Patients with multiple sclerosis (MS) or neuromyelitis spectrum disorders (NMOSD) who used rituximab therapy may be more prone to COVID-19 infection and consequently, critical illness and mortality.

Selecting a safe disease modifying therapy (DMT) during the COVID-19 is perplexing. This analytical case series study was aimed to find the incidence rate and progression of SARS-CoV-2 infection in patients with MS or NMOSD who used rituximab therapy.

The patient-reported walking disability, total rituximab injections used, postponed injections, rate of any relapse, and corticosteroids use during the pandemic was recorded in a web-based questionnaire. The data about the COVID-19 pandemic like adherence to self-isolation, any new exposure to an infected person, and the occurrence of indicative symptoms were also gathered.

Recruited subjects were divided into two groups; mild to moderate and critically ill in case of positive test results. The outcomes were assessed as favorable (better/discharged) and unfavorable (deceased).

Two hundred fifty-eight MS or NMOSD patients were enrolled in this study. Out of which, 9 (3.4%) were coronavirus-positive, 5 needed hospitalizations (55.5%), 2 patients needed critical care unit admission (22.2%) and 2 patients deceased (22.2%).

None of the patients ever used corticosteroids. A greater occurrence of coronavirus infection, raised ratio of serious illness and fatality ratio was found in comparison to MS patients who did not receive DMT.

The use of rituximab seems not to be a safe treatment option in MS or NMOSD patients during the COVID-19 pandemic.