In the last 13 years, major pertussis epidemics have occurred in the United States, and numerous studies have shown the deficiencies of DTaP vaccines, including the small number of antigens that the vaccines contain and the type of cellular immune response that they elicit. The type of cellular response a predominantly, T2 response results in less efficacy and shorter duration of protection. Because of the small number of antigens (3-5 in DTaP vaccines vs >3000 in DTwP vaccines), linked-epitope suppression occurs. Because of linked-epitope suppression, all children who were primed by DTaP vaccines will be more susceptible to pertussis throughout their lifetimes, and there is no easy way to decrease this increased lifetime susceptibility.
Source: Cherry JD. J Pediatric Infect Dis Soc. 2019.. https://www.ncbi.nlm.nih.gov/m/pubmed/30793754/?fbclid=IwAR003oadubh3_0FrE_7TBZFXx9zGixpK0IxuNpTJrFhF2SBW2RD9yLOLmBs