Flu vaccination in multiple sclerosis patients: a monocentric prospective vaccine-vigilance study

Background In 2020, the Italian Medicines Agency recommended to bring forward the flu vaccination campaign, whose importance was also emphasized for patients with Multiple Sclerosis (MS). We aimed to assess the safety profile of flu vaccines in terms of occurrence of short-term and long-term Adverse Events Following Immunization (AEFIs). Methods This is an observational study that enrolled MS patients who were eligible for any of the flu vaccines recommended by the Italian medicines Agency. Results 194 patients were enrolled. Out of 133 patients who accepted to be vaccinated, 45 experienced not serious short-term AEFIs (pain at the injection site, headache, flu-like symptoms, fatigue). Long-term AEs were detected in 12 vaccinated patients (flu-like symptoms, COVID-19 and MS relapse). No statistically significant differences in terms of infections or MS relapse were found between vaccinated and unvaccinated groups. Using Kaplan-Meier analysis we observed no differences in the cumulative survival rate in both groups. Conclusion Flu vaccines were well tolerated in MS patients, who mainly experienced not serious short term AEFIs. Considering that COVID-19 vaccines campaign is still ongoing among MS patients, our results might bring new knowledge concerning the safety profile of vaccines in this frail population.