In this issue of JAMA, Innis and colleagues1 describe a remarkable clinical trial of a new, formalin-inactivated hepatitis A vaccine performed among 40 119 children in Thailand. An impressive effort, this study compared the frequency of hepatitis A in children aged 1 to 16 years after two or three doses of either the hepatitis A vaccine developed by SmithKline Beecham Biologicals, Rixensart, Belgium, or a recombinant hepatitis B vaccine. The hepatitis A vaccine was found to be highly effective in preventing symptomatic illness associated with elevated serum alanine aminotransferase and positive IgM antibodies to hepatitis A virus (HAV). No serious adverse reactions were noted after administration of more than 109 000 doses. This is the second clinical trial to document efficacy of an investigational, formalin-inactivated hepatitis A vaccine; it follows the 1992 report of a similar vaccine developed by Merck Research Laboratories, West Point, Pa,
See also p 1328.
Lemon SM. Inactivated Hepatitis A Vaccines. JAMA. 1994;271(17):1363-1364. doi:10.1001/jama.1994.03510410075037