multiple sclerosis(14) Patient(12) multiple sclerosis.(12) humoral immune response(11) analysed(11) COVID-19(11) SARS-CoV-2(9) Infection(9) titre(8) vaccination(7) receiving(7) therapy(7) B cell(7) patients(7) IgG(7) Immune cell(7) risk(7) T cell response(7) disorder(6) Infectious diseases(6) cohort of patient(5) clinical neurology(5) collected(5) COVID-19 severity(4) profile(4) time(4) SARS-CoV-2 antibody(4) SARS-CoV-2 vaccine(4) groups(4) seropositive(4)