Pneumococcal polysaccharide serotype 31 conjugated to CRM197

Table of contents

• What is pneumococcal polysaccharide serotype 31 conjugated to CRM197?
• How does pneumococcal polysaccharide serotype 31 conjugated to CRM197 work?
• Which conditions is it used or studied for?
• How is pneumococcal polysaccharide serotype 31 conjugated to CRM197 given?
• What do the clinical trials show?
• What side effects are known?

What is pneumococcal polysaccharide serotype 31 conjugated to CRM197?

Pneumococcal polysaccharide serotype 31 conjugated to CRM197 is one of 21 pneumococcal polysaccharide components that make up the 21-valent pneumococcal conjugate vaccine marketed as CAPVAXIVE.^[2] The full registry name lists 21 serotypes, each conjugated to the carrier protein CRM197, including serotype 31.^[2] The vaccine is authorised as a medicine in the European Union under authorisation record EU/1/25/1913/001, held by Merck Sharp & Dohme B.V.^[2] The therapeutic area covers bacterial infections and mycoses, immune system processes, and immune system diseases.^[2]

How does pneumococcal polysaccharide serotype 31 conjugated to CRM197 work?

As a conjugate vaccine component, the pneumococcal polysaccharide from serotype 31 is chemically linked to the carrier protein CRM197. This conjugation is designed to help the immune system recognise the polysaccharide and produce antibodies against it. The related 20-valent conjugate vaccine Apexxnar, which also contains pneumococcal polysaccharides conjugated to a carrier protein, is described by the European Medicines Agency as eliciting an immune response to all serotypes contained in the product.^[3] The benefit of such vaccines is presumed protection against pneumococcal disease, based on immunobridging data.^[3]

Which conditions is it used or studied for?

The registered trials investigate the vaccine containing this substance in two specific populations:

• Asplenia — people who have had their spleen removed (splenectomy) or lack a functioning spleen, who are at increased risk of severe pneumococcal infection.^[1]
• Medium or high risk for pneumococcal invasive infection — adults with conditions that put them at greater risk of serious pneumococcal disease.^[2]

In the European Union, the related 20-valent conjugate vaccine Apexxnar is indicated for active immunisation for the prevention of invasive disease and pneumonia caused by Streptococcus pneumoniae in individuals 18 years of age and older.^[3]

How is pneumococcal polysaccharide serotype 31 conjugated to CRM197 given?

The vaccine containing this substance, CAPVAXIVE, is a solution for injection in a pre-filled syringe, given by intramuscular injection.^[2] In the registered trials, the dose used is 0.5 ml.^[1][2] The product is described as a pneumococcal polysaccharide conjugate vaccine (21-valent).^[2]

What do the clinical trials show?

Two Phase 3 interventional clinical trials are registered for the vaccine containing this substance. Both are currently authorised, meaning they have received regulatory approval to proceed.

The first trial (2024-515363-63-00) includes 70 participants with asplenia. It measures the mean fold change of serotype-specific IgG antibodies against serotypes common to both PCV20 and PCV21, 2–3 weeks after a booster vaccination with PCV21, given at least 12 months after primary vaccination with PCV20.^[1] The goal is to assess how spleen removal affects the induction of immunological memory after primary vaccination with PCV20.^[1]

The second trial (NCT06822907) includes 1,160 participants at medium or high risk for pneumococcal invasive infection. It measures the proportion of immune "good responders" at 1 month after vaccination, defined by seroconversion (a 2-fold or 4-fold increase in vaccine-type IgG) for at least 10 of 13 vaccine serotypes tested, together with an immune protective response.^[2] The aim is to demonstrate that the immune response when the vaccine is given during an acute febrile illness is non-inferior to the response when given 15–58 days after recovery.^[2]

In both trials, the comparison product is Prevenar 20, a 20-valent pneumococcal polysaccharide conjugate vaccine.^[1][2]

What side effects are known?

For the related 20-valent pneumococcal conjugate vaccine Apexxnar, the most common side effects reported are injection site pain, fatigue and headache.^[3] No side effect data specific to CAPVAXIVE or to serotype 31 conjugated to CRM197 were provided in the sources for this page.