Disease-modifying effects of postexposure hepatitis A active immunization

Several studies have demonstrated the efficacy of hepatitis A virus (HAV) active vaccine in the prevention of secondary HAV infection when administered shortly after exposure.

We describe six new recruits with unknown HAV infection, of whom three received late postexposure prophylaxis with the active HAV vaccine and three were not vaccinated.

Results indicated that the vaccinated patients had a longer period from exposure to onset of symptoms (p < 0.05), shorter hospitalization, and lower liver enzyme levels.

It appears that late administration of the active HAV vaccine has a disease-modifying effect. These findings, combined with earlier reports, may have important implications for immunization policies.