In short
Neisseria meningitidis group A polysaccharide is a bacterial sugar used in vaccines against meningococcal disease, a severe infection of the brain lining and bloodstream. In the EU registry it appears as part of a paediatric investigation plan for a combined MenABCWY vaccine being developed to protect against five meningococcal groups (A, B, C, W and Y).
Key points
- Neisseria meningitidis group A polysaccharide is a component of conjugate vaccines against meningococcal serogroup A disease.
- It is part of a paediatric investigation plan (PIP) for a MenABCWY vaccine covering serogroups A, B, C, W and Y.
- The registered trial NCT06989359 is a Phase 2 study with 45 participants authorised in complement-mediated kidney disease.
- Trial vaccines containing meningococcal components are given as 0.5 ml intramuscular injections.
- The primary outcome in the registered trial is incidence and severity of treatment-emergent adverse events.
- The MenABCWY vaccine under development is intended for prevention of meningococcal disease caused by serogroups A, B, C, W and Y.
What is Neisseria meningitidis group A polysaccharide?
Neisseria meningitidis group A polysaccharide is a long-chain sugar molecule found on the surface of group A meningococcal bacteria. It is not used on its own as a medicine; instead, it is linked (conjugated) to a carrier protein to make a conjugate vaccine. The European Medicines Agency (EMA) lists it as an active substance within a paediatric investigation plan for a combined MenABCWY vaccine, where the group A polysaccharide is conjugated to tetanus toxoid carrier protein. The same polysaccharide appears in licensed quadrivalent meningococcal vaccines such as Menveo, Nimenrix and MenQuadfi, which cover groups A, C, W-135 and Y. In the UK dm+d browser it is listed under the name "Neisseria meningitidis group A capsular polysaccharide protein conjugate" as an ingredient of a solution for injection.
How does it work?
As a polysaccharide alone, the group A sugar provokes only a weak and short-lived immune response, particularly in young children. When chemically linked to a carrier protein such as tetanus toxoid, it becomes a conjugate vaccine: the immune system recognises the sugar as a foreign structure and produces antibodies against it. These antibodies bind to the surface of group A meningococcal bacteria, marking them for destruction and preventing them from causing invasive disease. The MenABCWY vaccine under development combines this conjugated group A polysaccharide with conjugates for groups C, W and Y and with recombinant proteins from group B bacteria, aiming to protect against all five major disease-causing serogroups in a single injection.
Which conditions is it used or studied for?
- Prevention of meningococcal disease (serogroups A, B, C, W and Y) — the MenABCWY vaccine containing this polysaccharide is being developed to prevent invasive meningococcal disease caused by all five serogroups.
- Complement-mediated kidney disease — the registered Phase 2 trial NCT06989359 lists meningococcal vaccines among its interventions while evaluating the safety and tolerability of another drug, ADX-038, in this condition.
How is it given?
The vaccines containing this polysaccharide are given as a suspension for injection by the intramuscular route. The EMA paediatric investigation plan records the pharmaceutical form as suspension for injection and the route of administration as intramuscular use. The NHS dm+d browser also describes the quadrivalent meningococcal conjugate vaccine as a solution for injection given intramuscularly, in 0.5 ml vials.
What do the clinical trials show?
The EU Clinical Trials Information System contains one authorised interventional trial, NCT06989359, that lists meningococcal vaccines among its interventions. The trial is in Phase 2 and plans to enrol 45 participants. Its stated primary objective is not to measure vaccine efficacy but to evaluate the safety and tolerability of ADX-038 in complement-mediated kidney disease; the vaccines, including Nimenrix (which contains group A polysaccharide) and Bexsero, are administered as part of the study interventions. The primary outcome measured is the incidence and severity of treatment-emergent adverse events (TEAEs). The trial is currently authorised, meaning recruitment has not yet been reported as completed in the registry.
What side effects are known?
The provided sources do not contain a side-effect profile specific to Neisseria meningitidis group A polysaccharide. The registered trial NCT06989359 measures the incidence and severity of treatment-emergent adverse events as its primary outcome, which means safety information is being collected during the study. The supplementary sources describe the vaccines only in terms of their composition, pharmaceutical form and place in immunisation schedules, without listing adverse reactions.