We read with great interest the recent article by Fiedman and Winthrop reporting a patient with granulomatosis with polyangiitis (GPA) being treated with rituximab (RTX), recurrent SARS-CoV-2 disease 2019 (COVID-19) and no detectable SARS-CoV-2 seroresponse after recovery.1 Anti-CD20 therapy impairs humoral response, theoretically increasing the risk of prolonged SARS-CoV-2 infection and shedding as well as subsequent reinfection.1–3 We have recently reported a patient with GPA under maintenance therapy with RTX and SARS-CoV-2 infection.4 Here, we report further details on anti-CD20 therapy with RTX, serological response to SARS-CoV-2 infection, virus elimination and corresponding B cell numbers. This case highlights that B cell numbers in patients with rheumatic diseases treated with RTX could associate with serological response to SARS-CoV-2 infection, which is particularly relevant as RTX may also impair the immunogenicity of SARS-CoV-2 vaccines.

An 80-year-old man had received a diagnosis of GPA in 2014 with biopsy-confirmed renal vasculitis and no history of pulmonary manifestation. After remission induction therapy, he received RTX at a dose of 500 mg every 6 months as maintenance therapy. The last …