These observations indicate that the surprisingly narrow range of severe viral diseases in patients with autosomal recessive IRF7, IFNAR1 or IFNAR2 deficiency54–57, which seem to be restricted to certain viral diseases of the lungs and brain, and adverse reactions to certain live-attenuated viruses, may be due to the existence of many other type I IFN-independent restriction factors specific for different viruses in different tissues. Here, IFNAR1 is linked to viral load.