- People who are vaccinated against hepatitis B are at
increased risk of multiple sclerosis, a study shows. US public health experts
found the link when they looked at data on more than 1,500 UK patients.
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- The Harvard team does not know whether the vaccine causes
MS in those prone to the disease or speeds up MS in those destined to have
it.
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- The benefits of protecting against hepatitis might outweigh
any risk, wrote the authors in Neurology.
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- In the UK, people who are at increased risk of hepatitis
B because of their lifestyle, occupation or other factors such as close
contact with a case or carrier are advised to be immunised against this
virus.
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- It is passed from person to person through blood contact.
The virus may also be present in saliva, vaginal secretions, and other
body fluids.
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- This means people at high risk include intravenous drug
misusers, individuals who change sexual partners frequently, health care
workers, prisoners and prison staff and those travelling to areas of high
prevalence such as the Far East.
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- Conflicting evidence
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- About one in four infected of those with hepatitis B
will develop a serious liver disease such as chronic hepatitis, cirrhosis
or liver cancer develops after a number of years.
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- In recent years, concerns have been raised that the vaccine
may trigger serious autoimmune diseases, especially multiple sclerosis.
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- These fears were fueled in the 1990s when about 200 people
in France developed MS shortly after receiving the hepatitis B vaccine.
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- In February 2001, the results of a long-term study of
hepatitis B vaccine and MS in nurses were published in the New England
Journal of Medicine.
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- This study, by researchers at Harvard School of Public
Health, found no link between the two.
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- However, some of the same researchers now believe there
is a link.
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- In the latest study Dr Miguel Hernan and colleagues looked
at people registered with a GP in the UK who had been diagnosed with MS
between 1993 and 2000.
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- When they looked at hepatitis B immunisation patterns
among these 163 MS patients and 1,604 'control' patients without MS from
the same GP database, they found a link between the vaccine and MS.
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- Dr Hernan said: "We estimated that immunisation
against hepatitis B was associated with a three-fold increase in the incidence
of MS within three years following vaccination."
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- He said more research would be needed to find out why
this might be.
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- Caution
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- "It is also important to stress that 93% of the
MS cases in our study had not been vaccinated," he said.
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- Thus, for some, the small risk of MS posed by immunisation
would be far outweighed by the protection against potentially fatal liver
problems, he said.
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- In an accompanying editorial, Dr Robert Naismith and
Dr Anne Cross from Washington University said: "This article should
be viewed as another piece of the puzzle of MS causation."
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- They said the findings were not strong enough to suggest
that current immunisation policy should be changed in any way.
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- A spokeswoman from the British Liver Trust said the findings
were interesting but the suggested link should be viewed with some caution.
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- "Given that many vaccinations for hepatitis B are
given in a workplace setting, it is possible that a proportion of vaccinations
do not figure in the control group's records.
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- "We don't know whether that has been taken account
of in the research.
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- "If it hasn't then the association may be much less
than the three fold increase suggested here," she said.
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- A spokesman for the Multiple Sclerosis Society said:
"We need to study these findings in the context of other recent research
which has shown no link between the vaccination and MS.
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- "Even on this evidence, however, it is obvious that
the serious risks of hepatitis B vastly outweigh any very small possible
risk from vaccination."
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- © BBC MMIV http://news.bbc.co.uk/2/hi/health/3651782.stm
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