Moreover, male hamsters exhibit more severe lung lesions than females and less efficient antibody responses.378,859 Indeed, male COVID-19 patients exhibit greater levels of proinflammatory cytokines and reduced T-cell-mediated immunity than female patients.860 Mouse-adapted SARS-CoV-2 and ACE2 transgenic mice also develop pathological signs of pneumonia that range from mild to severe. Here, ACE2 is linked to COVID-19.