Pharmacology · Bacterial and antimalarial vaccines
Pneumococcal vaccine !
Conjugate (for infants and adults) or polysaccharide vaccines against the pneumococcal serotypes that most often cause pneumonia, meningitis and bacteraemia.
Updated 2026-11-01
Also called: Pneumococcal conjugate vaccine (PCV), Pneumococcal polysaccharide vaccine (PPSV)
Mechanism of action
Protection is serotype-specific: each vaccine contains the capsular polysaccharides of a set of serotypes. The polysaccharide vaccine induces a T-independent response, with no memory and poor in young children. The conjugate vaccine, with polysaccharides linked to a carrier protein, is T-dependent, works in infants and reduces carriage.
- Vaccine supplies capsular polysaccharides from several serotypes
- Protein-conjugated: T-dependent response with memory
- Antibodies opsonise pneumococci for phagocytosis
- Fewer carriers: unvaccinated people are protected too
Pharmacokinetics
- Onset and duration
- Protection follows the series; polysaccharide vaccine gives no booster response when repeated
Indications
- Prevention of pneumococcal pneumonia in infants, older adults and risk groups Community-acquired pneumonia →
- Prevention of pneumococcal meningitis and bacteraemia Bacterial meningitis →
- Functional or anatomical asplenia, especially in sickle cell disease Sickle cell disease →
Adverse effects
Common
- Local pain, swelling or induration
- Fever, irritability, fatigue, headache and muscle pain
Contraindications
- Previous anaphylaxis to a component or a dose
- Precaution: moderate or severe acute illness
Key interactions
- Inactivated influenza vaccine
- Given together, they were linked to more febrile seizures in young children during some seasons
What is monitored
- Risk conditions: asplenia, sickle cell disease, cochlear implant, CSF leak, immunosuppression
- Which vaccine was given before (conjugate or polysaccharide)
Administration and safety
- Intramuscular route
- Distinguish conjugate from polysaccharide vaccine: they are not interchangeable and have different indications
- Record the product given to plan the sequence
Nursing care
- Identify risk conditions that justify the vaccine in adults
- Watch for fever in children, especially if other vaccines were given the same day
- Teach the signs of pneumonia and meningitis that need care
Pregnancy and breastfeeding
Not part of routine vaccination in pregnancy.
Test yourself
Think of the answer, then tap the question to see it.
Why does the polysaccharide vaccine work poorly in infants?
It induces a T-independent response, weak under two years of age and without memory; infants therefore receive the conjugate vaccine.
What is serotype replacement?
A rise in disease from serotypes not in the vaccine after vaccine serotypes decline; it happened with serotype 19A after the first conjugate vaccine.
Which patients with sickle cell disease are at high pneumococcal risk, and why?
All of them, because of functional asplenia: without an effective spleen, encapsulated bacteria are poorly cleared.
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 17: Pneumococcal Disease | 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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