The emergency represented by the COVID-19 pandemic represents a new challenge for clinicians who deal with autoimmune diseases because of patients undergoing immunosuppressive therapy. Few cases of Multiple Sclerosis (MS) patients receiving ocrelizumab who contracted COVID-19 with a benign course have recently been published. We present the case of a MS patient with mild COVID-19 who developed SARS-CoV-2 specific IgA without IgG ten weeks after infection. Patients on B-cell depleting drugs have a reduced antibody immune response to viral neoantigens. A relative sparing of mucosal-associated lymphoid tissues (MALT) could be responsible for IgA response in our patient.