How should we schedule DTaP for a child with a history of only DT?

If DTaP is not contraindicated and the child has not received all of the age-appropriate doses of pertussis-containing vaccine, it would be best to try to administer as many doses of DTaP as possible before the child reaches his 7th birthday in order to confer protection against pertussis. Give additional doses of DTaP with 4-week intervals until you achieve 3 total doses. Then, give additional doses with 6-month intervals, not to exceed 6 total doses of diphtheria- and tetanus-containing vaccine by the child’s 7th birthday.