the representativeness of the overall analysis.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 2.802 individuals were included in the pooled analysis: 1.400 participants from the 2021 survey and 1.402 from 2024. Overall, 1.062 participants (37.6%) were female. The distribution by municipality was as follows: 190 (6.7%) from Caimbambo, 658 (23.3%) from Cubal, 1.213 (42.9%) from Benguela, and 741 (26.2%) from Lobito.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe mean age of participants was 19.0 (SD: 0.48) years. Regarding education level, 12 participants (0.4%) reported having no formal education, 141 (5.0%) had completed primary education, 1.095 (38.7%) secondary education, and 154 (5.4%) higher education.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cu\u003eSexual Behaviour and STIs Prevalence\u003c/u\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eA total of 1.868 participants (66.7%) reported having had previous sexual intercourse, with a mean age at first sexual encounter of 18.7 (SD: 2.4) years. Additionally, 237 individuals (8.5%) reported either having being pregnant (among females) or having caused a pregnancy (among males) before the age of 19.\u003c/p\u003e\n\u003cp\u003eRegarding STIs, serological testing revealed that 33 participants (1.2%) were positive for HIV, 979 (34.9%) tested positive for HBsAg, 15 (0.5%) for HCV, and 27 (1.0%) for syphilis.\u003c/p\u003e\n\u003cp\u003eWhen analysing factors associated with adequate SRH knowledge, we found that older age (OR 1.19 95%CI 1.07-1.17, p \u0026lt; 0.001), higher education level (OR14.11 (95%CI 3.58-55.59), p\u0026lt; 0.001), and living in an urban area (OR 5.51, 95%CI 4.17-7.26, p\u0026lt;0.001) were significantly associated with adequate overall knowledge. This information is summarized in Table 1.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWhen analysing variables associated with HBV infection, we found that infection was significantly more frequent among males (OR 1.37, 95% CI: 1.14\u0026ndash;1.65; p = 0.001), participants living in Cubal (OR 1.69, 95% CI: 1.30\u0026ndash;2.18; p \u0026lt; 0.001) or Benguela (OR 2.11, 95% CI: 1.69\u0026ndash;2.65; p \u0026lt; 0.001), compared to those residing in Lobito. Additionally, HBV infection was more common among individuals surveyed in 2024 compared to those surveyed in 2021 (OR 8.77, 95% CI: 7.15\u0026ndash;10.50; p \u0026lt; 0.001). Table 2 summarizes the factors independently associated with HBV infection.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this large population-based study of over 2,800 adolescents and young adults from Benguela Province, Angola, overall sexual and reproductive health (SRH) knowledge was higher among older individuals, those with higher educational attainment, and those living in urban settings. Notably, we identified an alarmingly high prevalence of HBsAg positivity in this population.\u003c/p\u003e\n\u003cp\u003eThe observed associations between SRH knowledge and age, education level, and urban residence are consistent with previous studies from sub-Saharan Africa, which have shown that access to formal education, digital literacy, and proximity to health and information services strongly influence SRH knowledge and awareness (27) Urban adolescents and young adults are more likely to benefit from school-based programmes, online resources, and public health campaigns, whereas young people living in rural areas continue to face structural barriers related to limited connectivity, lower school attendance, and fewer youth-friendly services. These findings reinforce the persistence of intra-country inequalities in access to SRH information, even in settings where overall knowledge levels may be moderate to good.\u003c/p\u003e\n\u003cp\u003e\u003cspan lang=\"EN-US\"\u003eDespite the overall low prevalence of HIV, syphilis, and HCV, the proportion of participants testing positive for HBsAg was higher than expected compared with most published estimates for adolescents and young adults in sub-Saharan Africa. \u003c/span\u003e(19).\u003cspan lang=\"EN-US\"\u003e This finding \u003cstrong\u003esuggests a potentially high burden of HBV infection in the study population\u003c/strong\u003e\u003cstrong\u003e, \u003c/strong\u003ebut should be interpreted with caution.