Although respiratory viruses, including influenza virus (ssRNA), are limited to the airways during infection and have been reported to impact systemic immunity and the intestinal microbiota.122, 123 Indeed, immunity and microbiota of the gut and lungs are closely interlinked.124 In humans, the microbiome of the upper respiratory tract, including nose and throat, has been shown to change upon influenza infection.125 Whether intestinal ILC populations are affected in influenza infection in humans has not yet been addressed. Here, CCL27 is linked to influenza.