The hypothesis that vaccines might cause MS was fueled by anecdotal reports of MS following HepB administration and two case-control studies showing an increase in the incidence of MS in vaccinated persons that was not statistically significant. However, two large case-control studies evaluated whether HepB causes MS or whether HepB, tetanus, or influenza vaccines exacerbate symptoms of MS. The first study in a cohort of nurses identified 192 women with MS and 645 matched controls. The RR of multiple sclerosis associated with exposure to HepB was 0.9 and the RR within 2 years before the onset of disease was 0.7. There also was no association between the number of doses of HepB and the risk of MS.

The second study included 643 patients in Europe with MS relapse occurring between 1993 and 1997. Exposure to vaccination in the 2-month period before relapse was compared with the four previous 2-month control periods. The RR of relapse associated with the use of any vaccine was 0.71, and with HepB, tetanus, and influenza vaccines it was 0.67, 0.75, and 1.08, respectively. In a case-control study in France, 143 cases of MS in children <16 years of age were matched to 1122 controls; 32% of cases and 32% of controls had received HepB in the 3 years before the index date.132 A subsequent study by the same group looked at first ever episodes of acute inflammatory demyelination in children, irrespective of the subsequent course of the disease. The rates of HepB vaccination in the 3 years before the index date were 24.4% for 349 cases and 27.3% for 2941 matched controls, for an adjusted OR of 0.74 (95% CI 0.54, 1.02), although a possible trend was seen for one vaccine type.

Other well-controlled studies also found that influenza vaccine did not exacerbate symptoms of MS. In a retrospective study of 180 patients with relapsing MS, infection with influenza virus was more likely than immunization with influenza vaccine to cause an exacerbation of symptoms, suggesting that influenza vaccine is actually likely to prevent exacerbations of MS.134 In a multicenter, prospective, randomized, double-blind trial of influenza vaccine among 104 patients with MS, immunization was not associated with exacerbation of symptoms or change in disease course.

—Marshall, Gary S. “Addressing Concerns About Vaccines.” The Vaccine Handbook: A Practical Guide for Clinicians. 3rd ed. New York: Professional Communications, Inc., 2010. 232. Print.

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