\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eAs hepatitis B testing was offered free of charge within the framework of a community-based project, participation may have been higher among individuals with perceived risk, prior exposure, or limited access to routine healthcare services (30\u0026ndash;32). Consequently, the observed HBsAg positivity may reflect a higher-risk subpopulation rather than the true prevalence of HBV infection in the general adolescent and young adult population. This self-selection could have contributed to an overestimation of HBV prevalence. This interpretation is further supported by the higher prevalence of HIV observed in the 2024 survey, suggesting the inclusion of individuals with a higher underlying risk profile.\u003c/p\u003e\n\u003cp\u003eAlthough the prevalence of HIV, syphilis, and HCV was relatively low overall, HIV prevalence was higher in the 2024 survey compared to the 2021 round. A substantial proportion of participants also tested positive for HBV, particularly among males and those residing in the municipalities of Cubal and Benguela.\u003c/p\u003e\n\n\n\u003cp\u003eHBV screening was based on a single rapid diagnostic test for HBsAg without confirmatory serological testing. Although such tests are widely used in field and resource-limited settings, false-positive results cannot be excluded. Confirmatory testing, including HBV DNA quantification or additional serological markers such as Hepatitis B core antibody (anti-HBc), was not performed; therefore, the results should be interpreted as screening-based HBsAg positivity rather than confirmed HBV infection.\u003c/p\u003e\n\u003cp\u003eThe higher HBsAg positivity observed in 2024 compared to 2021 may partly reflect differences in the composition of the study population. Notably, the higher HIV prevalence in 2024 (measured using a widely validated and WHO-recommended assay) suggests a shift toward a higher-risk sample. This potential selection bias toward more vulnerable individuals may have contributed to the increased HBsAg positivity.\u003c/p\u003e\n\u003cp\u003eSeveral factors may contribute to the substantial burden of HBV infection detected in this study. First, gaps in hepatitis B vaccination coverage may play an important role. Although the HBV vaccine was introduced into the Angolan national immunization schedule in 2006, adolescents and young adults included in this study may not have fully benefited from routine infant vaccination, particularly those born during the early years of vaccine rollout or residing in rural or underserved areas \u003cspan lang=\"EN-US\"\u003e(21)\u003c/span\u003e. Second, vertical and early horizontal childhood transmisi\u0026oacute;n, common in high-endemicity settings as Angola, result in chronic infection persisting into adolescence and young adulthood \u003cspan lang=\"EN-US\"\u003e(33\u0026ndash;35)\u003c/span\u003e. Limited access to routine screening and healthcare services may further contribute to a high proportion of undiagnosed infections \u003cspan lang=\"EN-US\"\u003e(36,37).\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eThe higher prevalence of HBsAg positivity observed among males may reflect gender-specific differences in exposure risks, healthcare-seeking behaviour, or engagement with preventive services. Similarly, the geographic differences observed across municipalities suggest that local contextual factors, such as access to health services, vaccination coverage, or socio-economic conditions, may influence HBV transmission and detection \u003cspan lang=\"EN-US\"\u003e(38).\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eAlthough participants surveyed in 2024 were more likely to test positive for HBsAg than those surveyed in 2021, this association should not be interpreted as evidence of a true temporal increase in HBV prevalence. The two survey rounds were based on independent samples with substantial differences in age distribution, educational attainment, and place of residence. Moreover, exploratory analyses indicated that several SRH indicators worsened over time even in municipalities where no intervention activities were implemented. These patterns suggest that broader contextual or structural factors, rather than the intervention itself, were likely influencing observed differences between survey rounds. Consequently, conducting a direct pre\u0026ndash;post comparison or attributing changes over time to the FUTURO Project would not have been methodologically appropriate.