C5AR1 and COVID-19: Since C5a/C5aR1 signaling seems to be involved in the immunopathology of COVID-19, we sought to test the efficacy of DF2593A, an orally acting and selective C5aR1 allosteric antagonist (41), on SARS-CoV-2–infected Tg mice to explore this candidate for the treatment of COVID-19.