To support the analysis of pertussis, tetanus, and diphtheria immunity in the context of maternal-infant immunization, we have developed and qualified an MSD multiplex assay that allows simultaneous quantification of vaccine-induced antibodies, specifically, serum IgG directed against pertussis PT, PRN, FHA, FIM 2/3, as well as tetanus and diphtheria antitoxin. The gene discussed is F2; the disease is diphtheria.