Immunology of COVID‐19 and disease‐modifying therapies: the good, the bad and the unknown

Zrzavy, T.; Wimmer, I.; Rommer, P. S.; Berger, T.

The outbreak of the SARS‐CoV‐2 pandemic, caused by a previously unknown infectious agent, posed unprecedented challenges to healthcare systems and unmasked their vulnerability and limitations worldwide. Patients with long‐term immunomodulatory/suppressive therapies, as well as their physicians, were and are concerned about balancing the risk of infection and effects of disease‐modifying therapy. Over the last few months, knowledge regarding SARS‐CoV‐2 has been growing tremendously, and the first experiences of infections in patients with multiple sclerosis (MS) have been reported. This review summarizes the currently still limited knowledge about SARS‐CoV‐2 immunology and the commonly agreed modes of action of approved drugs in immune‐mediated diseases of the central nervous system (MS and neuromyelitis optica spectrum disorder). Specifically, we discuss whether immunosuppressive/immunomodulatory drugs may increase the risk of SARS‐CoV‐2 infection and, conversely, may decrease the severity of a COVID‐19 disease course. At present, it can be recommended in general that none of those therapies with a definite indication needs to be stopped per se. A possibly increased risk of infection for most medications is accompanied by the possibility to reduce the severity of COVID‐19. Despite the knowledge gain over the last few months, current evidence remains limited, and, thus, further clinical vigilance and systematic documentation is essential.