Booster and Catch‑Up Use of Pediarix

Booster Dose Considerations

In children who inadvertently receive Pediarix as a booster dose (i.e., after the primary 3‑dose series) and the recommended spacing between doses is maintained, the administered dose is considered valid and does not need to be repeated. This recommendation is based on CDC guidance. [1][2]

Pediarix may be employed for catch‑up vaccination in children younger than 5 years who are behind schedule for the DTaP‑IPV‑HepB series, provided the vaccine is used according to the catch‑up algorithm. This practice is endorsed by the CDC. [2][3]
When using Pediarix for catch‑up, the minimum interval requirements between doses (e.g., at least 4 weeks between the first and second dose, and at least 6 months between the second and third dose) must still be observed to ensure adequate immunogenicity. This interval guidance is outlined by the CDC. 3