\u003c/p\u003e\n\u003cp\u003eDespite these limitations, the findings highlight a potentially under-recognised burden of HBV infection among adolescents and young adults in Benguela Province. Even under conservative assumptions, the results underscore the need to strengthen HBV prevention and control strategies in this population. Targeted catch-up vaccination campaigns for adolescents and young adults, particularly in high-prevalence municipalities such as Cubal and Benguela, should be considered. In addition, integrating HBV screening and counselling into youth-friendly sexual and reproductive health services may facilitate earlier diagnosis and linkage to care.\u003c/p\u003e\n\u003cp\u003eFinally, although overall SRH knowledge was not low, persistent inequalities by education level and place of residence highlight the need for continued investment in equitable, community-based education strategies. Improving access to accurate SRH information, alongside strengthening vaccination, screening, and youth-friendly health services, will be essential to reduce preventable SRH risks and address the long-term burden of HBV infection among young people in Angola.\u003c/p\u003e\n\n\u003ch2\u003e\u003cstrong\u003eStrengths and Limitations\u003c/strong\u003e\u003c/h2\u003e\n\u003cp\u003eThis study has several strengths. First, it includes a large sample of adolescents and young adults (over 2,800 participants), making it one of the largest population-based analyses of SRH knowledge and STI prevalence conducted in Angola to date. Second, data were collected using a standardized methodology and an identical survey instrument in both rounds, enabling comparability and enhancing internal consistency. Third, the inclusion of point-of-care testing for four major STIs adds objective biological measures that complement self-reported behaviours, which are often affected by social desirability bias. Finally, the study covers both urban and rural municipalities, allowing for meaningful identification of intra-provincial disparities.\u003c/p\u003e\n\u003cp\u003eHowever, several limitations should be acknowledged. The cross-sectional design prevents establishing causal relationships. In addition, the two survey rounds were based on independent samples with different sociodemographic characteristics, limiting their suitability for pre\u0026ndash;post or impact evaluation. For this reason, the study was not designed to assess temporal changes or intervention effects. Sexual behaviour data were self-reported and may be affected by recall or social desirability bias. Recruitment through community-based outreach represents a form of convenience sampling and may limit representativeness, although the large sample size and broad geographic coverage partially mitigate this concern. In addition, the provision of free point-of-care STIs testing may have preferentially attracted individuals with perceived risk of infection, potentially leading to an overestimation of prevalence, particularly for HBV. Finally, although validated rapid diagnostic tests were used for STIs screening, confirmatory laboratory testing was not conducted, which may have resulted in some degree of misclassification, especially for HBV infection.\u003c/p\u003e\n"},{"header":"Conclusion","content":"\u003cp\u003eThis study provides a comprehensive overview of SRH knowledge, sexual behaviours, and STI prevalence among adolescents and young adults in Benguela Province, Angola. SRH knowledge was generally higher among older, more educated, and urban youth, reflecting persistent inequalities affecting rural and lower-education populations. The exceptionally high prevalence of HBV infection underscores the urgent need for targeted HBV prevention, catch-up vaccination, and expanded screening strategies for young people.\u003c/p\u003e\n\u003cp\u003eWhile the prevalence of HIV, syphilis, and HCV was low overall, HIV prevalence was higher in the 2024 survey compared to the 2021 round, suggesting potential differences in the underlying risk profile of the study population. In addition, a notable proportion of participants tested positive for HBsAg. Although these findings suggest a potentially important burden of HBV infection among adolescents and young adults, they should be interpreted with caution, as results reflect screening-based HBsAg positivity and may be influenced by selection bias and the absence of confirmatory testing.