ACE2 and COVID-19: However, these decreases in circulating ACE2 full-length species noticed in moderate COVID-19 patients reflect the generalized SARS-CoV-2 infection and no particular changes in the CNS, since these decreases affect all the circulating full-length ACE2 species, each of which probably reflects a particular contribution of different tissues/cells expressing different ACE2 isoform patterns [13].