Killed Hepatitis A vaccine currently available in Indian market (Havrix) is not recommended for use in children below 2 years of age. However, seroepidemiological studies carried out by us have revealed that as many as 60% of children between 13-18 months are seronegative and hence are susceptible to the disease. Troisi et al.(1) have recently reported satisfactory seroconversion in infants given this vaccine at 2, 4 and 6 months or at 2, 4 and IS months of age. In light of this information, we have also re-analyzed our data on sero conversion of this vaccine in seronegative children below and above 2 years of age. Seroefficacy studies were carried out by assessing total antibodies to Hepatitis A by ELISA method, before and after each dose of vaccine. The data shows that while 100% seroconversion is achieved following 3 doses in all children, the rates of sero conversion among children below 2 years of age after 1st and 2nd dose are some- what lower (Table I). The differences are statistically not significant (p >0.05; chi square test) probably because of small numbers. Adverse reactions were mostly mild and comprised local pain and erythema and were not different between the two age groups.

 

Figures in parentheses indicate number of children tested.

While in India, we need not vaccinate infants at 2,4 or 6 months because of persistent maternal antibodies at this age, but certainly children between 13-18 months of age may benefit from this vaccination. However, more data would be needed to determine the rates of seronegativity and efficacy and safety of this vaccine at this age, before this could be recommended on a larger scale.
 

S.K. Mittal,
Alka Rastogi,
Department of Pediatrics.
Maulana Azad Medical College,
New Delhi 110 002.
India.
 

1. Troisi CL, Hollinger FB. Krause DS, Picekering LK. Immunization of seronegative infants with Hepatitis A vaccine: A comprehensive study of dosing schedules. Vaccine 1997: 15: 1613-1617.