\u003c/p\u003e\n\u003cp\u003eThese results underscore the need to strengthen HBV prevention and control strategies targeting young people, including catch-up vaccination, expanded screening, and integration of HBV services into youth-friendly sexual and reproductive health programmes. Improving equitable access to SRH information and services, particularly for rural and lower-education populations, should remain a public health priority. Further research using confirmatory testing and longitudinal designs is needed to better characterise HBV epidemiology and inform effective prevention strategies in Angola.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank all adolescents and young adults who participated in the surveys, as well as community leaders and municipal health authorities in Benguela Province for their support. We acknowledge the fieldworkers and laboratory technicians from the Faculty of Medicine at Katyavala Bwila University for their crucial role in data collection and STI testing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no competing interests to declare that are relevant to the content of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Trial\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eClinical trial number: not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted as part of the FUTURO Project, funded by the European Union. The funder had no role in the design, data collection, analysis, interpretation, or decision to submit the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was designed, implemented, and reported in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice guidelines. The study protocol was reviewed and approved by the Ethics Committee of the Ministry of Health of the Republic of Angola (MINSA) (approval number: n\u0026ordm;14/2021).\u003c/p\u003e\n\u003cp\u003eParticipation was voluntary. Written informed consent was obtained from all participants aged 18 years or older. For participants younger than 18 years, written informed consent was obtained from parents or legal guardians, and assent was obtained from the adolescents when appropriate according to their age and level of understanding. No personally identifiable information was collected, and all data were handled anonymously and confidentially.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSources of funding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStudy funded by the European Union (EuropeAid/162494/DD/ACT).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRaw data were generated at Hospital Vall d\u0026rsquo;Hebron. Derived data supporting the findings of this study are available from the corresponding author [E.E] on request\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eImplications for Policy and Practice\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe findings from this study have several important implications for public health policy and clinical practice in Angola. The exceptionally high prevalence of hepatitis B virus (HBV) among adolescents and young adults highlights the need to strengthen national vaccination strategies through catch-up vaccination campaigns targeting those who may not have benefited from routine infant immunisation, especially in high-prevalence municipalities such as Cubal and Benguela.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIntegrating HBV screening and counselling into youth-friendly health services is essential to facilitate early diagnosis and linkage to care. Addressing persistent inequalities in sexual and reproductive health (SRH) knowledge will require expanding community-based education programmes and improving access to accurate information through schools, community networks, and digital platforms where possible.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEnsuring confidentiality and reducing stigma in health facilities may improve adolescents\u0026rsquo; willingness to seek SRH care, including HBV testing and counselling. Promoting the engagement of young men is also crucial, given their higher HBV prevalence and lower health-seeking behaviour.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFinally, strengthening STI surveillance systems, including routine monitoring of HBV, HIV, syphilis, and hepatitis C, will support more effective resource allocation and evaluation of public health interventions over time. Together, these actions could contribute to more equitable and effective SRH programmes and support Angola\u0026rsquo;s broader efforts to improve adolescent and youth health outcomes.