IRF7 and viral infectious disease: Although the first findings can be explained by an age-associated impairment in the phosphorylation of interferon regulatory factor 7 (IRF-7) and a reduced function of plasmacytoid dendritic cells in older adults, which are responsible for controlling viral infection through the release of IFN-λ [29], the second suggests that the severe course of COVID-19 may be influenced by other agents.