Inactivated hepatitis A vaccine: a safety and immunogenicity study in health professionals

The safety and immunogenicity of an inactivated hepatitis A vaccine (HM175 strain) were evaluated in 150 seronegative health professionals. The age range was 21-65 years and the mean age was 30 years. The vaccine was administered at a dose of 720 ELISA units (EU) to 73 vaccinees at 0, 1 and 6 months, and to 77 vaccinees at 0, 1 and 12 months. The seroconversion rates were 88 and 90% in the two groups, respectively, one month after the first inoculation and 99 and 100% one month after the second inoculation. The geometric mean antibody titres were similar in both groups, exceeding 3000 mIU/ml one month after the third inoculation. The vaccine was well tolerated. The most frequent side effect was transient soreness at the site of the inoculation. No serious adverse reactions were observed. The study demonstrated that the HM175 inactivated hepatitis A vaccine was safe and highly immunogenic.