CD79A and infection: Collectively, our study revealed three major findings: (1) Macronutrient composition remained stable post-infection, ensuring nutritional continuity for infants despite maternal illness; (2) SARS-CoV-2-specific IgA and IgG exhibited biphasic kinetics with prolonged plateau phases, indicating sustained antiviral immunity in breast milk; and (3) proteomic signatures reflected a transition from early cell-mediated to late humoral immunity, with 24 proteins showing conserved responses across variants and 13 proteins with variant-specific response.