NCR1 and influenza: We thank Prof. Eric Vivier (Aix-Marseille, France) for generously supplying breeding pairs of C57BL/6J-NKp46:iCre+/+ mice, the LSHTM animal care staff for their technical assistance, John McCauley and Andreas Wack (Francis Crick Institute) for advice on the mouse influenza model and Christian Bottomley (LSHTM) for statistical advice.