Immunogenicity and predictors of response to a single dose trivalent seasonal influenza vaccine in multiple sclerosis patients receiving disease‐modifying therapies

AIMS: To evaluate the immunogenicity and safety of a seasonal influenza vaccine in a cohort of multiple sclerosis (MS) patients receiving different immunomodulating/immunosuppressive therapies and assess predictors of immune response. METHODS: A prospective, multicenter, non-randomized observational study including 108 patients receiving a trivalent seasonal influenza vaccination was conducted. Influenza-specific antibody titers (H1N1, H3N2, and influenza B) were measured to evaluate rates of seroprotection and seroconversion/significant titer increase. Univariable and multivariable analyses were performed to identify prognostic factors of vaccination outcomes. RESULTS: Regarding the whole cohort, seroprotection rates >70% were achieved for each influenza strain. Interferon-treated patients reached high seroprotection rates (>84%). Good seroprotection rates were seen in patients treated with glatiramer acetate. In particular for H3N2, response rates were low in natalizumab-treated patients and in the small subgroup of fingolimod-treated patients. Patients with a previous disease-modifying therapy and a longer disease duration were less likely to respond sufficiently. No severe adverse events were reported. MS disease activity was not increased after a one-year follow-up period. CONCLUSION: Vaccination led to good immunogenicity, especially in MS patients treated with interferons and glatiramer acetate. At least for the H1N1 strain, rates of seroprotection and seroconversion/significant titer increase were high (>70% and >60%, respectively) for all therapeutic subgroups. Patients with a longer duration of the disease are exposed to an increased risk of insufficient immune response to vaccination.