Study suggests hepatitis B vaccine increases risk of multiple sclerosisBMJ 2004; 329 doi: http://dx.doi.org/10.1136/bmj.329.7468.703-a (Published 23 September 2004) Cite this as: BMJ 2004;329:703
People vaccinated against hepatitis B triple their risk of developing multiple sclerosis over the following three years, a study in the current issue of the journal Neurology says (Neurology 2004;63:838-42).
Researchers led by Dr Miguel Hernán of Harvard School of Public Health analysed the United Kingdom's general practice research database, which follows a representative sample of over three million British patients.
They found 163 cases of multiple sclerosis that had first been diagnosed in the period 1993-2001 and which met the study's criteria on record keeping. Also analysed were 1604 matched controls who did not have multiple sclerosis.
The report's key finding was: “The proportion of cases that received at least one hepatitis B immunisation during the 3 years before the date of first symptoms was 6.7%, compared with 2.4% of controls. The odds ratio of MS [multiple sclerosis] for vaccination vs no vaccination was 3.1 (95% CI 1.5, 6.3).”
Several previous studies have looked for evidence of a link between hepatitis B vaccination and multiple sclerosis, but all found either no significant association or a lower odds ratio than this study. But Dr Hernán and colleagues note that most previous studies measured time from vaccination to first diagnosis of multiple sclerosis, whereas this study looked back at medical records from before each diagnosis to isolate the first onset of symptoms of the disease, usually years earlier.
The Neurology article was accompanied by an editorial by Dr Robert Naismith and Dr Anne Cross of Washington University (p 772–3) pointing out possible weaknesses in the study. Most notably, the number of subjects with both multiple sclerosis and hepatitis B vaccination was only 11.
The study's authors were careful not to take a position against immunisation, emphasising that 93% of the cases of multiple sclerosis in their study had not taken the vaccine. “Any decision concerning hepatitis B vaccination,” they concluded, “needs to take into account the large benefits derived from the prevention of a common and potentially lethal infection.”
A spokesman for the Multiple Sclerosis Society echoed the note of caution: “We need to study these findings in the context of other recent research, which has shown no link between the vaccination and MS. Even on this evidence, however, it is obvious that the serious risks of hepatitis B vastly outweigh any very small possible risk from vaccination.”
Doubts over the hepatitis B vaccine first surfaced in France in 1996, after a major national immunisation campaign, when newspapers reported about 200 cases of multiple sclerosis among vaccinated patients. Although scientific review suggested the vaccine was safe, a collapse of public confidence eventually obliged the French government to suspend routine hepatitis B vaccination of schoolchildren.
According to the World Health Organization, hepatitis B vaccine “has proved one of the safest, most immunogenic and effective vaccines,” and “should be included in routine childhood immunisation schedules for all children in all countries.”
Britain is among a small minority of countries that do not routinely immunise children against hepatitis B, although the Department of Health's Joint Committee on Vaccination and Immunisation is currently considering such a programme.