Decline of maternal hepatitis A antibodies during the first 2 years of life in infants born in Turkey

Selective immunization of at-risk groups may reduce the incidence of hepatitis A infection, but only the inclusion of hepatitis A vaccine in a routine universal childhood immunization schedule would guarantee control of the infection. But the interference by maternally derived hepatitis A antibodies (anti-HAV) with the immunogenicity of inactivated hepatitis A vaccine is still important in the determination of the optimal age for hepatitis A vaccination. The hepatitis A vaccines have not been assessed widely in children under the age of 2 years and are not currently licensed for this age group in many countries. A prospective trial was performed to detect seroprevalence of maternal hepatitis A antibodies during the first 2 years of life among young infants born to hepatitis A antibody positive mothers in Turkey. We measured at-birth anti-HAV in 147 infants born in our hospital and in their mothers and then from the offspring at months 3, 6, 9, 12, 15, 18, 21, and 24. The prevalence of seropositivity among the mothers at birth were found similarly high (93.9%) to the studies previously done among the adults in our area. The prevalence of anti-HAV among children aged 0, 9, 12, 15, 18, and 21 months were 93.9%, 62.6%, 36.1%, 13.6%, 6.1%, and 0.7%, respectively. Although a proportion of infants still had measurable antibodies at 9 and 12 month of age, two thirds of the infants over the age of 12 months were at high risk of acquiring hepatitis A infection, as living in a endemic region.