In short
N. meningitidis group Y polysaccharide is a sugar molecule from the surface of Neisseria meningitidis bacteria, used as part of vaccines to protect against meningococcal disease. It is a component in authorised vaccines such as Nimenrix and MenFive, where it is conjugated (linked) to a carrier protein to improve immune responses.
Key points
- N. meningitidis group Y polysaccharide is a bacterial surface sugar used in meningococcal vaccines.
- It is included in authorised vaccines such as Nimenrix and MenFive.
- The substance is given as an intramuscular injection in a 0.5 ml dose.
- The registry data includes a Phase 2 trial with 45 participants.
- The trial measures safety and tolerability as its primary outcome.
- Vaccines containing this polysaccharide protect against meningococcal group Y disease.
What is N. meningitidis group Y polysaccharide?
N. meningitidis group Y polysaccharide is a long chain of sugar molecules (a polysaccharide) that forms part of the outer capsule of Neisseria meningitidis bacteria belonging to serogroup Y. The full name is N. meningitidis group Y polysaccharide. The capsule is a major virulence factor — it helps the bacteria evade the immune system and cause invasive disease.
In vaccines, this polysaccharide is not used on its own. It is conjugated (chemically linked) to a carrier protein such as tetanus toxoid or CRM197 to make it more effective at stimulating immune memory. It is a component of authorised meningococcal vaccines including Nimenrix (meningococcal groups A, C, W-135 and Y conjugate vaccine) and MenFive (meningococcal A, C, Y, W, X polysaccharide conjugate vaccine). The Buckinghamshire NHS formulary lists meningococcal polysaccharide A, C, W135 and Y vaccines under the trade names Menveo, Nimenrix and MenQuadfi.
How does N. meningitidis group Y polysaccharide work?
The polysaccharide itself is recognised by the innate immune system. Research shows that meningococcal capsular polysaccharides can trigger inflammatory responses through two immune receptors, TLR2 and TLR4-MD-2, leading to the release of signalling molecules called cytokines such as TNF-α, IL-6 and IL-8.
When the polysaccharide is conjugated to a carrier protein in a vaccine, the immune system generates antibodies specifically against the group Y capsule. These antibodies can recognise and help eliminate Neisseria meningitidis serogroup Y bacteria, providing protection against invasive meningococcal disease.
Which conditions is it used or studied for?
Vaccines containing N. meningitidis group Y polysaccharide are used to protect against disease caused by Neisseria meningitidis, particularly serogroup Y. The conditions targeted include:
- Meningococcal disease — a serious bacterial infection that can cause meningitis (inflammation of the membranes around the brain and spinal cord) and septicaemia (blood poisoning).
- Invasive meningococcal group Y infection — disease specifically caused by serogroup Y bacteria, which is one of the serogroups covered by the quadrivalent and pentavalent vaccines.
In the UK, meningococcal polysaccharide A, C, W135 and Y vaccines are used in the routine national immunisation schedule and in secondary care around splenectomy (removal of the spleen) and for occupational health. They should not be prescribed on the NHS exclusively for travel purposes.
How is N. meningitidis group Y polysaccharide given?
N. meningitidis group Y polysaccharide is given as part of a vaccine by intramuscular injection. The standard dose is 0.5 ml. In the MenFive product, each 0.5 ml dose contains 5 µg of N. meningitidis group Y polysaccharide conjugated to a carrier protein.
MenFive is supplied as a freeze-dried powder that is reconstituted with 2.5 ml of sodium chloride injection before use, and is stored at 2–8°C. Nimenrix is supplied as a powder and solvent for solution for injection in a pre-filled syringe.
What do the clinical trials show?
The clinical trial registry data provided includes one Phase 2 trial (NCT06989359) with 45 participants, registered as authorised. The trial is titled \"Phase 2 Study of ADX-038 in Complement-Mediated Kidney Disease\" and its primary outcome is the incidence and severity of treatment-emergent adverse events (TEAEs), measuring safety and tolerability.
In this trial, vaccines containing N. meningitidis group Y polysaccharide — specifically Nimenrix — appear as interventions alongside other vaccines (Prevenar 20, Infanrix hexa, Bexsero) and the investigational product ADX-038. The trial evaluates vaccine responses in the context of complement-mediated kidney disease.
The Nimenrix paediatric assessment report describes a clinical study (C0921062) submitted to the European Medicines Agency, which evaluated the vaccine in a paediatric development programme.
What side effects are known?
The supplementary sources provided do not contain a detailed side effect profile for N. meningitidis group Y polysaccharide. The research article on capsular polysaccharides describes inflammatory responses triggered by the polysaccharide through TLR2 and TLR4-MD-2 pathways, with dose-dependent release of cytokines including TNF-α, IL-6, IL-8 and CXCL10, as well as nitric oxide from macrophages. These are laboratory findings about the innate immune recognition of the polysaccharide, not clinical side effect data from the vaccines.