What are the guidelines for a 5th dose of Diphtheria, Tetanus, and Pertussis (DTaP) vaccine?

Guidelines for the 5th Dose of DTaP Vaccine

The fifth (second booster) dose of DTaP should be administered to children aged 4-6 years to confer continued protection against disease during the early years of schooling, but a fifth DTaP dose is not necessary if the fourth DTaP dose in the series is administered at age ≥4 years. 1

Standard DTaP Vaccination Schedule

The Advisory Committee on Immunization Practices (ACIP) recommends a 5-dose series of DTaP vaccine for children, administered as follows:

• Primary series: Three doses at ages 2,4, and 6 months
• First booster: Fourth dose at 15-18 months of age
• Second booster: Fifth dose at 4-6 years of age 1

Key Guidelines for the 5th Dose

When the 5th Dose Is Required:

• Children who received their fourth DTaP dose before their 4th birthday should receive the fifth dose between ages 4-6 years 1
• The fifth dose provides continued protection during early school years when exposure risk increases

When the 5th Dose Is NOT Required:

• If the fourth DTaP dose was administered at age 4 years or older, the fifth dose is not necessary 1, 2
• This exception recognizes that adequate immunity is maintained when the fourth dose is given at or after age 4

Important Timing Considerations

• The minimum age for the fifth dose is 4 years 1
• There should be at least 6 months between the fourth and fifth doses 1
• No more than 6 doses of diphtheria and tetanus toxoid-containing vaccines should be administered before age 7 due to increased risk of adverse reactions 2

Clinical Rationale for the 5th Dose

The fifth dose is crucial for maintaining immunity because:

• Antibody levels to pertussis antigens wane significantly before the 4-6 year booster 3
• Studies show that before the 4-6 year booster, many children have diphtheria antibody titers below the level associated with certain, durable protection 3
• Research indicates that for every additional year after the last dose of DTaP, the odds of pertussis increased by 1.33 times 4
• Without a booster dose, the effectiveness of 3 doses wanes more rapidly from 2 to 4 years of age 5

Special Considerations

Accelerated Schedule:

• For children who started on an accelerated schedule (beginning as early as 6 weeks of age), the fifth dose should still not be administered before the child is aged 4 years 1

Interchangeable Products:

• While using the same DTaP product for all doses is preferable, any licensed DTaP vaccine may be used to complete the vaccination series if the previously used product is unknown or unavailable 1
• Studies show that mixing DTaP products increases with the number of doses administered, with approximately 39% of children receiving a mixed series by the time they complete all 5 doses 6

After Completing the DTaP Series:

• After completing the 5-dose DTaP series, adolescents should receive a single dose of Tdap at age 11-12 years 1
• If DTaP is inadvertently administered to a fully vaccinated child aged 7-10 years, this dose should be counted as the adolescent Tdap dose 1

By following these guidelines, healthcare providers can ensure optimal protection against diphtheria, tetanus, and pertussis while minimizing unnecessary vaccination.