NEW YORK (Reuters Health) - Hepatitis A infections, usually transmitted
via contaminated food, can cause debilitating illness, but protection afforded
by the hepatitis A vaccine last more than a decade, a new study shows.
In fact, antibodies against hepatitis A virus persist for up to 27 years after
vaccination, report investigators from the Centers for Disease Control and
Prevention in Atlanta and the Alaska Native Tribal Health Consortium in
Anchorage.
Lead author Dr. Laura L. Hammitt, now at the Kenya Medical Research
Institute/Welcome Trust Collaboration in Kilifi, and colleagues enrolled 144
children and 128 adults who responded to a three-shot series of hepatitis A
vaccine to assess the persistence of antibodies.
The adults had received a primary dose of hepatitis A vaccine, with a second
vaccination given 1 month later and a third given 12 months after the first.
The children were between 3 and 6 years of age and were given three doses at
various intervals over the course of a year.
Hammitt's team collected blood samples 1 month after vaccination and again 1 to
10 years after vaccination to test for anti-hepatitis A antibodies. The
researchers calculated long-term antibody persistence based on the observed rate
of decline in concentrations.
"The estimated duration of antibody persistence was 21-27 years, depending on
the vaccination schedule," Hammitt and colleagues write in the Journal of
Infectious Diseases.
They say the findings show that protective levels of anti-hepatitis A antibodies
are retained for at least 10 years after vaccination. "Hepatitis A booster doses
after completion of the primary vaccination series do not appear to be warranted
and are not currently recommended," the CDC team advises.
Nonetheless, they point out, antibody concentrations do decline over time and
ongoing monitoring is needed "to assess whether persons vaccinated as children
will be protected throughout adulthood."
SOURCE: Journal of Infectious Diseases, December 15, 2008.
