Swine influenza virus vaccination in patients with multiple sclerosis.

A double-blind, placebo-controlled study was conducted to evaluate the safety and efficacy of inactivated influenza virus vaccines in patients with multiple sclerosis. The vaccine used contained 200 chick cell-agglutinating (CCA) units of influenza A/New Jersey/76 and 200 CCA units of influenza A/Victoria/75 whole viruses (Merrell-National Laboratories, Cincinnati, Ohio). The frequency of clinical relapses of multiple sclerosis was the same in the vaccine-treated (four of 33 patients) and placebo-treated (four of 33) groups. An untreated control group had a slightly higher rate of relapses (four of 22). Toxic reactions to the vaccine were not a significant problem. The efficacy of the vaccination as measured by titers of hemagglutination-inhibiting antibody was comparable to that reported for the general population. However, patients with preexisting antibody were less responsive to the vaccine than normal controls studied previously. The patients who did not respond to the vaccine tended to be older and more disabled. There were no changes in titers of antibody to rubeola or rubella virus after vaccination or in relation to change in clinical course. It is concluded that the vaccine is safe and effective in patients with multiple sclerosis.