SEROEPIDEMIOLOGY OF HEPATITIS-A IN BLACK SOUTH-AFRICAN CHILDREN

A community-based sero-epidemiological survey was undertaken to determ ine the age-specific prevalence rates of hepatitis A virus (HAV) infec tion in a representative sample of 782 urban black children aged from newborn to 13 years. Among children aged 0 - 5 months, the prevalence of anti-HAV was 68,8% (95% confidence interval (CI) 60,6 - 77,0%); thi s fell to a low of 2,5% (CI 0,1 - 4,9%) in those aged 6 - 11 months, i mplying the presence of maternal antibody in the first few months of l ife. By the age of 2 years, 51,2% (CI 45,7 - 56,7%) had anti-HAV, by a ge 4 the prevalence had risen to 81,4% (CI 75,5 - 87,3%) and by age 6, the prevalence of anti-HAV was almost 100% (CI 90,5 - 96,7%), reflect ing the poor socio-economic and environmental conditions these childre n live in. The lowest prevalence of HAV infection among urban black So uth African children was during infancy, before the age at which the i ncidence rate rose sharply; e.g. 1 out of 5 children was already infec ted with HAV by its 2nd birthday. Vaccination in infancy will therefor e have the biggest impact on the spread of HAV. However, before HAV va ccination in infancy is advocated, vaccine immunogenicity in infancy a nd the possible detrimental effect of maternal antibodies on the immun ogenicity of the vaccine need clarification.