Ethnic Differences in Immune Responses to Hepatitis B Vaccine

Abstract

A national vaccination program against hepatitis B virus (HBV) to immunize every newborn was initiated in Taiwan in 1986. A serologic survey of 1,812 fully vaccinated children residing in four aboriginal villages and four adjacent nonaboriginal Han Chinese rural villages was conducted in 1993. Children in three of the four aboriginal villages had significantly lower titers of antibody against hepatitis B surface antigen (anti-HBs) than did children in the nonaboriginal villages. Evaluation of cold chain operation for vaccine storage and transport suggested that cold chain failure was not responsible for the fact that children residing in the more remote aboriginal villages had lower mean trters of anti-HBs. However, children whose parents were both aborigines had lower anti-HBs mean trter than did children whose parents were both ethnic Han Chinese. Children of mixed parental origins had intermediate mean titer of anti-HBs. Serologic responses to Japanese encephalitis virus and diphtheria vaccines did not show such correlation with ethnic groups, indicating that the determinant for HBV hyporesponsiveness among the aboriginal children is distinct from that of other childhood vaccines. It was therefore concluded that host factors pertaining to ethnic origin might be responsible for the hyporesponsiveness to HBV vaccine in the aboriginal populations. This finding, if substantiated with further prospective studies, might provide possible means for more targeted trials to improve vaccine response and to reduce vaccine failure among these well-defined ethnic groups. Am J Epidemiol 1996;143:718-24. antibodies; diphtheria; encephalitis viruses, Japanese; ethnic groups; hepatitis B vaccines; hepatitis B virus Administration of hepatitis B virus (HBV) vaccine is the most effective means for prevention of HBV (1-3). The vaccine has repeatedly been demonstrated to be highly efficacious in inducing adequate levels of antibody against surface antigen (anti-HBs)-protective antibody, but a fraction of vaccinees mounts a poor immune response or no response at all (1, 2, 4, 5). Many factors have been shown to hinder HBV immune response, including advanced age, consumption of alcohol and nicotine (6-8), chronic diseases (9, 10), and genetic determinants These factors, except for genetic makeup, have been derived mostly