Impact and cost-effectiveness of a second tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine dose to prevent pertussis in the United States

A second dose of Tdap resulted in a slight decrease in the number of cases and other outcomes, and that trend is more apparent when revaccinating at age 16 years than at age 21 years. Both revaccination strategies had high dollar per QALY saved even under optimistic assumptions in a multivariate sensitivity analysis.