The Chinese team first discovered that macaques and mice have ACE2 genes suitable for SARS-CoV-2 studies; the Beijing Union Medical College and Wuhan Virus Institute in China have successfully infected human ACE2 transgenic mice with SARS-CoV-2, which showed some infection symptoms; Guangzhou Medical University have established nontransgenic COVID-19 infected pneumonia mouse models; Wuhan Virus Institute has preliminarily established primate models. Here, ACE2 is linked to susceptibility to pneumonia measurement.