Granted partial immunity from hepatitis?

Granted partial immunity from hepatitis?

As a viral disease that attacks the liver, hepatitis B can lead to cirrhosis, liver cancer or death, and is considered a serious health care problem worldwide. There are, however, vaccines available that cause antibody formation against the hepatitis B virus in 90 to 95 percent of those vaccinated. And scientists are developing more convenient, less expensive vaccines for broader use (SN: 7/18/87, p.39). But current vaccination procedures may not be enough, according to a recent study.

Scientists at the Medical College of Wisconsin in Milwaukee and the University of Wisconsin in Madison report in the February ANNALS OF INTERNAL MEDICINE that periodic boosters of hepatitis B vaccine may be needed to maintain sufficient immunity against the virus. Mary M. Horowitz and her coauthors, after finding certain factors may influence the duration of immunity in previously vaccinated individuals, tested the efficacy of a low-dose booster vaccine in a group of hospital employees.

Of the 245 individuals studied three years after their primary vaccination, 38 percent had antibody levels so low they may no longer be protected, say the scientists. Factors directly associated with these low levels were older age, smoking and greater body weight. After receiving a single booster dose of vaccine, 78 percent of the employees with low antibody levels developed high levels within one month.

Although scientists have known that various groups respond differently to hepatitis B vaccination, the current study showed a surprisingly high percentage who either had not responded well after the first vaccination, or had lost antibodies over time. "Our study doesn't prove they aren't protected," Horowitz told SCIENCE NEWS. "But it raises some doubt as to whether they are....You could make a case for routine post-vaccination screening (based on these results)." Another study-needed to confirm that immunity actually is lost-will be difficult, she says, because a large number of vaccinated individuals would have to be followed to see whether the incidence of infection increases during the years following vaccination.

Neither the Centers for Disease Control (CDC) nor the U.S. Department of Labor's Occupational Safety and Health Administration (OSHA) considers follow-up screening necessary at this time, a CDC official said in an interview. They instead concentrate on those most likely to become infected with the virus-including drug abusers, homosexual men and health care workers.