Universal vaccination and hepatitis B virus infection among children in capital city Ulaanbaatar, Mongolia

Background: Mongolia has one of the highest rates of hepatitis B virus (HBV) infection in the world. Universal vaccination against hepatitis B was introduced in 1991. The aim of this study was to determine the prevalence of chronic HBV infection among children in capital city Ulaanbaatar in order to determine the effectiveness of vaccination program. Methods: A nationwide cross-sectional survey was carried out in four main regions and metropolitan area of Mongolia, through multistage, stratified, random, cluster sampling. In this abstract we present the data from capital city Ulaanbaatar. A qualitative rapid test for HBsAg/Abbott DetermineTM, Japan/ was used to determine the presence of HBsAg. Results: A total of 1983 children were enrolled in this survey 968 (48.8%) of whom were girls. Age of study population ranged from 4 to 6 years (meanąSD:5.0ą0.8). Around 90% of children were attending kindergarden and schools. Prevalence of HBsAg positivity was 0.3% (n=6) without difference by sex. HBsAg positivity rate was 0.1%, 0.4% and 0.3% among 4, 5 and 6 year old children (p=0.808), respectively. All children were vaccinated at hospital and none of them received hepatitis B vaccine at home. Mother's HBsAg positivity status was not significantly different among HBsAg positive and negative children (0.4% vs. 0.3%). Conclusion: Prevalence of HBsAg among children is much lower compared to the previous study results suggesting a good vaccination program against hepatitis B in Ulaanbaatar city.