ACE2 and heart failure: Although its relation with tissue levels may vary, plasma levels of the COVID-19 receptor in human cells, ACE2, were significantly higher in males compared with females in a recent study of patients with heart failure, consistently with the increased susceptibility and more severe clinical course of COVID-19 in men.15 Taken together all these intrinsic biological factors could explain the higher virulence of COVID-19 in men.13