The project also appears to have decreased the incidence of hepatitis A among both children and adults and controlled the disease in a community with recurrent epidemics.
Francisco Averhoff, of the Centers for Disease Control and Prevention (CDC), Atlanta, and colleagues conducted a community-based demonstration project from 12 January 1995 through 31 December 2000, in Butte County, California.
Butte County had recurrent outbreaks of hepatitis A between 1985 and 1994.
The 1994 rate was highest among children younger than the age of 15 (193.0 per 100,000 population).
For the Butte County project, vaccination was offered to children aged 2 to 12, during vaccination clinics conducted at most schools in the county in 1995. This was done on two occasions, 6 to 12 months apart.
Between 1996 and 2000, vaccine was distributed to community health care clinicians who vaccinated eligible children without charge.
Vaccine was also available at health department clinics, selected childcare centers, and other sites.
During the study period, 29,789 (66.2%) of an estimated 44,982 eligible children received at least one vaccine dose; 17,681 (39.3%) received a second dose.
"The number of hepatitis A cases among the entire county population declined 93.5% during the study period, from 57 cases in 1995 to 4 in 2000.
"This is the lowest number of cases reported in the county since hepatitis A surveillance began in 1966," the authors report.
"The 2000 incidence rate of 1.9 per 100,000 population was the lowest of any county in the state.
| Number of hepatitis A cases declined 94% between 1995 and 2000.
| Journal of the American Medical Association |
"Of the 245 cases reported during the 6-year period, 40 (16.3%) occurred among children 17 years of age or younger, of which 16 (40%) occurred in 1995 and only 1 in 2000," they write.
"One of the 27 case patients eligible for vaccination had been vaccinated, having received the first dose 3 days before symptom onset."
"The estimated protective vaccine efficacy was 98%," the authors report.
No serious adverse events were reported among the vaccine recipients, supporting the safety of hepatitis A vaccination.
"This 6-year project demonstrated the feasibility and effectiveness of routine childhood hepatitis A vaccination and its impact on community-wide rates of disease," the authors assert.
"The decline appears to be sustained; only 2 cases were reported to the CDC during the first half of 2001," they report, citing unpublished CDC data.
"The Butte County experience suggests that, over time, routine vaccination of children can reduce overall disease rates in the community.
"This previews the potential impact of routine childhood hepatitis A vaccination, as recently recommended by the Advisory Committee on Immunization Practices for areas of the United States with consistently high hepatitis A infection rates," the authors conclude.