The hepatitis B vaccine, when administered in infancy, can last into adulthood, according to a National Taiwan University study published in Hepatology and reported by the American Council on Science and Health.
For the study, researchers followed more than 3,300 Taiwanese participants younger than 30. Over 2,900 had received the vaccine, having been born after Taiwan instituted a mandatory vaccination law in 1984. The remaining participants were unvaccinated, having been born before the mandate.
The researchers found that while 10 percent of unvaccinated participants contracted hepatitis B, only 1 percent of vaccinated participants had the virus. Of those few who contracted the virus despite being vaccinated, most got it from their mothers, either during pregnancy or around the time of delivery.
Most notably, participants ages 20 and older didn’t see any significant increase in infection rates between 1989 and 2009.
While U.S. health organizations recommend immunization at birth, it isn’t mandatory. According to statistics from the Centers for Disease Control and Prevention, more than 80,000 Americans contract hepatitis B each year—a number that could be reduced by vaccinating more people.
The Taiwan study results indicate that adult booster shots for the hepatitis B vaccine aren’t necessary for at least 25 years after the initial vaccination. Booster doses generally aren’t recommended in the United States, other than for people with compromised immune systems and those on kidney dialysis.