Author response to: Correspondence to humoral immune response to COVID-19 mRNA vaccine in patients with multiple sclerosis treated with high-efficacy disease-modifying therapies

To the Editor,

We read the letter by Piquet, Corboy, and Vollmer related to our recent paper on the humoral immune response to COVID-19 mRNA vaccine in patients with multiple sclerosis treated with high-efficacy disease-modifying therapies, ¹ but did not find any relevant data they provide to support their criticism, except for theoretical considerations.

Indeed, our findings have major implications related to MS patients treated with ocrelizumab and fingolimod. As we showed in our study, these patients failed to develop an appropriate humoral immune response following COVID-19 vaccination and therefore are not protected against SARS-COV-2 infection, in contrast to healthy subjects, untreated MS patients, and MS patients treated with cladribine. Our recommendations are based on the currently obtained data. Theoretically, even if some of the ocrelizumab and fingolimod-treated MS patients will be able to develop a T-cell response, we doubt that this response will be protective in the absence of B cells.