For example, examining the efficacy of recombinant human ACE2 to act as a decoy receptor or the effect of “ACE inhibitors” in patients with, or at risk for, COVID-19 will require careful experimentation in appropriate models together with well-controlled clinical trials (Hofmann et al., 2004, Monteil et al., 2020, Vaduganathan et al., 2020). Here, ACE is linked to COVID-19.