de Cellès MD, et al. - In this simulation study, researchers used a mathematical, age-structured model of pertussis transmission, validated empirically on incidence data in Massachusetts, to evaluate the effectiveness and length of immunity of the diphtheria-tetanus–acellular pertussis (DTaP) vaccines in US children. Based on metrics documented in US epidemiological studies, in children aged 5 to 9 years, vaccine efficacy was estimated to exceed 75%. Findings indicate that temporal trends in the odds of acquiring pertussis are an unreliable measure of vaccine-induced protection durability. They also show that DTaP vaccines provide flawed but long-lasting protection. They suggested that control strategies should be based on the best available estimates of vaccine properties and the age structure of the transmission network.