Salmonella typhi strain ty 21a: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
Salmonella typhi strain ty 21a: clinical details
Prescribing considerations
- Confirm vaccination is indicated after destination, activity, accommodation and occupational-risk assessment.
- Licensed for adults and children aged 5 years and older who can swallow an intact gastro-resistant capsule.
- Review recent or planned antibiotics, antibacterial sulfonamides and malaria prophylaxis.
- Emphasise that vaccination does not replace food and water precautions.
- Check suitability of lactose, sucrose, gelatin and casein-derived excipients.
Contraindications and cautions
- Hypersensitivity to the active substance, an excipient or a previous ingestion of the product
- Congenital or acquired immune deficiency, including immunosuppressive or antimitotic treatment
- Current acute febrile or gastrointestinal illness; postpone until recovery
- Rare hereditary disorders incompatible with the lactose or sucrose content
Monitoring
- No routine laboratory monitoring or established serological correlate of protection is specified.
- Ensure arrangements are available to recognise and manage anaphylaxis.
- Review significant adverse reactions and report suspected reactions through the MHRA Yellow Card scheme.
Clinical pharmacology
Ty21a lacks the Vi capsular virulence factor and has a galE mutation that restricts replication through defective cell-wall biosynthesis. It acts locally in the gut and induces mucosal IgA, antibody-secreting cells and gut-homing cellular immune responses.
Formulation and product differences
- The UK product is a hard gastro-resistant oral capsule requiring refrigeration and protection from light.
- The capsule contains viable and inactive Ty21a organisms, lactose, sucrose, gelatin and casein acid hydrolysate.
- It differs from injectable non-live typhoid vaccines and is unsuitable for people unable to swallow the capsule intact.
Salmonella typhi strain ty 21a interactions
Because this vaccine contains living bacteria, some medicines may reduce the immune response.
Antibiotics and antibacterial sulfonamides
They may inhibit the vaccine organisms and reduce effectiveness. Coordinate vaccination with the prescriber or pharmacist.
Malaria prophylaxis
Some antimalarial medicines may interfere with the vaccine. Coordinate both plans before travel.
Other live attenuated vaccines
It may be given with yellow fever, oral cholera CVD 103-HgR and oral polio vaccines, but interaction data for other live vaccines are limited.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.