The impact of hepatitis B vaccination program in central Vietnam; evaluation by population-based, cross-sectional seroprevalence survey of HBsAg

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Background: Vietnam is considered hyperendemic for hepatitis B and universal immunization for hepatitis B among infants has been implemented since 2003. To implement better disease control policies, effective impact evaluation of the vaccination program is warranted. Methods and materials: We conducted a stratified, multistage, cluster sampling survey of hepatitis B surface antigen (HBsAg) positivity among people aged 1–39 years old. Participants were randomly selected from the 4 provinces (Khanh Hoa, Ninh Thuan, Binh Dinh, Quang Ngai) in the central area of Vietnam via probability proportionate to size sampling. A face-to-face questionnaires and HBsAg rapid tests were administrated. Results: A total of 2078 participants were included into the study. The seroprevalence of HBsAg by age group for every 5years old was estimated as shown on the table below.Tabled 1agenHBsAg(+)95%CI1–42661.50%0.32–2.985–93663.01%1.25–4.7610–142981.01%0.00–2.1515–192493.61%1.28–5.9520–2416710.18%5.55–14.8125–292227.21%3.78–10.6430–3425211.11%7.20–15.0235–392589.30%5.73–12.87 Open table in a new tab In Vietnam, hepatitis vaccine was introduced in 1997 and was expanded nationwide in 2002. A birth dose was added to the immunization schedule in 2003. The decline in the prevalence of HBsAg in younger age groups may be attributed to the immunization program. However, the administrative birth dose coverage of Hepatitis B vaccine became temporally low after media reports of adverse events following immunization in 2007. High prevalence of HBsAg of HBsAg between the age of 5 and 9 in this area may be due to the low coverage of birth dose. Conclusion: Population based seroprevalence survey is able to provide valuable information to assess the effectiveness of previous vaccination and formulate future immunization policy. The survey with rapid field test is feasible and affordable way which can be applied in resource limited settings.