Vaccinations Acquitted Of Multiple Sclerosis Link

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Vaccinations Acquitted Of Multiple Sclerosis Link

NEJM

02/01/2001

By Anne MacLennan

Vaccination does not appear to increase the short-term risk of relapse in

multiple sclerosis. Furthermore, there is no association between development of

this disease and vaccination for hepatitis B.

These are the findings of two major studies prompted by concerns that

vaccination may precipitate the onset of multiple sclerosis (MS) or lead to

relapses

and, more recently, concerns that hepatitis B vaccination may be a cause of MS

in previously health subjects.

The results of these studies should reassure recipients of the vaccines and MS

patients as well as their doctors.

The first study was for the international multi-centre Vaccines in Multiple

Sclerosis (VACCIMUS) Study group. Researchers were from the European

Database for Multiple Sclerosis Coordinating Center and the Service de

Neurologie A, Hopital Neurologique, Lyons, France; Royal Hospital

McGill

University, Montreal, Canada; and Aventis Pasteur, Lyons, France.

Objective of this study was to assess whether vaccinations increase risk of

relapse in MS.

Participants were patients included in the European Database for Multiple

Sclerosis who had a relapse between 1993 and 1997. Information on

vaccinations was obtained via a telephone interview and confirmed by medical

records.

Index relapse was the first relapse confirmed by a visit to a neurologist and

preceded by a relapse-free period of at least 12 months. Vaccination exposure

in the two-month risk period immediately before the relapse was compared with

that in the four previous two-month control periods for calculation of

relative risks.

Of 643 patients with MS relapses, 15 percent reported having been vaccinated in

the preceding 12 months. Reports of 94 percent of these vaccinations

were confirmed.

Of all the patients, 2.3 percent had been vaccinated in the preceding two-month

risk period versus from 2.l8 to 4.0 percent who were vaccinated in one

or more of the four control periods. Relative risk of relapse linked with

exposure to any vaccination in the previous two months was 0.71.

Furthermore, there was no increase in specific risk of relapse linked with

tetanus, hepatitis B or influenza vaccination. Analysis for risk periods of one

and

three months yielded similar results.

The second study -- a nested case-control study in two large cohorts of nurses

in the United States -- was by researchers at Harvard School of Public

Health, and Brigham and Women's Hospital and Harvard Medical School, in Boston,

Massachusetts, and Merck Research Laboratories, West Point,

Pennsylvania, United States.

Participants were from the Nurses' Health Study, which has followed 121,700

women since 1976, and the Nurses' Health Study II, which has followed

116,671 women since 1989. For each woman with MS, researchers selected five

healthy women and one woman with breast cancer as controls.

Multivariate relative risk of MS linked with exposure to hepatitis B vaccine at

any time before onset of the disease was 0.9. Relative risk linked with

vaccination for hepatitis B within two years before onset of the disease was

0.7.

When analyses were restricted to women with MS that began after introduction of

the recombinant hepatitis B vaccine, results were similar. Furthermore,

no association was found between the number of doses of vaccine received and MS

risk.

N Engl J Med 2001;344:319-26 ; N Engl J Med 2001;344:327-32.