In short
Diphtheria toxoid adsorbed on aluminium phosphate is a vaccine component used in combination vaccines that protect against diphtheria and other infectious diseases. It appears as part of the Vaxelis vaccine in one completed Phase 3 clinical trial (NCT05856396) that studied maternal determinants of infant immunity to pertussis, also known as whooping cough, in 240 participants.
Key points
- Diphtheria toxoid adsorbed on aluminium phosphate is a vaccine component used in combination vaccines against diphtheria and other infections.
- One Phase 3 trial (NCT05856396) studied the substance as part of the Vaxelis vaccine in 240 participants.
- The trial focused on whooping cough (pertussis) and how maternal vaccination during pregnancy affects infant immunity.
- The primary outcome measured was the magnitude of antibody responses to pertussis vaccination.
- The trial status is Completed.
- The substance is listed in NHS formularies as part of routine childhood and maternal immunisation schedules in the UK.
What is diphtheria toxoid adsorbed on aluminium phosphate?
Diphtheria toxoid adsorbed on aluminium phosphate is a vaccine component that protects against diphtheria, a serious bacterial infection caused by Corynebacterium diphtheriae. The toxoid is a chemically inactivated form of the diphtheria toxin that has been treated so it can no longer cause disease but can still trigger an immune response. The aluminium phosphate acts as an adjuvant, a substance that enhances the body's immune response to the vaccine. The substance is not given on its own but is included as one component of combination vaccines such as Vaxelis, Repevax, Revaxis and Infanrix hexa, which protect against several diseases at once.
How does diphtheria toxoid adsorbed on aluminium phosphate work?
Diphtheria toxoid works by teaching the immune system to recognise and fight the diphtheria toxin before a real infection occurs. When the toxoid is injected, immune cells identify it as foreign and produce antibodies against it. The aluminium phosphate adjuvant strengthens this response by keeping the toxoid at the injection site longer and stimulating a stronger immune reaction. If the vaccinated person later encounters the actual diphtheria bacterium, the immune system is already prepared to neutralise the toxin quickly and prevent illness.
Which conditions is it used or studied for?
- Diphtheria — a serious bacterial infection that can cause breathing difficulties, heart problems and nerve damage. The toxoid is included in routine childhood and booster vaccines to prevent this disease.
- Whooping cough (pertussis) — the clinical trial NCT05856396 studied the substance as part of the Vaxelis combination vaccine, focusing on how maternal vaccination during pregnancy affects antibody transfer to infants and their subsequent vaccine responses.
- Tetanus — the combination vaccines containing diphtheria toxoid also protect against tetanus, a bacterial infection that causes painful muscle spasms.
- Poliomyelitis — several combination vaccines containing the toxoid also include inactivated poliovirus components to protect against polio.
How is diphtheria toxoid adsorbed on aluminium phosphate given?
Diphtheria toxoid adsorbed on aluminium phosphate is given by intramuscular injection as part of combination vaccines. In the clinical trial NCT05856396, the Vaxelis vaccine containing this substance was administered as a 0.5 ml suspension for injection in a pre-filled syringe. NHS formulary records describe the combination vaccines as suspensions for injection, with some supplied in pre-filled syringes. The vaccines are used within routine national immunisation schedules in the UK, including primary and booster vaccination of infants and toddlers, and vaccination of pregnant women to protect newborns from pertussis.
What do the clinical trials show?
One completed Phase 3 clinical trial (NCT05856396) included diphtheria toxoid adsorbed on aluminium phosphate as a component of the Vaxelis combination vaccine. The trial enrolled 240 participants and studied maternal determinants of infant immunity to pertussis. The study investigated women immunised during pregnancy and measured how maternal antibodies are transferred to the newborn and how infants respond to their own pertussis vaccinations. The primary outcome was the magnitude of the antibody responses to pertussis vaccination. The trial also used Triaxis, a reduced-antigen diphtheria, tetanus and pertussis vaccine, as a comparison product. The trial status is Completed, meaning the study has finished and results may be available or in preparation.
What side effects are known?
The provided sources do not contain specific side effect information for diphtheria toxoid adsorbed on aluminium phosphate. NHS formulary entries refer to the UK Health Security Agency Green Book for detailed guidance on vaccine safety and administration, but do not list side effects directly.