The loss of age-dependent differences during the first days of infection in Ifngr1−/− mice supports our previous findings obtained by transcriptional profiling (Figs. 1 H and 5, B and C), which suggested a relevant contribution of an early and potent IFN-γ response to prevent SARS-CoV-2–induced disease in adult mice. This evidence concerns the gene IFNGR1 and infection.