Pneumococcal polysaccharide serotype 6A

Table of contents

• What is pneumococcal polysaccharide serotype 6A?
• How does pneumococcal polysaccharide serotype 6A work?
• Which conditions is it used or studied for?
• How is pneumococcal polysaccharide serotype 6A given?
• What do the clinical trials show?
• What side effects are known?

What is pneumococcal polysaccharide serotype 6A?

Pneumococcal polysaccharide serotype 6A is one of the sugar molecules from the outer coating of the bacterium Streptococcus pneumoniae, which causes pneumonia, meningitis and bloodstream infections.^[3] In vaccines, this sugar is chemically linked (conjugated) to a carrier protein called CRM197, a non-toxic variant of diphtheria toxin, to make it more effective at triggering an immune response.^[3]

The substance appears as a component of authorised pneumococcal conjugate vaccines, including Vaxneuvance (15-valent) and PREVNAR 20 (20-valent), and is also part of the investigational 21-valent vaccine known as CAPVAXIVE.^[3] In the EU clinical trials register, the substance is listed as authorised as a medicine, with marketing authorisation records held by Sanofi Pasteur Inc. and Merck Sharp & Dohme B.V.^[1][2]

How does pneumococcal polysaccharide serotype 6A work?

When the serotype 6A polysaccharide is conjugated to CRM197 and injected, the immune system recognises the sugar as foreign and produces antibodies (immunoglobulin G, IgG) specifically against it.^[1] These antibodies help the body destroy pneumococcal bacteria carrying the 6A sugar coating if encountered later, reducing the risk of disease.^[3] The immune response can be measured as the concentration of serotype-specific IgG in the blood, and as opsonophagocytic activity (OPA), which reflects how well the antibodies help immune cells engulf and kill the bacteria.^[2]

Which conditions is it used or studied for?

• Pneumococcal immunisation — the trials investigate vaccination to protect healthy infants, toddlers, children and adolescents against disease caused by Streptococcus pneumoniae.^[1][2]
• Prevention of pneumococcal disease — the paediatric investigation plan describes prevention of disease caused by Streptococcus pneumoniae as the indication.^[3]

How is pneumococcal polysaccharide serotype 6A given?

The vaccines containing this substance are given as a suspension for injection in a pre-filled syringe, administered by intramuscular injection.^[3] The dose in the trials is 0.5 ml per injection.^[1][2] A paediatric formulation is available in three product records.^[1]

What do the clinical trials show?

Two authorised Phase 3 trials are registered in the EU Clinical Trials Information System. Both investigate a 21-valent pneumococcal conjugate vaccine (PCV21) that includes serotype 6A, in healthy infants, toddlers, children and adolescents.^[1][2]

The first trial (2023-507600-32-00) enrols 1,113 healthy infants from approximately 2 months of age and compares PCV21 against Vaxneuvance (15-valent).^[1] Its main goal is to show that the antibody response to PCV21 is at least as good as the response to Vaxneuvance for the shared serotypes, and better for the six serotypes unique to PCV21, measured 30 days after the toddler dose.^[1]

The second trial (2024-512271-13-00) enrols 1,402 participants aged from 7 months to 17 years and compares PCV21 against PREVNAR 20 (20-valent).^[2] It measures safety outcomes — including immediate adverse events, solicited injection site and systemic reactions, and serious adverse events — as well as serotype-specific IgG concentrations and OPA titers for all serotypes in PCV21.^[2]

Both trials are currently authorised, meaning they have received regulatory approval to proceed but are not yet reporting results.^[1][2]

What side effects are known?

The clinical trial records list the safety outcomes being measured, including solicited injection site reactions (such as redness, swelling or pain), solicited systemic reactions (such as fever or irritability), unsolicited adverse events, and serious adverse events.^[2] However, no supplementary sources in this dataset report the actual side effect profile of vaccines containing pneumococcal polysaccharide serotype 6A, so no specific side effect frequencies are described here.