A community-wide outbreak of hepatitis A in a religious community: impact of mass administration of immune globulin.

Community-wide outbreaks of hepatitis A are frequently prolonged and difficult to control. An extensive outbreak of hepatitis A in a religious community provided an opportunity to assess the effect of mass administration of immune globulin on the course of the outbreak. Between July 1, 1988 and May 30, 1989, 204 cases occurred among 3,500 residents (58/1,000), with persons aged 5-19 years having the highest attack rate. It was found that 89% of persons older than age 19, but no persons under age 20, had evidence of prior hepatitis A infection. During a 5-day campaign, immune globulin (0.02 ml/kg) was administered to 2,287 (65%) of the 3,500 residents. The cost of vaccine and syringes was less than $3,500. New cases among immune globulin recipients virtually stopped 2 weeks after the campaign, and the incidence of hepatitis in the community decreased from 9.6/week to 1.9/week. Among persons younger than age 20 years, the efficacy of immune globulin was 88.9% (95% confidence interval 77.9-94.5) for seven months. Although the authors cannot be sure that the outbreak will not recur, they believe that mass administration of immune globulin appears to have been partially effective at controlling this community-wide outbreak.