Multiple sclerosis, rituximab, and COVID-19.

We conducted a retrospective cohort study in Kaiser Permanente Southern California from 1 January 2020 to 30 September 2020. We found that rituximab-treated persons with multiple sclerosis (pwMS, n = 1895) were more likely be hospitalized (n = 8, 33.3%), but not die (n = 0) from COVID-19, compared to the 4.81 million non-MS population (5.8% and 1.4%, respectively). Time in months (adjusted OR = 0.32, 95% CI = 0.15-0.69, p = 0.0033) and receiving 1000 mg compared to lower doses at last infusion (adjusted OR = 6.28, 95% CI = 1.38-28.5, p = 0.0173) were independent predictors of COVID-19 severity. Rituximab-treated pwMS should be counseled to take extra precautions in the 5 months following each infusion. Using extended dosing intervals and lower doses could be considered.