TMPRSS2 and COVID-19: Camostat mesylate, a protease inhibitor that prevents proteolytic priming of SARS-CoV-2 spike protein by TMPRSS2 to enable ACE2 binding, is still under investigation as an intervention for COVID-19 (ClinicalTrials.gov Identifiers NCT04353284, NCT04524663, NCT04470544, and others).