SARS-CoV-2 third vaccine immune response in MS patients treated with ocrelizumab

The introduction of a third dose vaccination along with new variants of concerns raises questions regarding serology and T-cell responses in patients with MS (pwMS) treated with B-cell depletion who develop attenuated humoral response to vaccines. The aim of this study is to longitudinally evaluate humoral and cellular response to SARS-CoV-2 mRNA vaccine in ocrelizumab-treated pwMS before and following third vaccine dose. Following the third vaccine dose, patients who are low or non-responders following initial vaccination did not increase antibody titers. In HCs and ocrelizumab-treated pwMS, cellular response decreased 6 months following initial vaccination and increased significantly after the third booster.