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Hepatitis B vaccine linked to MS

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8:01pm, September 20, 2004
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Scientists have found that people who develop multiple sclerosis (MS) are more likely than others to have received a hepatitis B vaccination in recent years. Earlier studies investigating a link between the muscle-weakening disease and the vaccine had produced predominantly negative results.

"We were very surprised" by the new finding, says study coauthor Miguel A. Hernán, an epidemiologist at the Harvard School of Public Health in Boston.

Hernán and his colleagues identified 163 MS patients in Britain who had been diagnosed with MS between 1993 and 2000. The scientists matched these patients with 1,604 people without MS who had used the same physicians' offices and were of similar age, gender, and smoking status.

The MS patients were about three times as likely to have had hepatitis B shots in the 3 years preceding onset of MS symptoms as the others were during that same period, Hernán and his coworkers report in the Sept. 14 Neurology. Among the MS patients, 6.7 percent had had a recent hepatitis B vaccination, compared with 2.4 percent among the control group.

The researchers stress that the new study does not prove that the vaccine causes MS. In fact, they note that more than 93 percent of MS patients identified in the study hadn't received hepatitis B shots at all. Nevertheless, the findings suggest a need for scientists to analyze the vaccine's components closely and to confirm the new results, Hernán says. "The last thing we want to do is destroy the reputation of a vaccine that has proved to be very effective and very safe," he says.

Hepatitis B infects 350 million people worldwide and can lead to liver cancer or cirrhosis; MS affects about 2.5 million people.

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