Main decision tree
Hib: routine child or asplenia?
At a glance
- Routine: doses at 2, 4 and 6 months plus a booster at 12–15 months; with PedvaxHIB (PRP-OMP), only 2 and 4 months plus the booster.
- The fewer doses needed the older the child: first dose at 12–14 months means 2 doses; at 15–59 months, just 1.
- A dose given at 15 months or older completes the series for a healthy child.
- Healthy children 5 years and older who never had Hib need none.
- Asplenia, sickle cell disease, HIV, immunoglobulin or early complement deficiency and chemotherapy change the rules up to 59 months.
- After a stem cell transplant, give 3 doses again, whatever was given before.
- Minimum age is 6 weeks; never give Hib before 6 weeks, as it can blunt later responses.
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Routine childhood vaccine schedule (AAP 2026) — schedule graph
Routine schedule
| Product | Primary doses | Booster |
|---|---|---|
| PedvaxHIB (PRP-OMP) | 2 and 4 months | 12–15 months |
| ActHIB, Hiberix, Pentacel (PRP-T) | 2, 4 and 6 months | 12–15 months |
| Mixed or unknown products | 3 doses (2, 4 and 6 months) | 12–15 months |
Catch-up rules
- Minimum age is 6 weeks; doses before 12 months are at least 4 weeks apart.
- First dose at 7–11 months: 3 doses in total, the last at 12–15 months and 8 weeks after the previous one.
- First dose at 12–14 months: 2 doses, 8 weeks apart.
- First dose at 15–59 months: 1 dose only.
- Any dose at 15 months or older completes the series for a healthy child.
- Healthy children 5 years and older need no Hib, even if never vaccinated.
Children at higher risk
- 12–59 months with asplenia, sickle cell disease, HIV, immunoglobulin or early complement deficiency, or chemotherapy: 2 doses 8 weeks apart if unvaccinated or only 1 dose before 12 months; 1 dose if 2 or more doses before 12 months.
- Unvaccinated children 5–18 years with asplenia, sickle cell disease or HIV: 1 dose.
- Planned splenectomy: give Hib at least 14 days before surgery when possible.
- Stem cell transplant: 3 doses 4 weeks apart, starting 6–12 months after transplant, whatever the history.
- Chemotherapy or radiation: repeat doses given during treatment or within 14 days before it, at least 3 months after treatment ends.
Who should not get it, and side effects
- Do not give after anaphylaxis to a previous dose or a vaccine component.
- Do not give before 6 weeks of age.
- A moderate or severe acute illness is a reason to delay; a mild cold is not.
- Common: redness, swelling and pain at the site and mild fever for a day or two.
Common questions
How many Hib doses does a baby need?
Four with ActHIB, Hiberix or Pentacel (2, 4, 6 and 12–15 months), or three with PedvaxHIB (2, 4 and 12–15 months).
Does an unvaccinated 2-year-old need the full Hib series?
No. A healthy child who gets a first Hib dose at 15–59 months needs only that one dose.
Does a 5-year-old who never had Hib need it?
Not if healthy: Hib is not given to healthy children 5 years and older. Children with asplenia, sickle cell disease or HIV who are unvaccinated get 1 dose.
Why does PedvaxHIB need fewer doses?
Its PRP-OMP conjugate makes protective antibodies after the first dose, so 2 primary doses are enough. If the products are mixed or unknown, give 3 primary doses.
Does a child with sickle cell disease need extra Hib boosters?
No routine extra boosters if the series is complete. The extra doses apply only when the child was behind at 12–59 months, or unvaccinated at 5 years or older.
Sources
- CDC: Child and adolescent immunization schedule and catch-up guidance
- CDC: Child and adolescent schedule notes (Hib vaccination)
- CDC: Hib vaccine recommendations
- AAP: Immunization schedule (aap.org)
Written for Pedemy in our own words from the sources above; checked October 2026. For education only, not medical advice. Pedemy is independent and not affiliated with or endorsed by the organizations cited.