IFNA2 and influenza: The presence of auto-Abs neutralizing high concentrations of IFN-α2 only or low concentrations of both IFN-α2 and IFN-ω resulted in a 20–80 times higher risk of developing critical influenza in patients <70 yr, whereas the presence of auto-Abs neutralizing low concentrations of IFN-α2 only resulted in an almost seven times higher risk of developing critical influenza in patients <70 yr (Fig. 2 B).