ECTRIMS 2021 – Late Breaking News Oral Presentations

Introduction: In patients with Multiple Sclerosis (pwMS) disease- modifying therapies (DMTs) are known to affect immune response antigens and possibly SARS-CoV2 vaccine. Therefore, post-vaccination serological assessments needed evaluate the effect of vaccine on SARS-CoV-2 antibody response. Objectives aims: We designed a prospective multicenter cohort study enrolling pwMS who were scheduled for SARSCov- 2 vaccination mRNA vaccines (BNT162b2, Pfizer/ BioNTech, Inc or mRNA-1273, Moderna Tx, Inc) their Methods: A blood collection measure before first dose 4 weeks after second was planned, centralized blinded assessment (electrochemiluminescence immunoassay, ECLIA, Roche Diagnostics). Results: Preliminary data collected 780 (76% BNT162b2 24% mRNA-1273) had pre- 4-week assessments. 87 (11.2%) untreated, 154 (19.7%) ocrelizumab, 25 (3.2%) rituximab, 85 (10.9%) fingolimod, cladribine 404 (51.7%) other DMTs. 677 (86.8%) detectable antibodies. At multivariate analysis, levels ocrelizumab (178-fold decrease, p<0.001), fingolimod (26-fold p<0.001) rituximab (17-fold significantly reduced as compared untreated patients. Vaccination mRNA-1273 resulted in systematically 3.5-fold higher level than (p<0.001). Interpretation: pwMS, anti-CD20 treatment led humoral mRNA-based vaccines. As elicits 3.5-higher BNT162b2, this may be preferentially considered under fingolimod. Combining our those that will produced by studying cellular vaccines, including clinical follow-up, contribute better define most appropriate strategies context DMTs MS. time ECTRIMS presentation full sample (about 2000 subjects) presented.