IFITM3 and COVID-19: Compared with healthy controls, ILC1s, ILC2s and ILCps from COVID-19 patients downregulated expression of IFITM2 as well as IFITM3. Although interferon-induced transmembrane proteins (IFITMs 1, 2 and 3) have been shown to restrict infection by viral pathogens such as dengue, influenza A and Ebola virus (28), pro-viral functions of IFITM proteins have been reported for coronaviruses.