Routine vaccination of children reduces incidence of hepatitis A
- Diel, Roland MD, MPH
BACKGROUND
Most cases of hepatitis A occur in community-wide outbreaks. Hepatitis A vaccine prevents disease. The effect of routine childhood vaccination in communities with recurrent epidemics remains unclear.
OBJECTIVE
To examine the effect of routine childhood vaccination against hepatitis A in a community with recurring epidemics.
SETTING
Butte County, California; 1995 to 2000.
METHOD
Observational study.
PARTICIPANTS
29,789 children aged 2 to 12 years.
INTERVENTION
Inactivated hepatitis A vaccine was provided free as paediatric formulation (25 U in 0.5 mL). A second dose was given 6 to 12 months after the initial dose. Vaccination sites included schools, Health Department vaccination clinics, community health practices, childcare centres and clinics for women, infants and children.
OUTCOMES
Age-specific incidence of hepatitis A per 100,000 people; adverse reactions to vaccine. Hepatitis A was defined by serological test or clinical diagnosis.
MAIN RESULTS
Two-thirds of eligible children received at least one vaccine dose; 39.3% received two doses. Prior to the vaccination programme, the average annual incidence of hepatitis A was 47.9 per 100,000 people in Butte County. Between 1995 and 2000, age-specific incidence decreased in all groups (Table 1). The greatest reduction was in the 0 to 17 age group (from 67.3 to 13.5 per 100,000 people). The estimated efficacy of one or more vaccine doses was 98% (95% CI 86% to 100%). No serious adverse reactions were reported.
AUTHORS' CONCLUSIONS
Routine vaccination of children reduces the incidence of hepatitis A in a community with recurring epidemics.
NOTES
The main outcome was symptomatic hepatitis A, not asymptomatic infection.