Exposure of Indian children to hepatitis A virus & vaccination age

It is known that 90 per cent of children in India are exposed to hepatitis A virus (HAV) by the age of six years. The aim of the study was to determin e when in early childhood maximum HAV infections take place and to deduce a n appropriate age for vaccination against HAV. Blood samples of 499 childre n between the ages of three days and six years were collected and tested fo r the presence of antibodies against hepatitis A. A statistically significa nt negative correlation between IgG anti-HAV and age was observed (P<0.01) up to 11.67 months when IgG anti-HAV positivity was found to be minimum (9. 25%). Subsequently a significant positive correlation was noted (P<0.01). E xposure to HAV was 28.9 per cent soon after the waning of maternal antibodi es in the 13-15 month age group which increased to 52.5 per cent by two yea rs of age and 90.9 per cent by 6 yr. It is concluded that in addition to ot her preventive measures, if children in India are to be vaccinated against hepatitis A they should be immunised against HAV by 9-10 months of age when the maternal antibodies disappear.