It may not be coincidental that these 4 etiologies impair both type I and type III IFN immunity, whereas critical influenza pneumonia has only been reported in 1 of the 29 known patients with IFNAR1 or IFNAR2 deficiency (19–21, 24–33) and in none of the more than 30 patients with IL10RB deficiency (55–58). This evidence concerns the gene IFNA1 and influenza.