Hib Vaccine (Haemophilus influenzae type b)
Content reviewed against published CDC, AAP, WHO guidelines
Last reviewed:
Key takeaways
- Prevents: Hib meningitis (brain infection), Hib pneumonia
- Schedule: 4 doses starting at 2 months
- Effectiveness: The Hib conjugate vaccine is 95-100% effective at preventing invasive Hib disease after completion of the primary series.
- Most common side effect: Redness or swelling at injection site
How it works
The Hib vaccine is a conjugate vaccine that works by linking a sugar (polysaccharide) from the outer coating of the Haemophilus influenzae type b bacterium to a carrier protein. This conjugation technique is crucial for infants because their immature immune systems cannot mount a strong response to polysaccharides alone. The protein carrier helps the immune system recognize and remember the Hib sugar, producing long-lasting antibody protection.
Recommended schedule
| Dose | Age |
|---|---|
| Dose 1 | 2 months |
| Dose 2 | 4 months |
| Dose 3 | 6 months (PRP-OMP brands only; PRP-T brands skip this dose) |
| Dose 4 | 12-15 months (booster) |
Side effects
Common (mild, resolve in 1-2 days)
- Redness or swelling at injection site (5-30%)
- Mild fever (2-10%)
- Fussiness or irritability
- Decreased appetite
- Drowsiness
Serious (very rare)
- Severe allergic reaction (anaphylaxis) — extremely rare, less than 1 in 1 million doses
- No confirmed serious long-term adverse effects associated with the Hib vaccine
Who should NOT get this vaccine
- Severe allergic reaction (anaphylaxis) to a previous dose of Hib vaccine or any vaccine component
- Age less than 6 weeks (vaccine should not be given before 6 weeks of age)
Effectiveness
The Hib conjugate vaccine is 95-100% effective at preventing invasive Hib disease after completion of the primary series. Since its introduction in the late 1980s, invasive Hib disease in children under 5 has decreased by more than 99% in the United States.
Available brands
ActHIB
Sanofi Pasteur (PRP-T conjugate)
PedvaxHIB
Merck (PRP-OMP conjugate)
Pentacel
Sanofi Pasteur (combination DTaP-IPV/Hib)
Vaxelis
MCM Vaccine Company (hexavalent combination)
Myths vs. facts
Myth: “Hib disease is the same as the flu”
Fact: Despite the confusing name "Haemophilus influenzae," Hib bacteria have nothing to do with influenza (the flu). The bacterium was misnamed in 1892 when it was incorrectly thought to cause influenza. Hib causes meningitis, pneumonia, and bloodstream infections — not the flu.
Myth: “Hib disease was already declining before the vaccine”
Fact: Before the vaccine, Hib was the leading cause of bacterial meningitis in children under 5, causing approximately 20,000 cases of invasive disease per year in the US. Rates dropped more than 99% specifically after the conjugate vaccine was introduced.
Myth: “My breastfed baby is already protected”
Fact: While breastfeeding provides some general immune support, it does not provide reliable specific protection against Hib disease. Studies show that breastfeeding alone is not a substitute for Hib vaccination.
Frequently asked questions
Why are there different numbers of doses depending on the brand?
Does my child still need this vaccine if they are in daycare?
What if my child missed a dose?
Can Hib vaccine be given as part of a combination vaccine?
Sources
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources
Bottom line
The Hib Vaccine (Haemophilus influenzae type b) (Hib) is safe, well-studied, and recommended by the CDC, AAP, and WHO. Talk to your pediatrician if you have questions about timing or your child's specific health needs.
Choosing to vaccinate your child is one of the most important things you can do to protect their health. If you have concerns, your pediatrician is always happy to talk through them with you.