selection in an animal host (ie, intermediary species) such that it acquires features affording tropism to human tissue. To date, the intermediate host for SARS-CoV-2 is not known, however, a closely related coronavirus to SARS-CoV-2 has been identified in Malayan pangolins.4 Moreover, it remains to be established whether SARS-CoV-2 has acquired genomic changes within an intermediate animal host before the occurrence of human transmission, or whether a SARS-CoV-2 progenitor may have undergone genomic changes during undetected human-to-human transmission, ultimately resulting in the current pandemic.3
In humans, these coronaviruses gain entry into host cells by way of their transmembran