A MULTICENTER, RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL OF INFLUENZA IMMUNIZATION IN MULTIPLE-SCLEROSIS

We determined the effect of influenza vaccine in patients with relapsi ng/remitting MS. Considerable controversy sc-rounds the question of wh ether to administer influenza vaccines to MS patients. Prevention of a febrile viral illness is clearly desirable in MS, and previous studie s suggest that immunization is safe. Despite this, many clinicians avo id vaccination because they fear precipitating an MS exacerbation. We conducted a multicenter, prospective, randomized, double-blind trial o f influenza immunization in patients with relapsing/remitting MS. In t he autumn of 1993, 104 patients at five MS centers received either sta ndard influenza vaccine or placebo. Patients were followed for 6 month s for evaluation of neurologic status and the occurrence of influenza. Influenza was operationally defined as fever greater than or equal to 38 degrees C in the presence of coryza, cough, or sore throat at a ti me when the disease was present in the community. Attacks were defined in the standard manner, requiring objective change in the examination . Patients were examined at 4 weeks and 6 months after inoculation and were contacted by telephone at 1 week and 3 months. They were also ex amined at times of possible attacks but not when they were sick with f lu-like illness. Three vaccine patients and two placebo patients exper ienced attacks within 28 days of vaccine (no significant difference). Exacerbation rates in the first month for both groups were equal to or less than expected from published series. The two groups showed no di fference in attack rate or disease progression over 6 months. Influenz a immunization in MS patients is neither associated with an increased exacerbation rate in the postvaccination period nor a change in diseas e course over the subsequent 6 months.