In short
Pneumococcal polysaccharide serotype 9V is one of ten polysaccharide components in Synflorix, an authorised pneumococcal conjugate vaccine. The serotype 9V polysaccharide is conjugated to a protein D carrier derived from non-typeable Haemophilus influenzae and adsorbed on aluminium phosphate. A completed Phase 2 trial in 100 healthy toddlers assessed the safety and immunogenicity of a monovalent pneumococcal conjugate candidate that included this component, administered as a 2-dose series.
Key points
- Authorised medicine: the serotype 9V component is part of Synflorix, a pneumococcal conjugate vaccine authorised in the EU.
- One completed Phase 2 trial in 100 healthy toddlers aged 11 to 15 months studied a pneumococcal conjugate candidate.
- Condition studied: prevention of pneumococcal infections caused by Streptococcus pneumoniae.
- Route: given as a 0.5 ml suspension for injection by intramuscular use.
- What was measured: local reactions, systemic events, adverse events and serious adverse events.
What is pneumococcal polysaccharide serotype 9V?
Pneumococcal polysaccharide serotype 9V conjugated to protein D (derived from non-typeable Haemophilus influenzae) carrier protein adsorbed on aluminium phosphate is a bacterial polysaccharide component of a pneumococcal conjugate vaccine. One 0.5 ml dose of Synflorix contains 1 microgram of the serotype 9V polysaccharide, conjugated to 9–16 micrograms of protein D carrier and adsorbed on aluminium phosphate. The substance is part of Synflorix, a vaccine authorised in the European Union under marketing authorisation numbers EU/1/09/508/002 through EU/1/09/508/005, held by GlaxoSmithKline Biologicals S.A. Serotype 9V is one of ten pneumococcal serotypes included in this authorised vaccine.
How does pneumococcal polysaccharide serotype 9V work?
Pneumococcal conjugate vaccines link a bacterial polysaccharide to a carrier protein to strengthen the immune response. In Synflorix, the serotype 9V polysaccharide is conjugated to protein D, a carrier derived from non-typeable Haemophilus influenzae. The conjugate helps the immune system recognise the polysaccharide and generate antibodies against Streptococcus pneumoniae bacteria expressing serotype 9V. Pneumococcal serotypes differ in their potential for colonisation, invasiveness and virulence; serotypes with low invasive potential can still be associated with high case-fatality rates once they become invasive.
Which conditions is it used or studied for?
- Pneumococcal infections — infections caused by Streptococcus pneumoniae, including invasive pneumococcal disease such as bloodstream infection and meningitis, as well as pneumonia.
- Prevention of disease caused by Streptococcus pneumoniae — the indication for pneumococcal conjugate vaccines in paediatric investigation plans.
How is pneumococcal polysaccharide serotype 9V given?
The substance is formulated as a suspension for injection, given by intramuscular use. Synflorix is available in 0.5 ml pre-filled syringes and vials, including multidose vials of 2.0 ml. In the Phase 2 trial, a monovalent pneumococcal conjugate candidate containing serotype 9V was administered as a 0.5 ml intramuscular injection in a 2-dose series.
What do the clinical trials show?
One completed Phase 2 trial (EU CT number 2023-505154-18-00) evaluated a monovalent pneumococcal conjugate candidate in 100 healthy toddlers aged 11 to 15 months. The study compared the candidate against Synflorix and other pneumococcal conjugate components, including a serotype 3 conjugate adsorbed on aluminium phosphate and PF-07831695. The primary outcomes were prompted local reactions at the injection site (redness, swelling and pain), prompted systemic events (fever, decreased appetite, drowsiness/increased sleep and irritability), adverse events and serious adverse events. The trial was interventional and has been completed.
What side effects are known?
The Phase 2 trial measured injection-site reactions and systemic events as primary outcomes, including redness, swelling, pain, fever, decreased appetite, drowsiness and irritability. These are the reactions the study set out to record; the registry record does not report the frequency of each reaction. No other side-effect data are provided in the sources for this page.