TMPRSS2 and COVID-19: Its high expression is a predictor of an enhanced efficiency of SARS-CoV-2 infection and greater severity of COVID-19.30 Aligned with the observation in nasal samples, TMPRSS2 (q = 9.8 × 10−7) showed significant upregulation in SARS-CoV-2-positive squamous cells isolated from male BALF and sputum comparing to females (Supplementary Fig. 7a); yet, TMPRSS2 expression did not correlate with SARS-CoV-2 viral load (viral reads per million, Supplementary Fig. 7b).