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.