The median log10 pre-F IgA antibody titer of the breast milk sample at the latest time point prior to infection did not differ significantly in breast milk of mothers of cases (median, 1.7 [IQR, 0.0–2.2] log10 ng/mL) compared with mothers of controls (median, 1.7 [IQR, 1.2–2.1] log10 ng/mL) (P = .58; Figure 1B). Here, CD79A is linked to infection.