At what age is the first dose of Tetanus, diphtheria, and pertussis (Tdap) vaccine typically administered to infants?

Tdap Vaccine: First Dose Timing

Critical Distinction: Tdap vs. DTaP

Tdap is NOT given to infants—the first dose of tetanus-containing vaccine for infants is DTaP, administered at 2 months of age. 1

Tdap is the adolescent/adult formulation and is only licensed for persons aged ≥10 years (Boostrix) or ≥11 years (Adacel). 2

DTaP Vaccination Schedule for Infants and Children

The routine childhood vaccination series uses DTaP (diphtheria, tetanus, and acellular pertussis vaccine), not Tdap:

Standard Five-Dose Series

• First dose: 2 months of age 1, 2
• Second dose: 4 months of age 1, 2
• Third dose: 6 months of age 1, 2
• Fourth dose: 15-18 months of age 1, 2
• Fifth dose: 4-6 years of age 1, 2

Minimum Age and Intervals

• The earliest DTaP can be administered is 6 weeks of age 1, 3
• Minimum interval between first and second doses: 4 weeks 1
• The fourth dose requires at least 6 months after the third dose and cannot be given before 12 months of age 1, 2

Tdap Vaccination for Adolescents and Adults

Tdap is first administered at 11-12 years of age as a single booster dose for adolescents who completed the childhood DTaP series. 2

Key Populations for Tdap

• Adolescents aged 11-18 years: Single dose at age 11-12 years, preferably 2
• Adults ≥19 years: Single dose to replace one Td booster, regardless of interval since last tetanus-containing vaccine 2
• Pregnant women: One dose during EACH pregnancy between 27-36 weeks gestation, regardless of prior Tdap history 2, 4

Common Clinical Pitfalls

Do not confuse DTaP with Tdap—using the wrong formulation for age is the most common error. 5 DTaP contains higher diphtheria toxoid content appropriate for children, while Tdap has reduced diphtheria and pertussis antigens for adolescents and adults. 2

Never administer Tdap to children under 10 years of age—it is not licensed or indicated for this population and provides inadequate diphtheria protection. 2, 5

DTaP should not be given to persons ≥7 years—the higher diphtheria content causes increased adverse reactions in older individuals. 2, 5