TAIPEI: Vaccination against hepatitis B seems to protect against the virus for 25 years, suggesting that booster shots are unnecessary, according to a study from Taiwan that covered several thousand people.

Taiwan began compulsory hepatitis B virus immunization for all infants in 1984, in response to extremely high rates of infection, and the study - which appeared in the Journal of Hepatology - suggests other countries might benefit from a similar move.

"Universal vaccination in infancy provides long-term protection," wrote lead author Yen-Hsuan Ni, from the National Taiwan University in Taipei.

Hepatitis B is a viral infection that attacks the liver and is a prime cause of liver cancer. The virus is spread by contact with the blood or other bodily fluids of an infected person.

In 2009, participants in the study who were younger than age 25 were far less likely to be infected with Hepatitis B than those between the ages of 26 and 30, who were born before universal vaccination, the researchers found.

"Its efficacy in young adults is clear," Ni told Reuters health, explaining that medical experts had questions about how long the vaccine's protective effect would last. Booster shots, which are generally not recommended for Hepatitis B, were not given to subjects in the study.

For the study, which was funded by the National Taiwan University Hospital, Ni and his colleagues enrolled more than 3,300 participants under 30.

Of these, more than 2,900 - born after the mandate - received at least three doses of vaccine in their first year. Approximately 370 subject, born before 1984, were not universally vaccinated.

When they collected blood samples from January to December 2009, Ni's team found that fewer than one percent of the universally vaccinated group carried the virus and were infectious to others, compared with 10 percent of those who weren't universally vaccinated.

Fifty-six percent of those born after universal vaccination developed immunity to the disease, versus 24 percent in the group born before it began. Seven percent of the group that was universally vaccinated had an infection in their history but possibly had recovered, compared with 28 percent of the group that was not.

The World Health Organization recommends hepatitis B shots for all babies. The vaccine comes in a three-part series. AGENCIES