Reactogenicity and immunogenicity of three different lots of a hepatitis A vaccine.

To study the immunogenicity and reactogenicity of an inactivated hepatitis A vaccine, 204 healthy individuals were randomized into three equal groups, each to receive a different vaccine lot. Each subject received a total of three doses, each of 720 ELISA units of hepatitis A vaccine HM175, according to a 0 and 1 month primary vaccination schedule, with a booster dose given at month 6. Side effects were low and were < 30% after the second injection. All subjects but one had antibodies to hepatitis A virus two months after the first dose of vaccine. At month 6 all vaccinees had seroconverted. There were no differences between the three vaccine lots with respect to side effects, seroconversion rates and geometric mean titre of antibodies. We conclude that the three lots of inactivated hepatitis A vaccine are safe, well tolerated and equally immunogenic.