1 Single dose of Tdap for those not fully vaccinated (see note 1) or. 2  If additional doses of tetanus and diphtheria toxoid-containing vaccines are needed, then children aged 7 through 10 years should be vaccinated according to the catch-up schedule, with Tdap preferred as the first dose.dap will also help protect the mother at time of delivery, making her less likely to transmit pertussis to her infant. It is important that all family members and caregivers of the infant are up-to-date with their pertussis vaccines (DTaP or Tdap, depending on age) before coming into close contact with the infant.