ACE2 and infection: Macrophages express Angiotensin-Converting Enzyme 2 (ACE2) receptors, making it possible for SARS-CoV-2 to directly infect them, and, as COVID-19 severity increases, activated macrophages congregate in the lungs, where even if not productively infected, an abortive infection of macrophages by SARS-CoV-2 is sufficient to induce cytokine storm [54,59,60].