Reactivation of SARS-CoV-2 after Rituximab in a Patient with Multiple Sclerosis.

A 32-year-old woman with highly active MS was infected with SARS-CoV-2 while on treatment with rituximab. She recovered and was symptom-free for 21 days before receiving rituximab and IVIg for comorbid hypogammaglobulinemia. Three days after the infusion she redeveloped respiratory symptoms and required admission. Three SARS-CoV-2 nasopharyngeal swabs and antibody testing was negative; however, bronchial alveolar lavage detected SARS-CoV-2. Reactivation of SARS-CoV-2 after rituximab for MS has not been reported but is a known risk in other conditions. The timing of anti-CD20 treatment after SARS-CoV-2 infection requires further investigation and individual consideration to reduce the risk of reactivation.