In a murine model of X31 influenza infection, neutrophils peak in the airways at 24 hours post infection (figure 1A), coinciding with peak viral titres (24–48 hours) but preceding peak illness and inflammation (day 6).29 BALF IL-1β levels longitudinally mapped with neutrophil infiltrate during influenza infection (figure 1A), and there was a significant correlation between IL-1β levels and neutrophil numbers at 24 hours post infection (figure 1B). Here, IL1B is linked to infection.