Catch-Up Vaccination Guidelines for Unvaccinated Children
For unvaccinated children, follow age-specific catch-up schedules without restarting the series regardless of time elapsed between doses, using DTaP for children under 7 years and Tdap as the first dose for those 7-18 years, with subsequent doses using Td vaccine. 1
Age-Specific Catch-Up Protocols
Children 2 Months to 6 Years
Use DTaP vaccine exclusively for all catch-up doses in this age group, administered as 0.5 mL intramuscularly in the anterolateral thigh (infants through age 2) or deltoid muscle (age ≥3 years). 2
Never restart the series regardless of how much time has elapsed between doses—simply continue from where the child left off using the catch-up schedule. 1
Do not exceed 6 total doses of diphtheria and tetanus toxoid-containing vaccines (DTaP, DT, or DTP) before the seventh birthday; only documented doses count toward this maximum. 1
Follow minimum intervals between doses as specified in the CDC catch-up schedule at https://www.cdc.gov/vaccines/schedules/hcp/child-adolescent.html. 1
Children and Adolescents 7-18 Years
Give Tdap as the first dose (preferably) of the catch-up series, administered as 0.5 mL intramuscularly into the deltoid muscle. 1, 2
Use Td vaccine for any additional needed doses after the initial Tdap dose. 1
For ages 7-10 who receive Tdap during catch-up: Still administer another Tdap dose at age 11-12 years as the routine adolescent booster. 1, 3
Never restart the series regardless of time elapsed between doses. 1
Special Catch-Up Scenarios for Ages 7-10
Children who never received any tetanus-containing vaccine: Give 3 doses of Td (dose 2 at ≥4 weeks after dose 1, dose 3 at 6-12 months after dose 2), with one dose being Tdap if age 10 or older. 1
Children with incomplete DTaP history: Continue the series using Tdap for the first catch-up dose, then Td for remaining doses. 1
Adults Over 18 Years
Never vaccinated adults: Give a 3-dose series with one dose being Tdap (preferably first): Tdap, then Td at ≥4 weeks, then Td at 6-12 months. 1, 3
Partially vaccinated adults: Give Tdap as the first dose in the catch-up series, then complete with Td as needed. 1
Alternative for uncertain vaccination history: Consider serologic testing for tetanus and diphtheria antibodies; if both antitoxin levels are >0.01 IU/mL, give only a single Tdap dose. 1
Critical Implementation Points
Vaccine Selection Errors
If DTaP given inadvertently to a fully vaccinated child aged 7-10: Count this dose as the adolescent Tdap dose. 2
If Tdap given inadvertently instead of DTaP in children under 7: Do not count as valid; give a replacement DTaP dose. 2
If Tdap given as the fourth dose in a child under 7: Give a fifth dose using DTaP on the usual schedule. 1
No Minimum Interval Required
- Administer Tdap when indicated regardless of interval since the last tetanus-containing vaccine—protection against pertussis outweighs potential increased local reactions from shorter intervals. 2, 3
Ongoing Maintenance After Catch-Up
After receiving Tdap: All subsequent routine boosters should be Td every 10 years. 2, 3
Tdap is a single-dose vaccine for the general population (except pregnancy), not for repeated administration. 3
Common Pitfalls to Avoid
Do not restart vaccination series when encountering children with delayed or incomplete vaccination—this is the most common error and leads to unnecessary doses and potential adverse reactions. 1
Do not give more than 6 doses of tetanus-diphtheria toxoid-containing vaccines before age 7, as this increases risk of adverse reactions. 1
Do not use DTaP for children ≥7 years—switch to Tdap/Td formulations at this age threshold. 2
Do not forget the second Tdap dose for children who received Tdap during catch-up at ages 7-10; they still need the routine adolescent dose at 11-12 years. 1, 3