In contrast, prevaccination IgA breadth, but not magnitude, to Cal09 H1 and N1 peptides was significantly lower in individuals with obesity (Fig. 3C, D, G, and H), as well as prevaccination IgA breadth to H1 proteins (Fig. S3B) and postvaccination IgA breadth to A/H1N1 viruses (Fig. S3D). Here, CD79A is linked to obesity due to melanocortin 4 receptor deficiency.