A DOSE-RESPONSE STUDY OF HEPATITIS-A VACCINE IN HEALTHY-ADULTS WHO ARE GREATER-THAN-OR-EQUAL-TO-30 YEARS OLD AND WEIGH GREATER-THAN-OR-EQUAL-TO-77 KG

The dose response relationship of 25-, 50-, and 100-U doses of an inac tivated hepatitis A vaccine was examined in 358-seronegative volunteer s in a 2-dose schedule. The 50-U and 100-U groups had statistically si gnificantly higher seroconversion rates than the 25-U group at weeks 2 , 4, 8, and 24. Seroconversion was statistically significantly greater for the 100-U compared with the 25- and 50-U doses 2 weeks after the first injection but was not significantly different by 4 weeks after t he first injection in the 50- and 100-U dose groups. After 2 injection s, all subjects in all groups seroconverted. The vaccine was well tole rated at all dosage levels.