What is DTaP?
DTaP is a combination vaccine that protects against diphtheria, tetanus, and pertussis (whooping cough) using acellular pertussis antigens, specifically formulated for children aged 6 weeks through 6 years. 1
Vaccine Composition and Formulation
DTaP contains three key components 1:
- Diphtheria toxoid: 15-25 Lf (limit of flocculation) units, depending on manufacturer
- Tetanus toxoid: 5-10 Lf units
- Acellular pertussis antigens: Variable amounts of purified bacterial components including pertussis toxoid (PT), filamentous hemagglutinin (FHA), pertactin (PRN), and sometimes fimbriae
The acellular pertussis component distinguishes DTaP from the older whole-cell DTP vaccine, resulting in substantially fewer adverse reactions while maintaining high efficacy 1.
Licensed DTaP Products in the United States
Two standalone DTaP vaccines are currently available 1:
- Infanrix (GlaxoSmithKline): Licensed for all 5 doses in the series for children aged 6 weeks through 6 years
- Daptacel (Sanofi Pasteur): Licensed for all 5 doses in the series for children aged 6 weeks through 6 years
Four combination vaccines containing DTaP are also available 1:
- Pediarix (DTaP-IPV-HepB): For the first 3 doses starting at 6 weeks
- Kinrix (DTaP-IPV): For the 5th DTaP dose at ages 4-6 years
- Pentacel (DTaP-IPV/Hib): For 4-dose series at 2,4,6, and 15-18 months
- Quadracel (DTaP-IPV): For the 5th DTaP dose at ages 4-6 years
Recommended Vaccination Schedule
The CDC and American Academy of Pediatrics recommend a 5-dose DTaP series 1:
- Primary series: 3 doses at ages 2,4, and 6 months
- First booster: At 15-18 months (≥6 months after the 3rd dose)
- Second booster: At 4-6 years before school entry
A 5th dose is not necessary if the 4th dose is administered on or after the 4th birthday 1.
For accelerated schedules (travel, increased pertussis exposure risk), doses can begin as early as 6 weeks of age with minimum 4-week intervals between doses 1.
Key Distinction from Tdap
DTaP differs fundamentally from Tdap in antigen content and target population 2:
- DTaP: Contains higher quantities of diphtheria toxoid (15-25 Lf) and pertussis antigens, designed for children <7 years
- Tdap: Contains reduced quantities (10-50% of DTaP levels) of all toxoids and antigens to minimize reactogenicity in adolescents and adults ≥7 years 2
Immunogenicity and Efficacy
After completing the 3-dose primary series, DTaP vaccines demonstrate 1:
- ≥83% of children develop fourfold or greater antibody response to pertussis antigens
- 100% develop protective diphtheria antitoxin titers ≥0.1 IU/mL
- 100% develop protective tetanus antitoxin titers ≥0.01 IU/mL
Large efficacy studies show DTaP provides high and long-lasting protective efficacy against culture-confirmed pertussis, comparable to or exceeding whole-cell pertussis vaccines 3.
Safety Profile
DTaP causes substantially fewer adverse reactions compared to whole-cell DTP 1:
- Significantly lower rates of local reactions (pain, redness, swelling)
- Reduced fever incidence
- Less irritability and persistent crying
- Excellent postmarketing safety record 1
Critical Clinical Considerations
DTaP should NOT be used in persons ≥7 years of age due to increased risk of local reactions; Tdap is the appropriate formulation for this age group 2. However, if DTaP is inadvertently administered to someone ≥7 years, it should count as the Tdap dose 2.
If Tdap is inadvertently given as one of the first 3 infant doses, it should not be counted as valid and must be replaced with DTaP 2.
For children aged 7-10 years who were underimmunized with DTaP, a single dose of Tdap is now recommended to provide catch-up protection 1.