TLR3 and susceptibility to pneumonia measurement: The TLR3 gene polymorphism rs5743313/CT, causing loss of function, might be linked to an increased risk of pneumonia in children during infection with A/H1N1/2009 influenza virus [63], and severe acute respiratory distress syndrome was reported in children with inherited TLR3 deficiency [64], suggesting a protective role of TLR3 in IAV infection.