What are the indications, contraindications, and administration schedules for Vaxelis (hexavalent vaccine), Pediarix (pentavalent vaccine), and Pentacel (pentavalent vaccine) in pediatric patients with various medical histories and previous vaccinations?

Vaccine Selection Guide: Vaxelis vs Pediarix vs Pentacel

When to Use Each Vaccine

Use Pentacel (DTaP-IPV/Hib) for the standard 4-dose infant series at 2,4,6, and 15-18 months when you need DTaP, IPV, and Hib coverage together. 1

Pentacel (DTaP-IPV/Hib)

• Licensed for: 4-dose series in children aged 6 weeks through 4 years 1
• Standard schedule: 2,4,6, and 15-18 months 1, 2
• Components: DTaP + IPV + Hib conjugate 1
• Key advantage: Only combination vaccine FDA-approved for the 4th dose at 15-18 months 2
• Early administration: The 4th dose may be given as early as 12 months if 6 months have elapsed since the 3rd dose and there's concern about missing a vaccination opportunity 1, 2

Pediarix (DTaP-IPV-HepB)

• Licensed for: 3-dose series in infants aged 6 weeks through 6 years 1
• Critical restriction: Only approved for infants born to HBsAg-negative mothers 1
• Standard schedule: 2,4, and 6 months (does NOT include a 4th dose) 1
• Components: DTaP + IPV + Hepatitis B 1
• Key advantage: Combines hepatitis B vaccination with DTaP and IPV, reducing total injections in the first 6 months 1
• Important limitation: Cannot be used for the 15-18 month dose; requires switching to another vaccine 1

Vaxelis (DTaP-HBV-IPV/Hib)

• Licensed for: Primary and booster vaccination from 6 weeks of age 3
• Components: DTaP + Hepatitis B + IPV + Hib (hexavalent) 3, 4
• Key advantage: Most comprehensive single-injection option, covering 6 diseases 3
• Evidence: Demonstrated non-inferiority to comparator vaccines (Infanrix hexa or Pentacel plus Recombivax HB) in clinical trials 3, 4
• Schedule flexibility: Can be used for 3-dose primary series (2,4,6 months) plus booster at 15-18 months 4

Clinical Decision Algorithm

For Standard Infant Immunization Series:

If infant born to HBsAg-negative mother:

• Option 1: Pediarix at 2,4,6 months, then switch to Pentacel or standalone DTaP at 15-18 months 1
• Option 2: Pentacel at 2,4,6,15-18 months + separate HepB vaccine 1
• Option 3: Vaxelis at 2,4,6,15-18 months (covers all antigens in single injection) 3, 4

If infant born to HBsAg-positive mother:

• Do NOT use Pediarix (contraindicated) 1
• Use Pentacel + separate HepB vaccine OR Vaxelis 1, 3

For Accelerated Schedules:

• Minimum 4-week intervals between doses 1-3 1
• Third dose must not be given before 14 weeks of age 1
• When Pentacel is given at 2,4,6, and 12-18 months with proper spacing, this provides 4 valid IPV doses 1, 2

For American Indian/Alaska Native Populations:

• Avoid Pentacel for the first Hib dose in communities with ongoing Hib transmission 1
• PRP-OMP-containing vaccines (not Pentacel's Hib-TT) provide more rapid seroconversion in first 6 months 1
• Consider stocking only PRP-OMP vaccines in clinics serving predominantly AI/AN children 1

Contraindications

Absolute Contraindications (All Three Vaccines):

• Severe allergic reaction (anaphylaxis) to any vaccine component 1
• Encephalopathy within 7 days of previous pertussis-containing vaccine dose not attributable to another cause 1

Pediarix-Specific Contraindication:

• Infant born to HBsAg-positive mother (this is unique to Pediarix) 1

Precautions (Defer Vaccination):

• Progressive neurologic disorder, including infantile spasms, uncontrolled epilepsy, or progressive encephalopathy 1
• Guillain-Barré syndrome within 6 weeks of previous tetanus toxoid-containing vaccine 1
• Moderate or severe acute illness 1

Common Pitfalls to Avoid

Pitfall 1: Using Pediarix for all 4 infant doses

• Pediarix is only licensed for 3 doses (2,4,6 months); you must switch vaccines for the 15-18 month dose 1

Pitfall 2: Using Pediarix in infants of HBsAg-positive mothers

• This is an absolute contraindication; use Pentacel or Vaxelis with separate HepB instead 1

Pitfall 3: Refusing to count inadvertently administered doses

• If Pentacel is given after age 5 years, count it as valid 1
• If Kinrix is inadvertently given for the 4th dose, count it as valid if minimum intervals are met 2

Pitfall 4: Restarting series when switching manufacturers

• Whenever feasible, use the same manufacturer's DTaP, but vaccination should not be deferred if the brand is unavailable or unknown 1
• Do not restart the series; continue with available vaccine 1

Pitfall 5: Missing the 4th dose timing window

• The 4th dose can be given as early as 12 months (not just 15 months) if 6 months have elapsed since dose 3 and there's concern about missing the opportunity 1, 2

Interchangeability Considerations

• Data on interchanging DTaP vaccines from different manufacturers are limited 1
• Same manufacturer's product is preferred throughout the series when feasible 1
• However, never defer vaccination if the specific brand previously used is unavailable or unknown 1, 2
• All three vaccines have similar safety profiles and antibody responses compared to separately administered components 1