Protracted severe COVID-19 pneumonia following rituximab treatment: caution needed.

The outcomes of COVID-19 in patients treated with biologic agents are a subject of intense investigation. Recent data indicated that patients under rituximab (RTX) may carry an increased risk of serious disease. We performed an electronic search in Medline and Scopus using the keywords rituximab and COVID-19. We present a rare case of severe, protracted COVID-19 pneumonia in a patient with mixed connective tissue disease (MCTD) who was infected a few days following RTX treatment. In a relevant literature search, we identified 18 cases of patients with rheumatic diseases (6 RA, 8 ANCA vasculitis, 3 systemic sclerosis and 1 polymyositis) treated with RTX who experienced an atypical and/or prolonged course of COVID-19 pneumonia with no evidence of cytokine storm. Our case indicates that RTX may unfavorably affect outcomes following SARS-CoV-2 infection. B cell depletion may dampen the humoral response against the virus; we may hypothesize that B cell-depleted patients may be protected from cytokine storm but on the other hand may have difficulties in virus clearance leading to a protracted course. Taking into account that COVID-19 vaccines are available we may consider delaying RTX infusions at least in patients without life threatening disease, until vaccination is completed.