IFNL1 and susceptibility to pneumonia measurement: IL‐29 exerts a variety of immunomodulatory effects on various cell types.10, 13, 14, 15 In recent years, several reports have shed light onto the type III IFN system and its role during viral infections such as airway‐inflammation16 or hepatitis.17 Reduced production of IFN‐α in response to RSV infection is associated with a significant increase in the frequency of upper respiratory infections and pneumonia.18 Important cellular players of innate immune responses fighting viral pathogens are pDCs.