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eWondimagegne YA, Anbese AT. Risky sexual behaviors and associated factors among adolescent in Gedeo Zone, South Ethiopia: a community based cross-sectional study. Sci Rep. 2024 Aug 28;14(1):19908. \u003c/li\u003e\n\u003cli\u003eArduzzi FM, Petrin H, Castillo R. Community Nursing and Education: Strategies for Promoting Adolescent Health. SCT Proceedings in Interdisciplinary Insights and Innovations. 2025 Jan 1;3:478. \u003c/li\u003e\n\u003cli\u003eReis LF, Surkan PJ, Atkins K, Garcia-Cerde R, Sanchez ZM. Risk Factors for Early Sexual Intercourse in Adolescence: A Systematic Review of Cohort Studies. Child Psychiatry Hum Dev. 2024 Dec 25;55(6):1677\u0026ndash;90. \u003c/li\u003e\n\u003cli\u003eChandra-Mouli V, Lane C, Wong S. 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Reprod Health. 2021 Dec 16;18(1):9. \u003c/li\u003e\n\u003cli\u003eNinsiima LR, Chiumia IK, Ndejjo R. Factors influencing access to and utilisation of youth-friendly sexual and reproductive health services in sub-Saharan Africa: a systematic review. Reprod Health. 2021 Dec 27;18(1):135. \u003c/li\u003e\n\u003cli\u003eFinlay JE, Assefa N, Mwanyika‐Sando M, Dessie Y, Harling G, Njau T, et al. Sexual and reproductive health knowledge among adolescents in eight sites across sub‐Saharan Africa. Tropical Medicine \u0026amp; International Health. 2020 Jan 8;25(1):44\u0026ndash;53. \u003c/li\u003e\n\u003cli\u003eKemigisha E, Bruce K, Nyakato VN, Ruzaaza GN, Ninsiima AB, Mlahagwa W, et al. Sexual health of very young adolescents in South Western Uganda: a cross-sectional assessment of sexual knowledge and behavior. Reprod Health. 2018 Dec 29;15(1):148. \u003c/li\u003e\n\u003cli\u003eAmanu A, Birhanu Z, Godesso A. 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Understanding how social norms influence access to and utilization of adolescent sexual and reproductive health services in Northern Nigeria. Frontiers in Sociology. 2023 Oct 11;8. \u003c/li\u003e\n\u003cli\u003eCoast E, Jones N, Francoise UM, Yadete W, Isimbi R, Gezahegne K, et al. Adolescent Sexual and Reproductive Health in Ethiopia and Rwanda: A Qualitative Exploration of the Role of Social Norms. Sage Open. 2019 Jan 11;9(1). \u003c/li\u003e\n\u003cli\u003eNinsiima A, Leye E, Michielsen K, Kemigisha E, Nyakato V, Coene G. \u0026ldquo;Girls Have More Challenges; They Need to Be Locked Up\u0026rdquo;: A Qualitative Study of Gender Norms and the Sexuality of Young Adolescents in Uganda. Int J Environ Res Public Health. 2018 Jan 24;15(2):193. \u003c/li\u003e\n\u003cli\u003eSchweitzer A, Horn J, Mikolajczyk RT, Krause G, Ott JJ. Estimations of worldwide prevalence of chronic hepatitis B virus infection: a systematic review of data published between 1965 and 2013. The Lancet. 2015 Oct;386(10003):1546\u0026ndash;55. \u003c/li\u003e\n\u003cli\u003eSebasti\u0026atilde;o CS, Machado MG, Vig\u0026aacute;rio J, Comandante F, Armando A, Silva MLS, et al. Trends in active hepatitis B virus infection and associated risk factors among blood donor candidates from Luanda, Angola. Sci Rep. 2025 May 12;15(1):16478. \u003c/li\u003e\n\u003cli\u003eEberwein AE, Cummings PR, Cummings D, Andre J, Jacobsen KH. Hepatitis B (HBsAg) prevalence among obstetric patients in Caluquembe, Angola, 2023\u0026ndash;2024. PLoS One. 2025 Jul 3;20(7):e0327426. \u003c/li\u003e\n\u003cli\u003eAixut S, Esteban E, Mart\u0026iacute;nez-Campreci\u0026oacute;s J, Oliveira PR, G\u0026oacute;mez-Mart\u0026iacute;nez F, Mart\u0026iacute;n-Garc\u0026iacute;a D, et al. Sexual and reproductive health knowledge and behaviors and prevalence of sexually transmitted infections among adolescents and young adults from Angola. J Public Health (Bangkok). 2025 Aug 29;47(3):e318\u0026ndash;28. \u003c/li\u003e\n\u003cli\u003eOliveira BC, Vidal C, Pichardo Y, Hahn K, Locklear C, Moore JJ, et al. 0621 Overcoming Obstacles to Recruitment and Community Engagement During COVID-19 and Development of a Digital Community Outreach program. Sleep. 2022 May 25;45(Supplement_1):A272\u0026ndash;A272. \u003c/li\u003e\n\u003cli\u003eReck A, Holley L, Bower K, Whitaker S, Hall C, Brown C, et al. Building trust in rural communities: recruitment and retention strategies in developmental science. Front Public Health. 