ACE2 and infection: It is noteworthy that SARS-CoV also uses ACE2 as a receptor for cell entry; however, receptor binding ability of SARS-CoV-2 is 10- to 20-fold higher than that of SARS-CoV, and the number of infections with SARS-CoV-2 has exceeded that of SARS infections during the outbreak in China in 2002/2003, indicating higher transmission rates.