RESUMEN
BACKGROUND AND PURPOSE: An enhanced severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine regimen could improve humoral vaccine response in patients with multiple sclerosis (MS) treated by anti-CD20. The aim was to evaluate the serological response and the neutralizing activity after BNT162b2 primary and booster vaccination in MS patients, including patients on anti-CD20 receiving a primary vaccine regimen enhanced with three injections. METHODS: In this prospective longitudinal cohort study of 90 patients (47 on anti-CD20, 10 on fingolimod, 33 on natalizumab, dimethylfumarate or teriflunomide), anti-SARS-CoV-2 receptor binding domain (RBD) immunoglobulin G antibodies were quantified and their neutralization capacity was evaluated by enzyme-linked immunosorbent assay (GenScript) and a virus neutralization test against B.1 historical strain, Delta and Omicron variants, before and after three to four BNT162b2 injections. RESULTS: After the primary vaccination scheme, the anti-RBD positivity rate was strongly decreased in patients on anti-CD20 (28% [15%; 44%] after two shots, 45% [29%; 62%] after three shots) and fingolimod (50% [16%; 84%]) compared to other treatments (100% [90%; 100%]). Neutralization activity was also decreased in patients on anti-CD20 and fingolimod, and notably low for the Omicron variant in all patients (0%-22%). Delayed booster vaccination was performed in 54 patients, leading to a mild increase of anti-RBD seropositivity in patients on anti-CD20 although it was still lower compared to other treatments (65% [43%; 84%] vs. 100% [87%; 100%] respectively). After a booster, Omicron neutralization activity remained low on anti-CD20 and fingolimod treated patients but was strongly increased in patients on other treatments (91% [72%; 99%]). DISCUSSION: In MS patients on anti-CD20, an enhanced primary vaccination scheme moderately increased anti-RBD seropositivity and anti-RBD antibody titre, but neutralization activity remained modest even after a fourth booster injection. TRIAL REGISTRATION INFORMATION: COVIVAC-ID, NCT04844489, first patient included on 20 April 2021.