In France in 1996, 200 cases of MS were reported directly following a round of Hepatitis B vaccinations. Since that point, many theories have emerged linking the Hepatitis B vaccination with the onset of Multiple Sclerosis, but the following study is the first to directly demonstrate it. The risk must be kept in context however, and the study does not show the important distinction of whether the vaccine causes MS in people who would otherwise never have developed it, or instead worsens/hastens MS in people who already had it (but did not know they did). Read on...

"Children who are vaccinated against hepatitis B appear to have a greater risk of developing multiple sclerosis, a new study suggests.

But the researchers themselves caution that there is no evidence the vaccine -- usually given to students around Grade 4 -- actually causes MS in young people who would otherwise not develop it.

"Our study cannot distinguish whether the vaccine hastens the onset of MS in persons destined to develop the disease years later, or whether it causes new cases of MS in susceptible individuals," [and furthermore]...

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Hepatitis B vaccine linked to multiple sclerosis

By ANDRÉ PICARD
PUBLIC HEALTH REPORTER
Tuesday, September 14, 2004 - Page A19

Children who are vaccinated against hepatitis B appear to have a greater risk of developing multiple sclerosis, a new study suggests.

But the researchers themselves caution that there is no evidence the vaccine -- usually given to students around Grade 4 -- actually causes MS in young people who would otherwise not develop it.

Rather, they believe that a particular component of the vaccine may hasten the development of symptoms of the neurological condition and, as such, the finding could provide important clues on the prevention and treatment of MS.

"Our study cannot distinguish whether the vaccine hastens the onset of MS in persons destined to develop the disease years later, or whether it causes new cases of MS in susceptible individuals," said Miguel Hernan of the Harvard School of Public Health in Boston and lead author of the study.

He said it is important to keep the risk in context, noting that the vast majority of people in the study who developed MS, 93 per cent, had not been vaccinated.

Dr. Hernan also stressed that the demonstrable benefits of the hepatitis B vaccine also outweigh the theoretical risks of MS.

Despite the cautions, the new research, published in today's edition of the medical journal Neurology, is likely to reignite a long-simmering debate about the link between the hepatitis B vaccine and MS.

In 1996, about 200 cases of MS and related central nervous system disorders were reported in France following a routine round of vaccination. As a result, the French government suspended routine hepatitis B immunization of preadolescents in schools.

Since then, a number of studies have probed the issue, but produced conflicting results and much debate about methodology.

More than 50,000 Canadians have multiple sclerosis. In fact, Canada has one of the highest rates of MS in the world.

In people with MS, for reasons that are unclear, the body's immune system malfunctions and starts attacking myelin, the protein coating that surrounds and protects nerve fibres. There is no single cause, but the condition has been linked to everything from lack of exposure to the sun to exposure to the common childhood infection Epstein-Barr virus.

The new study was based on information from a large database of patients in the United Kingdom. Researchers compared the records of 163 people with MS to 1,604 similar individuals without the condition. They found that within three years of receiving the hepatitis B vaccine, the risk of developing MS increased more than three-fold.

But, overall, there were only 11 new cases of MS identified in the study period.

In a commentary also published in Neurology, Robert Naismith, a professor of neurology at Washington University in St. Louis, said the new research is important because the methods used were sound but cautioned that the findings based on 11 cases of MS perhaps should not be generalized to the population at large.

Dr. Naismith also noted that the study did not examine whether the hepatitis B vaccine caused relapses or worsened the disease in people who were already suffering from MS. This, he said, could provide important clues about the potential impact of the vaccine.

Dr. Naismith said the new research should not be viewed as the final word on the issue but as "another piece in the puzzle of MS causation." He also stressed that there is "indisputable" benefit to continuing the vaccinations.

Hepatitis B is one of the most common infections, affecting more than 350 million people worldwide. The vaccine is considered to be one of the safest and most effective, preventing about 95 per cent of cases. Still, about 5,500 people die of hepatitis B in North America each year. While the virus generally has minor effects, in a small percentage of cases it can lead to liver cancer.

Original article can be found here
http://www.theglobeandmail.com/servlet/ArticleNews/TPStory/LAC/20040914/HVACCINE14/TPHealth/