C3 and COVID-19: In our cohort, besides the fact that about 27% of COVID-19 patients (i.e., 3 of the 11) presented with bacterial superinfection on admission, we should note that the overwhelming complement activation in COVID-19 patients compared to patients with bacterial sepsis suggests that SARS-CoV-2 infection is the predominant factor for the increase in C3a and C5a.