2025 May 7;13. \u003c/li\u003e\n\u003cli\u003eOgora N. Strategies for retaining church youths for evangelism activities in Suneka District, South Kenya Conference. Editon Consortium Journal of Arts, Humanities and Social Studies. 2025 May 15;7(1):1\u0026ndash;16. \u003c/li\u003e\n\u003cli\u003eHarris PA, Taylor R, Thielke R, Payne J, Gonzalez N, Conde JG. Research electronic data capture (REDCap)\u0026mdash;A metadata-driven methodology and workflow process for providing translational research informatics support. J Biomed Inform. 2009 Apr;42(2):377\u0026ndash;81. \u003c/li\u003e\n\u003cli\u003eChandra-Mouli V LCWS. What does not work in adolescent sexual and reproductive health: a review of evidence on interventions commonly accepted as best practices. Glob Health Sci Pract. 2015;3(3):333\u0026ndash;40. \u003c/li\u003e\n\u003cli\u003eHamdanieh M, Ftouni L, Al Jardali B, Ftouni R, Rawas C, Ghotmi M, et al. Assessment of sexual and reproductive health knowledge and awareness among single unmarried women living in Lebanon: a cross-sectional study. Reprod Health. 2021 Dec 28;18(1):24. \u003c/li\u003e\n\u003cli\u003eAlkhalili M, Al-Hmaid Y, Kheirallah K, Mehaisen L. Assessment of Knowledge of Sexual Reproductive Health Among Female University Students in Jordan. Cureus. 2024 Feb 1; \u003c/li\u003e\n\u003cli\u003eDatta D, Andrade E, Gomez BN, Golub SA, Beil R, Patel V V. Sexual health survey recruitment approaches among patients in community health centers. Sex Health. 2025 Dec 23;22(6). \u003c/li\u003e\n\u003cli\u003eSimms V, Dauya E, Dziva Chikwari C, Bandason T, Kranzer K, Tembo M, et al. Uptake of community-based integrated HIV and sexual and reproductive health services for young people in Zimbabwe: the CHIEDZA study. BMC Health Serv Res. 2025 Nov 10;25(1):1459. \u003c/li\u003e\n\u003cli\u003eBusang J, Ngoma N, Zuma T, Herbst C, Okesola N, Chimbindi N, et al. Person‐centred HIV care and prevention for youth in rural South Africa: preliminary implementation findings from \u003cem\u003eThetha Nami ngithethe nawe\u003c/em\u003e stepped‐wedge trial of peer‐navigator mobilization into mobile sexual health services. J Int AIDS Soc. 2025 Sep 8;28(S5). \u003c/li\u003e\n\u003cli\u003eVeronese P, Dodi I, Esposito S, Indolfi G. Prevention of vertical transmission of hepatitis B virus infection. World J Gastroenterol. 2021 Jul 14;27(26):4182\u0026ndash;93. \u003c/li\u003e\n\u003cli\u003eAnsari A, Vincent JP, Moorhouse L, Shimakawa Y, Nayagam S. Risk of early horizontal transmission of hepatitis B virus in children of uninfected mothers in sub-Saharan Africa: a systematic review and meta-analysis. Lancet Glob Health. 2023 May;11(5):e715\u0026ndash;28. \u003c/li\u003e\n\u003cli\u003eSeremba E, Van Geertruyden JP, Ssenyonga R, Opio CK, Kaducu JM, Sempa JB, et al. Early childhood transmission of hepatitis B prior to the first hepatitis B vaccine dose is rare among babies born to HIV-infected and non-HIV infected mothers in Gulu, Uganda. Vaccine. 2017 May;35(22):2937\u0026ndash;42. \u003c/li\u003e\n\u003cli\u003eSolomon-Rakiep T, Olivier J, Amponsah-Dacosta E. Towards contextualized complex systems approaches to scaling-up hepatitis B birth-dose vaccination in the African region: a qualitative systematic review. Front Public Health. 2024 Oct 24;12. \u003c/li\u003e\n\u003cli\u003eMcNaughton AL, Louren\u0026ccedil;o J, Bester PA, Mokaya J, Lumley SF, Obolski U, et al. Hepatitis B virus seroepidemiology data for Africa: Modelling intervention strategies based on a systematic review and meta-analysis. PLoS Med. 2020 Apr 21;17(4):e1003068. \u003c/li\u003e\n\u003cli\u003ePeliganga LB, Horta MAP, Lewis-Ximenez LL. Enduring Challenges despite Progress in Preventing Mother-to-Child Transmission of Hepatitis B Virus in Angola. Pathogens. 2022 Feb 8;11(2):225. \u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables are available in the Supplementary Files section.\u003c/p\u003e\n"}],"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":"Sexual and reproductive health knowledge, Sexually transmitted infections, Adolescents and young adults","lastPublishedDoi":"10.21203/rs.3.rs-9301377/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9301377/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e\u003cbr\u003e\nSexual and reproductive health (SRH) knowledge is a key determinant of health outcomes among adolescents and young adults, particularly in low- and middle-income countries. In Angola, young people continue to face substantial SRH challenges, including early childbearing and a high burden of sexually transmitted infections (STIs), yet subnational data remain limited.