Immunogenicity and safety of mRNA COVID-19 vaccines in people with multiple sclerosis treated with different disease-modifying therapies

The potential impact of disease-modifying therapies (DMTs) for multiple sclerosis (MS) on COVID-19 vaccination is poorly understood. According to recent observations, the humoral immune response could be impaired in patients treated with ocrelizumab or fingolimod. Our study evaluated the immunogenicity and safety of mRNA COVID-19 vaccines in a convenience sample of 140 MS patients treated with different DMTs, undergoing vaccination between April and June 2021. Humoral immune response was tested 1 month after the second dose, using a chemiluminescent microparticle immunoassay to detect IgG against SARS-CoV-2 nucleoprotein. We explored the potential correlation between the IgG titer and DMTs. All patients in treatment with first-line DMTs, natalizumab, cladribine, and alemtuzumab, developed a measurable humoral response. In patients treated with ocrelizumab and fingolimod, the IgG level was significantly lower, but only some patients (22.2% for fingolimod and 66% for ocrelizumab) failed to develop a measurable humoral response. In the ocrelizumab group, the IgG level was positively correlated with the time from last infusion. No SARS-CoV-2 infections were reported after vaccination. The most reported side effects were pain at the injection site (57.1%) and fatigue (37.9%). No patient experienced severe side effects requiring hospitalization. Our study confirms that COVID-19 vaccination is safe and well-tolerated in MS patients and should be recommended to all patients regardless of their current DMTs. Since fingolimod and ocrelizumab could reduce the humoral immune response, in patients treated with these drugs, detecting SARS-CoV-2 antibodies could be helpful to monitor the immune response after vaccination.