Hepatitis B Vaccine May Be Linked to MS

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Hepatitis B Vaccine May Be Linked to MS


Findings of Threefold Increased Risk Contradict Most Previous Research



By Salynn Boyles
WebMD Medical News Reviewed By Brunilda Nazario, MD
on Monday, September 13, 2004

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Sept. 13, 2004 --The hepatitis B vaccine series has been administered to
more than 20 million people in the U.S. and more than 500 million people in
the world. It is more than 95% effective in preventing an infection that
kills millions annually. However anecdotal evidence has linked the vaccine
to an increased risk for multiple sclerosis.

Now a new study in the Sept. 14 issue of the journal Neurology offers the
some of the strongest evidence supporting the link.

In the study, researchers report that vaccination with the recombinant
hepatitis B vaccine is associated with a threefold increased risk of
multiple sclerosis.

They concluded that the benefits of the vaccine still appear to outweigh
the risks, but added that the findings "challenge the idea that the
relation between hepatitis B vaccination and the risk of MS is well
understood."

"We aren't policy makers, but it is important to recognize that many lives
are saved by this vaccine," researcher Susan Jick, DSc, tells WebMD. "We
certainly aren't suggesting that people stop getting vaccinated. But this
study raises important questions."

The actual cause of MS is still unknown but MS is believed to be an
autoimmune disease in genetically susceptible persons. Reports of hepatitis
B vaccination and MS were from anecdotal case reports, not scientifically
controlled studies.

A Billion Doses

Approximately 350 million people worldwide are infected with hepatitis B
virus, and as many as 65 million will die from liver cancer or cirrhosis of
the liver as a result. The hepatitis B vaccine has generally been
considered one of the safest vaccines ever produced, and more than a
billion doses have been given since was first made available in the early
1980s.

Reports in the mid-1990s pointing to a link between the vaccine and MS lead
the French government to temporarily suspend the routine immunization of
pre-adolescents in schools, but most clinical trials have not supported the
association.

Two years ago an immunization safety committee guided by the Centers for
Disease Control and Prevention and the Institutes of Health reported that
the clinical evidence "favors rejection of a causal relationship between
hepatitis B vaccine and multiple sclerosis."

In the newly published study, researcher Miguel Hernan, MD, used a national
health database from the U.K. to identify MS patients and people who had
gotten the hepatitis B vaccine. Roughly 3 million Britons were registered
in the database, and the researchers included only 163 of more 700 cases of
MS patients and 10 times as many people who did not have MS in the analysis.

The researchers estimated that immunization was associated with a threefold
increase in MS risk within the three years following vaccination.

Most With MS Weren't Vaccinated

While conceding that the new study was well designed and well executed,
University of Washington neurology professor Anne H. Cross, MD, argues that
the exclusion of so many MS patients in the analysis could have been a
factor in the outcome. Of 713 MS cases identified, the researchers included
only 163 in their study and just 11 of these developed first symptoms of MS
within three years of vaccination.

"One must consider whether this selection process, which was deemed
necessary to properly perform the study, might have led to some
unrecognized bias," Cross wrote in an editorial she co-authored.

It makes little sense, she says, that the hepatitis B vaccine causes MS
when there is no evidence linking the virus to the disease.

"The vaccine is just a peptide (a small protein) of the virus, so it stands
to reason that if there is a link between the vaccine and MS there would
also be a link between hepatitis B virus infection and MS," she tells WebMD.

She also pointed out that more than 90% of the multiple sclerosis patients
in the database had not been vaccinated against hepatitis B.

The hepatitis B vaccine is now routinely given to infants in the U.S. as a
series of shots, and CDC spokesman Eric Mast, MD, MPH, noted that there is
no evidence linking the vaccine to MS or any other neurological disease in
children.

Mast, who is acting director of the division of viral hepatitis, tells
WebMD that even with the addition of the newest study, the clinical
evidence does not support a link between the hepatitis B vaccine and MS.

"This has certainly been on our radar screen, and we need to continue to
look at it," he says. "But the preponderance of evidence suggests no
association."

----------

SOURCES: Hernan, M. Neurology, Sept. 14, 2004; vol 63: pp 772-723. Susan
Jick, DSc, associate professor of epidemiology, Boston School of Public
Health. Anne H. Cross, MD, professor of neurology, Washington University,
St. Louis. Eric Mast, MD, MPH, acting director, division of viral
hepatitis, CDC.


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http://www.healthday.com/view.cfm?id=521178
HealthDayNews
September 13, 2004

Hepatitis Shot Tied to MS, Study Suggests
Vaccine's association could be statistical fluke, expert says

By Randy Dotinga
HealthDay Reporter


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.

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.

"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."

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.

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.

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.

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.

MS has a wide variety of symptoms, ranging from tingling, numbness, and pain
to muscle weakness, impaired balance, and mental problems.

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.

The results of the study, funded by the National Multiple Sclerosis Society,
appear in the Sept. 14 issue of Neurology.

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.

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.

It's also possible that other unknown factors could affect the development
of MS.

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.

"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."

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.

"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."