- (HealthDayNews) - Fueling the continuing debate over
the safety of the popular hepatitis B vaccine, a new study suggests that
it contributes to a tiny increase in the number of multiple sclerosis cases.
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- But a neurologist said the results may be a "statistical
fluke," and the study authors don't tell adults or children to stop
taking the vaccine, which prevents a potentially deadly type of liver disease.
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- "If you're in a population that is in any way at
increased risk for hepatitis B, you should get the vaccine," said
study co-author Susan Jick, an associate professor of epidemiology at Boston
University. "The risk of getting hepatitis B and dying from it is
much higher than the risk of getting MS."
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- Hepatitis B, spread through blood and body fluids, can
lead to cirrhosis -- scarring of the liver -- and liver cancer. An estimated
1.25 million Americans are infected, and about 5,000 die of the chronic
form of the disease each year.
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- High-risk groups face transmission through sex or infected
needles. They include drug users, people already infected with sexually
transmitted diseases, gay men, AIDS patients, and health-care workers.
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- While the hepatitis B vaccine is considered to be 95
percent effective and is routinely recommended for children and adolescents,
it's been dogged by questions about its safety. In 1996, an outbreak of
200 cases of MS and similar diseases in France convinced French officials
to stop vaccinating children.
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- An estimated 250,000 to 350,000 Americans, mostly women,
have MS, not to be confused with muscular dystrophy. The disease appears
to be triggered by a malfunction of the immune system that causes it to
attack the central nervous system.
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- MS has a wide variety of symptoms, ranging from tingling,
numbness, and pain to muscle weakness, impaired balance, and mental problems.
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- In the new study, researchers examined statistics in
a database that has tracked the health of about 3 million residents of
Great Britain since 1987. They looked for patients who were first diagnosed
with MS between January 1993 and December 2000 and then checked their immunization
records.
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- The results of the study, funded by the National Multiple
Sclerosis Society, appear in the Sept. 14 issue of Neurology.
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- Researchers found the risk of MS grew by three times
over the three years after hepatitis B vaccination. On the other hand,
93 percent of those who developed MS had never been vaccinated for hepatitis
B. The study didn't calculate the risk of MS among all people who are vaccinated.
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- Researchers said they don't know whether the vaccine
caused MS or made it appear earlier than it would have otherwise, and Jick
declined to speculate on why a vaccine that prevents liver disease may
contribute to a nerve disease. There is speculation, however, that the
immune system plays a role.
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- It's also possible that other unknown factors could affect
the development of MS.
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- The study didn't definitively connect the vaccine to
the disease, but instead only suggested there's a link. And even that link
may not actually exist, said Dr. Anne Cross, a neurologist at Washington
University in St. Louis who co-wrote an accompanying commentary on the
new study.
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- "This study contradicts several other large studies
that did not show an increased risk of MS following the hep B vaccine,"
she said, "thus raising a question as to whether the results represent
a real finding or a statistical fluke."
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- Should Americans consider curtailing their use of the
vaccine, which is routinely given to several groups, including children
and gay men? Jick said there's no reason for panic.
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- "It is important to keep in mind that hepatitis
B is a serious disease. It's much more common than MS," she said.
"It's always important to take into account the risks and benefits."
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- More Information
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- The U.S. Centers for Disease Control and Prevention has
more on the hepatitis B vaccine (<http://www.cdc.gov>www.cdc.gov).
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- http://www.healthcentral.com/news/NewsFullText.cfm?id=521178
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