Prevalence of chronic hepatitis B virus infectionbefore and after implementation of a hepatitis Bvaccination program among children in Nepal

In Nepal, it is estimated that 2-4% of the populationhas chronic hepatitis B virus (HBV). To combat thisproblem, between 2002-2004, a national three dose hepatitis B vaccination program was implemented todecrease infection rates among children. The programdoes not include a birth dose. In 2012, in order todocument the impact of the program, we conducteda sero-survey among children born before and after vaccine introduction.

In 2012, a cross-sectional nationally representativestratified cluster survey was conducted to estimatehepatitis B surface antigen (HBsAg) prevalence amongchildren born from 2006 to 2007 (post-vaccine cohort)and among children born from 2000 to 2002 (prevaccinecohort). Demographic data, as well as writtenand oral vaccination history were collected. Childrenwere tested for HBsAg, with a subset tested for totalantibody to hepatitis B core antigen. Mothers of HBsAgpositive children were tested for hepatitis B biomarkers.Furthermore, we evaluated the field sensitivity andspecificity of the SD BiolineHBsAg rapid diagnostictest.

Among 2181 post-vaccination cohort children withvaccination data by either card or recall, 87% received≥3 doses of hepatitis B vaccination. Of 1200 childrenborn in the pre-vaccination cohort, 0.28% (95%Confidence Interval [CI] 0.09-0.85%) were positive forHBsAg; of 2187 children born in the post-vaccinationcohort, 0.13% (95% CI 0.04-0.39%) were positive forHBsAg (p=0.39). Of the 6 children who tested positive for HBsAg, 2 had mothers who were positive for HBsAg.Finally, we found the SD BiolineHBsAg rapid diagnostictest to have a sensitivity and specificity of 100%.This is the first nationally representative hepatitis Bsero-survey conducted in Nepal. Overall, a low burdenof chronic hepatitis B was found in both childrenborn in the pre and post-vaccination cohort. Currentvaccination strategies should be continued.