In terms of the gastrointestinal and respiratory tracts—the infection sites for most of the important pathogens for children—the gut-associated lymphoid tissue (GALT) and nasopharyngeal-associated lymphoid tissue (NALT) play central roles in the induction of protective immunity (e.g., mucosal secretory IgA and systemic serum IgG) against pathogens and vaccine antigens at the mucosa [3,25,26]. Here, CD79A is linked to infection.