IL17A and infection: We speculate that Th17 cells, which are adaptive immune cells, do not develop in neonates because of the lack of SFB,[71] whereas γδT cells and ILC3s are innate immune cells that are abundant in neonatal mice.[4, 8] IL‐17A is produced early after infection by pathogens, which indicates the presence of innate IL‐17A secretion pathways.