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eObjective:\u003c/strong\u003e\u003cbr\u003e\nTo characterise SRH knowledge, sexual behaviours, and STI profiles among adolescents and young adults aged 15–25 years in Benguela Province, Angola.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e\u003cbr\u003e\nWe conducted a pooled cross-sectional analysis of two independent community-based surveys carried out in 2021 and 2024 in four municipalities of Benguela Province. Participants were recruited through outreach activities in public and community settings. SRH knowledge was assessed using a structured questionnaire, and point-of-care testing was offered for HIV (Alere Determine HIV1/2 antibodies, Abbott), hepatitis B surface antigen (HBsAg) (HBsAg, Nantong diagnosis Biotech-nology), hepatitis C virus (HCV), and syphilis (Treponema pallidum antibodies, Nantong Diagnos Biotechnology). Due to substantial sociodemographic differences between survey rounds, data were pooled and analysed as a single cross-sectional dataset. Multivariate logistic regression was used to identify factors associated with adequate SRH knowledge and HBsAg positivity.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e\u003cbr\u003e\nA total of 2,802 adolescents and young adults were included. Adequate SRH knowledge was significantly associated with older age, higher educational attainment, and urban residence. While the prevalence of HIV, syphilis, and HCV was low, a high proportion of participants tested positive for HBsAg. HBsAg positivity was more frequent among males and among participants residing in Cubal and Benguela municipalities.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e\u003cbr\u003e\nImportant inequalities in SRH knowledge persist among adolescents and young adults in Benguela Province, particularly affecting younger, with lower education level, and rural populations. The high proportion of HBsAg positivity highlights the need to strengthen hepatitis B prevention strategies, including catch-up vaccination, expanded screening, and integration of HBV services into youth-friendly SRH programmes. These findings underscore the importance of equitable access to SRH information and services to reduce preventable health risks among young people in Angola.\u003c/p\u003e","manuscriptTitle":"Sexual and reproductive health knowledge and hepatitis B surface antigen prevalence among adolescents and young adults in Benguela Province, Angola: a pooled cross-sectional study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-25 05:46:23","doi":"10.21203/rs.3.rs-9301377/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-04T18:50:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"313879598931755609021621285215963955869","date":"2026-05-04T17:50:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"235520046018253957800794656754988600847","date":"2026-05-01T01:52:07+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-17T10:38:46+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-09T08:10:34+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-09T02:19:39+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-09T02:19:05+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Public Health","date":"2026-04-02T09:35:45+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":"823ba80e-9da2-4199-9d15-1042b7d0054e","owner":[],"postedDate":"April 25th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-04T18:50:56+00:00","index":49,"fulltext":""},{"type":"reviewerAgreed","content":"313879598931755609021621285215963955869","date":"2026-05-04T17:50:55+00:00","index":48,"fulltext":""},{"type":"reviewerAgreed","content":"235520046018253957800794656754988600847","date":"2026-05-01T01:52:07+00:00","index":46,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-25T05:46:23+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-25 05:46:23","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9301377","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9301377","identity":"rs-9301377","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}