Pharmacology · Bacterial and antimalarial vaccines
Haemophilus influenzae type b (Hib) vaccine !
Conjugate vaccine: Hib capsular polysaccharide linked to a protein. It nearly eliminated Hib meningitis and epiglottitis in young children.
Updated 2026-11-01
Also called: Hib conjugate vaccine, Conjugated PRP, Component of pentavalent and hexavalent vaccines
Mechanism of action
The Hib capsule is polyribosyl-ribitol-phosphate (PRP). As a plain polysaccharide it gives a T-independent response, poor under two years of age. Linked to a carrier protein (tetanus toxoid, CRM197 or another), it becomes T-dependent: infants form opsonising antibodies and memory, and each dose boosts the response.
- Capsular PRP is linked to a carrier protein
- T cells help B cells make anti-PRP antibodies
- Antibodies opsonise the bacterium and activate complement
- Memory forms and nasopharyngeal carriage falls
Pharmacokinetics
- Onset and duration
- Protection is reached with the infant series; repeat doses boost the response
Indications
- Prevention of invasive Hib disease (meningitis, epiglottitis, pneumonia, bacteraemia) in infants and young children Bacterial meningitis →
Adverse effects
Common
- Local pain, redness or swelling
- Fever and irritability
Contraindications
- Age under six weeks (risk of immunological tolerance)
- Previous anaphylaxis to a dose or component
Key interactions
- Combination vaccines (DTP, hepatitis B, polio)
- Given within pentavalent or hexavalent vaccines; the carrier protein does not replace tetanus or diphtheria vaccination
What is monitored
- Minimum age at the start of the series
- Local reaction and fever after the dose
Administration and safety
- Intramuscular route
- Usually given in combination vaccines: check which antigens the product contains to avoid duplicate doses
- Respect the minimum starting age
Nursing care
- Check age and vaccination card before giving
- Watch for fever and local reaction
- Explain to carers why the series must be completed
Pregnancy and breastfeeding
Not part of routine vaccination in pregnancy; it is used in infants and in risk groups.
Test yourself
Think of the answer, then tap the question to see it.
What antigen does Hib vaccine contain?
The capsular polysaccharide polyribosyl-ribitol-phosphate (PRP), linked to a carrier protein.
Why is Hib vaccine not given before six weeks of age?
Because it may induce immunological tolerance and reduce the response to later doses.
Which serious airway complication of Hib became rare with vaccination?
Epiglottitis, which can obstruct the airway and threaten life.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Chapter 8: Haemophilus influenzae | Pink Book | CDC (Centers for Disease Control and Prevention, 2021); Meningitis (World Health Organization, 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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