Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic represents one of the most challenging issues that have recently influenced everyday life in countries all over the world. Understanding the risk of this disease is of high importance in patients with multiple sclerosis (MS) as they represent a vulnerable population through their treatment with disease-modifying therapies (DMTs). Infective episodes may trigger relapses and lead to deterioration of the health condition. Summary: Vaccination is an important preventive measure against infectious diseases. In MS patients concerns have been raised about the effectiveness of vaccines in patients on various immunomodulatory drugs and about their possible adverse effects including impairment of neurological functions. The objective of this article is to summarize the current knowledge on immune responses to the COVID-19 vaccines and their safety in MS patients and to provide practical guidance based on the data available to date. Key Messages: Although MS is not associated with a higher risk of COVID-19, this infection can trigger relapses or pseudo-relapses. Vaccines against SARS-CoV-2 are recommended for all MS patients who are not in the active phase of the disease, despite the fact that there is still a lack of long-term reliable data on the effectiveness and safety of vaccines against COVID-19. Some DMTs can reduce vaccine humoral responses, but might still provide some protection and adequate T cell response. To optimize the effectiveness of vaccination, the ideal timing of vaccine application and DMTs dosing regimen is crucial.

The Author(s). Published by S. Karger AG, Basel