The interferon landscape along the respiratory tract impacts the severity of COVID-19

In the upper respiratory tract of COVID-19 patients with mild symptom, high level expression of IFN-III was characteristic that led to the efficient driving of IFN-stimulated gene associated with protection against  SARS-CoV-2 even in the case of high viral burden. In contrast, for severe case of COVID-19, overrepresentation of IFNs were remarkable in the lower respiratory tract,  associated with increased apoptosis and decreased proliferation. These data demonstrated that IFNs play opposing roles at distinct anatomical sites.