Immune response to influenza vaccine is maintained in patients with multiple sclerosis receiving interferon beta-1a.

Immunologic response was assessed prospectively using influenza vaccine in 86 patients with multiple sclerosis (MS) who were taking interferon beta-1a and 77 patients who were not taking interferon. Blood samples were assayed for hemagglutination inhibition (HI) titers 0, 21, and 28 days after immunization. The two groups were similar in the proportion of patients achieving an HI titer of 40 or greater, the prespecified primary end point and on all secondary indicators of immune response.