Protective Efficacy of DTaP Vaccine by Dose

Pertussis Protection by Dose

A 3-dose primary series of DTaP administered at ages 2, 4, and 6 months provides vaccine efficacy estimates ranging from 79% to 89% against culture-confirmed pertussis disease, with protection lasting up to 2 years after the third dose 1
The complete 5-dose DTaP series has an estimated overall effectiveness of 88.7% (95% CI = 79.4%–93.8%) against pertussis 1
Within the first year after receiving the fifth DTaP dose, vaccine effectiveness reaches its peak at 98.1% (95% CI = 96.1%–99.1%) 1
Protection wanes over time, with effectiveness declining to approximately 71.2% (95% CI = 45.8%–84.8%) by ≥5 years after the fifth dose 1

After receiving 3 doses of diphtheria toxoid-containing vaccines, virtually all infants develop protective diphtheria antitoxin titers >0.01 IU/mL 3
A diphtheria antitoxin level of 0.01 to 0.09 IU/mL provides some degree of protection, whereas levels ≥0.1 IU/mL are considered fully protective 3
Levels >1.0 IU/mL are associated with long-lasting protection against diphtheria 3
After the primary vaccination series, protection lasts for approximately 3-5 years, requiring booster doses to maintain immunity 3

One dose of tetanus toxoid vaccine provides little to no immunity 4
After receiving 3 doses of tetanus toxoid-containing vaccine, virtually all infants and adults develop protective tetanus antitoxin titers >0.1 IU/mL 4
A primary immunization series with 3 doses of tetanus toxoid induces a mean antitetanus level of 0.2 IU/mL, providing protection from tetanus for approximately 3-5 years 4
Additional booster doses significantly heighten the immune response and prolong the duration of protective immunity 4
Booster doses at age 4-8 years and during adolescence provide long-lasting protective immunity with protection lasting 20-30 years from the last dose 4

After 4 doses of Daptacel (Sanofi Pasteur), 98.5% of children achieve diphtheria antitoxin levels of ≥1.0 IU/mL, and 100% achieve tetanus antitoxin levels of ≥1.0 IU/mL 2
The fifth dose at age 4-6 years is expected to produce a robust immune response in children previously primed with the same vaccine 1

Multiple studies support the findings of a progressive decrease in DTaP vaccine effectiveness and increased risk for pertussis over time after receipt of the fifth dose 1
The safety profile of DTaP vaccines is well-established, with significantly fewer adverse events compared to whole-cell pertussis vaccines 1