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Infants and adolescents vaccinated against hepatitis B are protected for more than 10 years after immunization, concludes a study in this weeks issue of The Lancet. The authors state that booster doses of vaccine do not seem necessary to ensure long-term protection.
Viral hepatitis B is a leading cause of acute and chronic liver disease worldwide. The World Health Organization (WHO) estimates that, globally, about 2 billion people have been infected with hepatitis B virus (HBV). More than 350 million people are chronically infected. WHO recommends that all countries should have universal infant or adolescent hepatitis B vaccination integrated into their national immunization programs by 1997. By the end of 2004, 168 countries implemented these immunization programs. However, whether vaccinated infants maintain protection or need a booster vaccination to sustain immunity has not been clear.
Alessandro Remo Zanetti, of the Institute of Virology Faculty of Medicine in Milan, Italy, and colleagues looked at whether concentrations of antibodies against hepatitis B were retained in 1,212 children and 446 Italian Air Force recruits vaccinated as infants and adolescents respectively. They found that 64 percent of children and 89 percent of the recruits retained protective concentrations of antibodies. The study shows that infant and adolescent immune systems can recall responding to hepatitis B more than 10 years after immunization.
Zanetti concludes, In light of our findings, the use of routine booster doses of hepatitis B vaccine does not seem necessary to maintain long-term protection in immuno-competent individuals vaccinated as infants and teenagers."
In an accompanying comment, Ding-Shinn Chen, of the National Taiwan University in Taiwan, states, Unless accumulating data show a significant increase of HBV infection in adolescents or adults who were vaccinated as children, a policy of booster vaccination in a population should not be recommended. We believe that this applies both to hyperendemic and lowlyendemic areas of the world.
Source: The Lancet