Can Pediarix Be Given for the Third Dose?
Yes, Pediarix can be administered for the third vaccine dose, provided the infant is at least 24 weeks of age (approximately 6 months old) at the time of administration. 1, 2
Critical Age Requirement for Third Dose
The minimum age for the third dose of Pediarix is 24 weeks, which is the minimum age for completion of the hepatitis B vaccine series. 1 This is a crucial distinction from the first two doses, which can be given as early as 6 weeks and 10 weeks respectively. 1
- If the third dose is inadvertently given before 24 weeks of age, an additional hepatitis B vaccine dose must be administered at age ≥24 weeks to complete the hepatitis B series. 1, 3
Standard Dosing Schedule
Pediarix is FDA-approved as a 3-dose series at ages 2,4, and 6 months in infants born to hepatitis B surface antigen (HBsAg)-negative mothers. 2
- The minimum interval between doses 2 and 3 is 4 weeks. 1
- Pediarix can be given as early as 6 weeks of age through 6 years of age (prior to the seventh birthday). 2
Important Limitations
Pediarix should NOT be used for the fourth or fifth DTaP doses (booster doses at 15-18 months and 4-6 years). 1 It is only indicated for the primary 3-dose series. 1, 2
- However, if Pediarix is inadvertently given for a booster dose, the dose does not need to be repeated with another DTaP-containing vaccine when proper spacing of previous doses is maintained. 1
Accelerated Schedule Caveat
Pediarix is NOT recommended for accelerated schedules where the third dose would be given at 4-week intervals (before 24 weeks of age) for early pertussis protection, specifically because of the hepatitis B component's minimum age requirement. 1
Safety Profile
If an extra dose is inadvertently administered, expect increased local reactions (pain, redness, swelling at injection site), which are primarily due to the pertussis component and are typically mild and self-limited. 3 The dose should count as valid in the vaccination series. 3