ATLANTA — All children should receive hepatitis A vaccine beginning at age 12–23 months, and the vaccine should be integrated into the routine childhood immunization schedule, the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices voted at its fall meeting.
In voting for inclusion in the routine childhood immunization schedule, the committee specified that all children in a single age cohort should be given the vaccine, and that those who are not vaccinated at 1–2 years can be vaccinated at subsequent visits during the preschool years.
ACIP's recommendation for nationwide use of the hepatitis A vaccine—which does not become official until approved and published by the CDC—reflects both the success of the vaccine and the limitations of current practice.
When it was licensed in 1995, the vaccine initially was recommended for use in areas with high rates of hepatitis A. Currently, it is being routinely given to children in 17 states, according to Beth Bell, M.D., of the CDC's division of viral hepatitis.
Overall rates of hepatitis A have been falling, primarily because of a precipitous decline in areas where the vaccine has been used. “The overall rate of 1.9 cases per 100,000 is certainly the lowest rate since we've been measuring,” she said.
But this policy of selective vaccination of children is no longer sustainable because, in an epidemiologic reversal, the highest rates of hepatitis A are now being seen in what were formerly considered low-incidence communities, according to committee member Tracy Lieu, M.D., of Harvard Pilgrim Health Care and Harvard Medical School, Boston.
“Our recommendation for vaccination in high-incidence states was an interim step, and our intention has always been to implement hepatitis A vaccination nationwide,” Dr. Lieu said.
Aside from the geographic shift in incidence rates, reasons why selective vaccinations can no longer be considered sustainable are that racial disparities exist and that without universal vaccination, models predict that the incidence of hepatitis A will once again increase. The highest rates now are among Hispanic children in areas not using the vaccine, Dr. Lieu said.
Recent approval of the vaccine for use among 1-year-olds provides a further impetus for change.
Currently, 5,000–7,000 cases of symptomatic hepatitis A cases are reported each year, and an estimated 20,000–30,000 cases occur nationwide.
Usage of the vaccine today prevents 81,000 cases annually. Nationwide use with vaccination at 1 year would prevent 180,000 cases of disease, according to Dr. Lieu. And while the $22 million annual direct costs of vaccination under the status quo would increase to $134 million, the cost-effectiveness ratio is still “very reasonable,” she said.
An additional question on epidemiology was raised by Jonathan Temte, M.D., who is liaison to ACIP from the American Academy of Family Physicians. “How many of the adult cases are due to transmission from children?”
“We have indirect evidence that a lot of adult cases are due to transmission from children,” said the CDC's Dr. Bell.
Those areas of the country where children have been immunized have seen enormous declines in cases among adults as well, Dr. Bell said. “And a large part of what I think of as a child-driven disease that affected both children and adults in communitywide outbreaks we don't see in that part of the country any more. There's little reason not to assume that we would see similar benefits by herd immunity in unvaccinated areas of the country.”
Two vaccines now are approved for use in children 1 year and older, Havrix (GlaxoSmithKline) and Vaqta (Merck). A minimum interval of 6 months between doses is recommended.