TLR7 and susceptibility to pneumonia measurement: The burden of proof can be provided experimentally via biochemical, virological, and immunological experiments, as our previous studies of TLR7 in which we showed that biochemically deleterious TLR7 variants blunted the pDC-dependent sensing of SARS-CoV-2 and induction of type I IFN, thereby accounting for ~ 1% of critical pneumonia cases in men [30].