Robust T-Cell Responses in Anti-CD20-Treated Patients Following COVID-19 Vaccination: A Prospective Cohort Study

Abstract

Background: Patients treated with anti-CD20 therapy are particularly at risk of developing severe coronavirus disease 2019 (COVID-19); however, little is known regarding COVID-19 vaccine effectiveness in this population. Methods: This prospective observational cohort study assesses humoral and T-cell responses after vaccination with 2 doses of mRNA-based COVID-19 vaccines in patients treated with rituximab for rheumatic diseases or ocrelizumab for multiple sclerosis (n=37), compared to immunocompetent individuals (n=22). Results: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibodies were detectable in only 69.4% of patients and at levels that were significantly lower compared to controls who all seroconverted. In contrast to antibodies, Spike (S)-specific CD4T cells were equally detected in immunocompetent and anti-CD20 treated patients (85-90%) and mostly of a Th1 phenotype. Response rates of S-specific CD8T cells were higher in ocrelizumab (96.2%) and rituximab-Treated patients (81.8%) as compared to controls (66.7%). S-specific CD4and CD8T cells were polyfunctional but expressed more effector molecules in patients than in controls. During follow-up, 3 MS patients without SARS-CoV-2-specific antibody response had a mild breakthrough infection. One of them had no detectable S-specific T cells after vaccination. Conclusions: Our study suggests that patients on anti-CD20 treatment are able to mount potent T-cell responses to mRNA COVID-19 vaccines, despite impaired humoral responses. This could play an important role in the reduction of complications of severe COVID-19.