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From Rumor to Reality: Vaccinations Not Associated with MS Onset or Relapse

Concern persists that vaccinations might trigger relapses of multiple sclerosis (MS) by inducing autoimmune responses. These fears, heightened by reports that MS developed in several French patients after hepatitis B vaccination, are now effectively contradicted by 2 carefully constructed, extensive epidemiologic investigations.

The first study, a government- and manufacturer-supported investigation performed in 6 European neurologic centers from 1992 through 1997, examined 643 patients who experienced MS relapse after at least 12 relapse-free months. Vaccine exposure during the 2 months before relapse (risk period) was compared with vaccine exposure during the preceding four 2-month periods (control periods). Ninety-six patients (15 percent) reported vaccinations during the year before relapse, 94 percent of which were confirmed using medical records: 2.3 percent of patients were vaccinated during the risk period, compared with 2.8 percent to 4.0 percent during 1 or more of the 4 control periods. Use of tetanus, hepatitis B, or influenza vaccines was not associated with increases in specific risk of relapses (relative risk, 0.22 to 1.08). Analyses of risk of relapse during 1- and 3-month risk periods found results similar to those for the 2-month risk period.

The second study evaluated use of hepatitis B vaccine and subsequent onset of MS in nurses enrolled in 2 large U.S. female Nurses' Health Study cohorts, one monitoring 121,700 nurses since 1976 and the other following 116,671 nurses since 1989. In this NIH- and manufacturer-supported study, 192 women with MS were analyzed and matched to 534 healthy controls and 111 breast cancer controls (included to address possible bias in recollections of persons with serious disease). Vaccination dates were confirmed using vaccination certificates. The relative risk for MS in nurses vaccinated at any time before onset was 0.9; for those vaccinated within 2 years of onset, it was 0.7. Analyses limited to MS patients who received the recombinant hepatitis B vaccine introduced in 1987 produced similar results. Number of vaccine doses received was not associated with risk for MS.

Comment: These 2 well-designed epidemiologic studies clearly refute concerns that vaccinations can induce relapse of MS and that hepatitis B vaccine can lead to onset of MS. The medical profession should intensify its education of an increasingly skeptical public about the important benefits and limited adverse effects of licensed vaccines, emphasizing that assessments should be based on data and not anecdotes. An editorialist states it well: "Temporal sequence does not demonstrate causality."

— N Blacklow

Published in Journal Watch Infectious Diseases February 23, 2001

Citation(s):

Confavreux C et al. Vaccinations and the risk of relapse in multiple sclerosis. N Engl J Med 2001 Feb 1 344 319-326.

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Ascherio A et al. Hepatitis B vaccination and the risk of multiple sclerosis. N Engl J Med 2001 Feb 1 344 327-332.

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• Medline abstract (Free)

Gellin BG and Schaffner W. The risk of vaccination -- The importance of "negative" studies. N Engl J Med 2001 Feb 1 344 372-373.

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• Medline abstract (Free)