TMPRSS2 and COVID-19: As a caveat to these observations, it should be noted that a comparably homologous protein, the serine protease from Pseudomonas bacteria, may exhibit similarly competitive prospects for circumventing TMPRSS2 action on SARS-CoV-2 Spike proteins, even though there is little evidence for Pseudomonas strains exerting a net protective effect against COVID-19.