An imbalance between the Ang-converting enzyme/Ang II/Ang II type 1 receptor (ACE/Ang II/AT1R) and ACE2/Ang-(1–7)/Mas receptor [ACE2/Ang-(1–7)/MasR] pathways and the loss of ACE2 are critical contributing factors to multisystem inflammation9–11, which promotes severe pneumonia and notable mortality in SARS-CoV-infected patients10. Here, ACE2 is linked to pneumonia.