Hepatitis A vaccines have been extensively evaluated in adults and children> 2 years of age, but there have been few studies in infants. Although hepatitis A infections are usually asymptomatic in infants, immunization of infants may be desirable. Infected infants and children are often the source of infection for adults, and about 30% of reported cases occur in persons < 14 years of age. However, preliminary studies suggest that maternal antibodies may interfere with the response. We compared 3 dosages of Merck's hepatitis A vaccine (VAQTA) to determine if higher dosages might overcome this interference. Healthy 2-month-olds were randomized to 1 of 3 groups and given 2 doses (4 months apart) of either a 13 unit (U) (n=79), 25U (n=81), or 50U(n=80) dosage of vaccine. Safety data after the 1st dose are shown:Table Vaccination was well tolerated; the highest dose did not result in increased rates of local or systemic reactions. Local reactions were generally mild and nearly all had resolved by the 2nd day after vaccination. Results of antibody data will be presented. Funded by Merck & Co.

Table 1
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