RESUMEN
Since the beginning of the mass immunization with COVID-19 vaccines of patients with multiple sclerosis, many data on the efficacy and safety of these vaccines have been produced. Considering that MS is an autoimmune disease whose pathology can be explained by an altered immune system and that some DMTs seem to be able to decrease the antibody response against COVID-19 vaccines, we carried out this retrospective study with the aim to evaluate the safety in terms of AEFIs occurrence and the antibody response after the third dose of COVID-19 vaccines in people with MS. Third doses were administered from October 2021 to January 2022. Two hundred and ten patients (64.8% female; mean age: 46 years) received the third dose of the mRNA-based COVID-19 vaccine and were included in the study. The majority of patients (n=193) were diagnosed with RRMS and EDSS values were ≤3.0 in 72.4% of them. DMTs most commonly used by included patients were interferon Beta 1-a, dimethyl fumarate, natalizumab and fingolimod. Overall, 160 patients (68.8% female) experienced 294 AEFIs, of which about 90% were classified as short-term, while 9.2% were classified as long-term. The most commonly reported following the booster dose were pain at the injection site, flu-like symptoms, headache, fever and fatigue. Regarding the immune response, consistently with literature data, we found that patients receiving ocrelizumab and fingolimod had lower IgG titer than patients receiving other DMTs.