Neutralizing antibody responses against SARS-CoV-2 in vaccinated people with multiple sclerosis

BACKGROUND: Patients with multiple sclerosis (pwMS) are often treated with disease modifying therapies (DMT) with immunomodulatory effects. This is of particular concern following the development of several vaccines to combat coronavirus disease 19 (COVD-19), a potentially fatal illness caused by SARS-CoV-2. OBJECTIVES: To determine the efficacy of SARS-CoV-2 vaccination in pwMS and the impact of disease modifying therapies (DMT) on vaccine response. METHODS: This is a prospective longitudinal study in pwMS. Longitudinal serum samples were obtained prior to, and after SARS-CoV-2 mRNA vaccination. A novel neutralizing antibody (nAb) assay was used to determine nAbs titres against SARS-CoV-2 spike. RESULTS: We observed that (1) pwMS on B-cell depleting therapies exhibited reduced response to vaccination compared to other pwMS, correlating with time from last anti-CD20 infusion, (2) prior COVID-19 illness, DMT category, and pyramidal function were significant predictors of vaccine responsiveness, and (3) circulating absolute lymphocyte count (ALC) and IgG levels correlated with nAb levels. CONCLUSIONS: We demonstrate that pwMS exhibit reduced nAb response to mRNA vaccination dependent on DMT status and identify predictive biomarkers for vaccine efficacy. We conclude that additional vaccination strategies may be necessary to achieve protective immunity in pwMS.