AUTHOR=van Dam Koos P. J. , Hogenboom Laura , Stalman Eileen W. , Kummer Laura Y. L. , Steenhuis Maurice , Keijser Jim B. D. , Brinke Anja ten , van Ham S. Marieke , Kuijpers Taco W. , Rispens Theo , Wieske Luuk , Eftimov Filip , Strijbis Eva M. , Killestein Joep , van Kempen ZoƩ L. E. TITLE=Longitudinal SARS-CoV-2 humoral response in MS patients with and without SARS-CoV-2 infection prior to vaccination JOURNAL=Frontiers in Neurology VOLUME=Volume 13 - 2022 YEAR=2022 URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2022.1032830 DOI=10.3389/fneur.2022.1032830 ISSN=1664-2295 ABSTRACT=Introduction: During the COVID-19 pandemic, certain disease modifying therapies (DMTs) used in multiple sclerosis (MS), such as anti-CD20 therapies, have been associated with decreased humoral responses after SARS-CoV-2 vaccination. Hybrid immunity, referring to immunity after both vaccination and SARS-CoV-2 infection, might increase humoral responses. Methods: This was a substudy of two prospective cohort studies on SARS-CoV-2 antibodies after SARS-CoV-2 infection and vaccination. RBD-specific IgG titers of patients with MS and healthy controls who had experienced SARS-CoV-2 infection prior to first vaccination were compared to those in patients and healthy controls without prior infection. Humoral responses were measured at various time points after SARS-CoV-2 infection in convalescent patients and in all patients prior to first vaccination, 28 days after first vaccination and 28 days after second vaccination. Results: 102 individuals (of which 34 MS patients with DMTs (natalizumab or ocrelizumab), 30 without DMTs and 38 healthy controls) were included. 51 of these individuals were convalescent. Median SARS-CoV-2 antibody titers were higher after first vaccination in convalescent individuals compared to individuals without infection prior to vaccination. SARS-CoV-2 antibody titers were comparable after second vaccination in MS patients with and without prior infection. However, in the convalescent ocrelizumab treated patients, SARS-CoV-2 antibody titers did not increase after vaccinations. Conclusion: In patients with MS without anti-CD20 therapies, SARS-CoV-2 infection before vaccination increases humoral responses after the first vaccination, similar to healthy controls. In MS patients treated with ocrelizumab (convalescent and non-convalescent), humoral responses remained low.