F2 and pertussis: Low vaccination coverage, low anti-pertussis herd immunity in target population, antigenic drift, genetic shift, and gene loss in pertussis pathogens (e.g., novel PT promoter allele of pertussis toxin, and pertactin-deficient isolates), epidemiological changes (circulating of new clones) under vaccine selection pressure, and lower efficacy of the DTaP compared with the DTwP are the main causes of pertussis resurgence (Nian et al., 2023; Fullen et al., 2020).