Use of hepatitis A vaccine in a community-wide outbreak of hepatitis A.

Hepatitis A outbreaks in communities are often difficult to control. From July 1994 through June 1995, 676 cases of hepatitis A were reported in Shelby County, Tennessee. With the licensure of a hepatitis A vaccine in February 1995, a new tool for outbreak control became available. During August-October 1995, a mass vaccination campaign was conducted. A total of 34,054 children received the first dose of hepatitis A vaccine. From December 1995 through December 1996, the number of hepatitis A cases reported inside the intervention area declined by 64%; outside the intervention area, the number of cases declined by 40%. The precise contribution of the vaccine campaign to the decline in the number of outbreak cases is difficult to quantify because community outbreaks often wane over time. The vaccine campaign may have hastened the decline of the number of outbreak cases. Future interventions should consider an earlier campaign with greater vaccine coverage.