IFITM2 and infection: Moreover, IFITM2 and 3 are suggested to act as cofactors for SARS-CoV-2 in some cases (41, 42), and we and others also see enhancement of early-lineage isolates and Alpha and Delta infection by IFITM2/3 (Fig. 4) (12, 22, 24, 41, 42), therefore it cannot be excluded that Omicron may similarly exploit IFITMs in some settings.