Immunogenicity and reactogenicity of an inactivated hepatitis A vaccine in Indian adults.

BACKGROUND: In India, a possible decrease in the prevalence of anti-HAV (hepatitis A virus) antibodies in adults has increased their susceptibility to HAV infection. We evaluated the immunogenicity and reactogenicity of an inactivated hepatitis A vaccine administered in a 3-injection protocol. METHODS: Thirty-five healthy adult volunteers, seronegative for anti-HAV IgG, were administered 720 ELISA units/ml of the inactivated hepatitis A vaccine intramuscularly at days 0, 30 and 180. Anti-HAV IgG was determined at days 30, 60, 90 and 180 to assess the efficacy of the vaccine and adverse reactions were noted to evaluate its reactogenicity. RESULTS: The mean (SD) age of the volunteers was 33.1 (12.3) years and the man:woman ratio was 19:16. An overall seroprotection of 37.2% (13/35) was obtained at day 30, 57.1% (20/35) at day 60 and 85.7% (30/35) at day 90. By day 180, all the vaccinees (35/35; 100%) achieved protective seroconversion. The vaccine in general was well tolerated and no serious side-effects were observed. Only 8.6% (3/35) of subjects developed minor self-resolving adverse reactions such as local pain, erythema and/or low-grade fever. CONCLUSIONS: The inactivated hepatitis A vaccine in a three-injection protocol (0, 30 and 120 days) is safe, well tolerated and highly immunogenic in adult Indian subjects.