randomized, double blind trial investigated the efficacy of a single
dose of virosome hepatitis A vaccine in 274 children, aged 18 months
to 6 years, in Leon, Nicaragua. 239 of the 274 children were included
in the primary efficacy analysis; 272 were included in the intent to
A IgM was measured every 3 months during the 18 month long study, in
order to investigate the presence of asymptomatic disease. Hepatitis
A virus RNA PCR was performed on stool samples collected every 4 weeks
throughout the study to search for asymptomatic viral shedding. Examinations
by trained nurses looked for clinically overt hepatitis every 2 weeks
throughout the study. Suspected clinically overt hepatitis was confirmed
by ALT measurement and physician exam.
of virosome hepatitis A vaccine was 100% after week 6 of the study.
Number needed to treat to prevent one case of hepatitis A in this population
this study was sponsored by the drug company that manufactures the vaccine
studied, it was valid in that the study was blinded, the groups were
very similar, and the outcomes measured were important and appropriate.