FCGR2A and avian influenza: In a separate set of children’s samples in sub-study (iv) (Fig. 5a, Table 1), including samples pre/post-vaccination, and pre/post-infection, we increased our protein panel to 19 seasonal and avian influenza HA proteins (Supplementary table 1) to determine antibody binding breadth (for IgG, IgG1, IgG3, IgA1, IgM, FcγR3a and FcγR2a binding).