Epidemiology

Protection from hepatitis B vaccine lasts decades following primary immunization

Last Updated: 2009-11-02 9:00:27 -0400 (Reuters Health)

NEW YORK (Reuters Health) - In a follow-up study of Alaska Natives who received plasma-derived hepatitis B vaccine when they were more than 6 months old, a large majority were still protected 22 years later, investigators report.

Prior to licensure of hepatitis B vaccine in the U.S. in 1981, hepatitis B virus (HBV) was hyperendemic among Alaska Natives. As reported in the Journal of Infectious Diseases for November 1, the prevalence of hepatitis B surface antigen was 8.2%.

In 1981, Dr. Brian J. McMahon, from the Alaska Native Medical Center, Anchorage, and associates immunized more than 1500 Alaska Native adults and children over age 6 months with three doses of plasma-derived hepatitis B vaccine.

In 2003 the research team revisited 493 of the original subjects who had a documented response to the primary series to determine the proportion that still had antibody to hepatitis B surface antigen (anti-HBsAg) and immune memory.

Geometric mean concentration of anti-HBsAg was 21.5 mIU/mL; 60% had an anti-HBsAg level of 10 mIU/mL or higher and were thus considered to be immune.

Of the 195 persons with lower titers, 165 received a booster dose of hepatitis B vaccine (Recombivax HB). Eighty-one percent of 164 persons tested at 10 to 60 days after the booster dose had a protective anti-HBsAg level.

"Participants aged 40-59 years and those who had an (anti-HBsAg) level of 500 mIU/mL or higher after the primary series were most likely to respond to the booster dose," Dr. McMahon's team reports. Those with levels below 10 mIU/mL for more than 7 years were less likely to respond.

Overall, the researchers estimate that 92.5% of the cohort was protected. They observed no serious adverse events related to the booster dose.

"Furthermore," they add, "no participants became chronically infected, had laboratory evidence of acute hepatitis B, or had detectable HBV DNA."

They conclude, "in light of the strong evidence we present here, hepatitis B vaccine booster doses are not currently indicated."

J Infect Dis 2009;200:1390-1396.