In short
Pneumococcal polysaccharide serotype 20A conjugated to CRM197 is one of 21 bacterial sugar components in the authorised vaccine CAPVAXIVE, a pneumococcal polysaccharide conjugate vaccine (21-valent). It is studied in two authorised Phase 3 trials with a total of 1,230 planned participants: one in people without a spleen (asplenia) and one in adults with fever who are at medium or high risk for pneumococcal infection.
Key points
- Pneumococcal polysaccharide serotype 20A is one component of the 21-valent vaccine CAPVAXIVE, authorised in the EU.
- Two Phase 3 trials are authorised, with 70 and 1,160 planned participants respectively.
- One trial studies the vaccine response in people without a spleen, vaccinated before or after spleen removal.
- The other trial studies vaccination during acute febrile illness in adults at medium or high risk for pneumococcal infection.
- Both trials compare CAPVAXIVE (21-valent) with Prevenar 20 (20-valent), given as an intramuscular injection.
- The main measure in both trials is the antibody response against pneumococcal serotypes after vaccination.
What is pneumococcal polysaccharide serotype 20A?
Pneumococcal polysaccharide serotype 20A conjugated to CRM197 is one of 21 pneumococcal polysaccharide components in the vaccine CAPVAXIVE, a pneumococcal polysaccharide conjugate vaccine (21-valent). The full registry name lists 21 serotypes, including serotype 20A, each conjugated to CRM197, a carrier protein derived from a non-toxic mutant of diphtheria toxin. CAPVAXIVE is authorised as a medicine in the European Union, with the authorisation record EU/1/25/1913/001 held by Merck Sharp & Dohme B.V. The vaccine is also known as pneumococcal polysaccharide conjugate vaccine (21-valent). A related 20-valent vaccine, Apexxnar, received a positive opinion from the European Medicines Agency (EMA) in December 2021 for prevention of pneumococcal pneumonia and associated invasive disease in adults aged 18 and older.
How does pneumococcal polysaccharide serotype 20A work?
Pneumococcal polysaccharide serotype 20A is a sugar molecule from the surface of the bacterium Streptococcus pneumoniae. In a conjugate vaccine, the polysaccharide is chemically linked to the CRM197 carrier protein. This linkage helps the immune system recognise the sugar and produce antibodies against it, which is the basis for protection against pneumococcal disease caused by that serotype. The 20-valent vaccine Apexxnar elicits an immune response to all 20 serotypes contained in the product, and its benefit is the presumed protection against pneumococcal disease based on immunobridging data.
Which conditions is it used or studied for?
The therapeutic area for this substance covers bacterial infections and mycoses, immune system processes, and immune system diseases. The authorised trials study two specific situations:
- Asplenia — the absence of a spleen. The trial investigates vaccine response in patients without a spleen, vaccinated before or after spleen removal.
- Medium or high risk for pneumococcal invasive infection — the trial studies vaccination during an acute febrile illness in adults at medium or high risk for pneumococcal infections.
The authorised indication for the related 20-valent vaccine Apexxnar is active immunisation for the prevention of invasive disease and pneumonia caused by Streptococcus pneumoniae in individuals 18 years of age and older.
How is pneumococcal polysaccharide serotype 20A given?
The pharmaceutical form is a solution for injection, and the route of administration is intramuscular injection. CAPVAXIVE is supplied as a solution for injection in a pre-filled syringe, with a 0.5 ml dose given as an intramuscular injection. The related 20-valent vaccine Apexxnar is available as a suspension for injection.
What do the clinical trials show?
Two authorised Phase 3 interventional trials investigate CAPVAXIVE, the 21-valent vaccine containing serotype 20A. Both trials compare CAPVAXIVE with Prevenar 20, a 20-valent pneumococcal polysaccharide conjugate vaccine, given as a 0.5 ml intramuscular injection.
The first trial, 2024-515363-63-00, has 70 planned participants with asplenia. Its primary outcome is the mean fold change of pneumococcal serotype-specific IgG antibodies against serotypes common to PCV20 and PCV21, measured 2–3 weeks after booster vaccination with PCV21, at least 12 months after primary vaccination with PCV20 in asplenic patients primed before or after splenectomy. The trial aims to assess the impact of splenectomy on the induction of immunological memory after primary vaccination with PCV20, measured as the serological response three weeks after booster vaccination with PCV21.
The second trial, NCT06822907, has 1,160 planned participants who are at medium or high risk for pneumococcal invasive infection. Its primary outcome is the proportion of immune "good responders" to PCV-20 or PCV-21 at one month after vaccination in both arms. A good responder is defined by seroconversion (a 2-fold or 4-fold increase in vaccine-type IgG) for at least 10 of 13 tested serotypes, and an immune protective response defined as ELISA IgG of at least 1.3 μg/mL in at least 10 of 13 tested serotypes. The trial aims to demonstrate that the immune response at one month after vaccination during an acute febrile illness is non-inferior to the immune response obtained at one month after vaccination given 15–58 days after resolution of the febrile illness.
Both trials measure antibody responses against pneumococcal serotypes as their main outcome, and both are currently in the authorised status, meaning they have been approved to start but may not yet be recruiting participants.
What side effects are known?
For the related 20-valent vaccine Apexxnar, the most common side effects are injection site pain, fatigue and headache. No side effect information specific to the 21-valent vaccine CAPVAXIVE is provided in the available sources.