Children vaccinated against the hepatitis A virus before age 2 remain protected for at least a decade, according to new research that supports current federal guidelines that all children receive the shot.
The findings – published in Hepatology, a journal of the American Association for the Study of Liver Diseases – are the first to indicate the long-term effectiveness of the hep A vaccine.
"Our study demonstrates that [protection against] hepatitis A persists for at least 10 years after primary vaccination with two-dose inactivated HAV vaccine when administered to children at ages 12 months and older," said lead researcher Dr. Umid Sharapov, an epidemiologist with the Centers for Disease Control and Prevention.
"These findings support current [CDC] guidelines for routine administration of two doses of inactivated hepatitis A vaccine to all children in the U.S. beginning at the age of 12 months."
The researcher noted a future booster dose may be necessary to maintain protection against hep A.
The World Health Organization estimates that 1.4 million cases of hep A occur worldwide each year. The disease affects the liver; ingestion of contaminated food or water can transmit the virus.
In the U.S., hep A cases have decreased by 90 percent in the past 20 years, due to the routine vaccination of children 12 to 18 months, according to the CDC. About 20,000 new cases are reported each year, the agency said.
For the new study, researchers tracked the effectiveness of the vaccine in nearly 200 healthy infants who were monitored for 10 years after the second dose of vaccine. One month after vaccination, children showed signs of protection from the virus. At the ten-year follow-up most children retained that protection.