Salmonella typhi strain ty 21a at a glance
Class
Live attenuated oral bacterial vaccine
Licensed role
Active immunisation against typhoid fever in adults and children aged 5 years and older
Administration
Swallow the gastro-resistant capsule whole on an empty stomach with cold or lukewarm water
Storage
Keep refrigerated and protect the blister from light
What is Salmonella typhi strain ty 21a used for?
Its licensed use is oral immunisation against typhoid fever caused by Salmonella Typhi. Vaccination may be considered after assessing travel or occupational risk.
Reducing typhoid risk in eligible travellers
Occupational protection for eligible laboratory personnel who may handle Salmonella Typhi
How does Salmonella typhi strain ty 21a work?
The weakened Ty21a bacteria remain mainly in the intestine and stimulate local and systemic immune responses without causing typhoid fever in suitable recipients.
How to take Salmonella typhi strain ty 21a
Follow the instructions from the prescriber or vaccination service. Inspect the blister and capsule, then swallow the capsule promptly and whole without crushing or chewing it.
Take on an empty stomach and before the next meal.
Use cold or lukewarm water, not a hot drink.
Keep the capsules refrigerated until required.
Continue careful food, water and hand hygiene because vaccination is not fully protective.
Salmonella typhi strain ty 21a side effects
Common or expected effects
- Headache
- Abdominal pain
- Nausea or vomiting
- Diarrhoea
- Fever
- Skin rash
Get urgent medical advice
- Severe allergic reaction, including facial or throat swelling, breathing difficulty, fainting or shock
Salmonella typhi strain ty 21a in pregnancy
This live vaccine is generally avoided during pregnancy when a suitable non-live injectable typhoid vaccine is available. It should be used only when clearly needed because direct pregnancy data are limited. Discuss the travel risk and alternatives with a healthcare professional.
Salmonella typhi strain ty 21a while breastfeeding
Direct product-specific evidence is limited, and the product information recommends use only when clearly needed. UK specialist guidance considers vaccines, including live vaccines other than yellow fever vaccine, generally compatible with breastfeeding. Individual assessment is appropriate, especially if the infant may be immunosuppressed, premature or unwell.
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.
Common questions about Salmonella typhi strain ty 21a
Answers are fully visible for fast scanning and source review.
Does it prevent every case of typhoid?
No. It reduces risk but does not provide complete protection, so careful food, water and hand hygiene remain essential.
Does it protect against paratyphoid or other Salmonella infections?
It is licensed against typhoid caused by Salmonella Typhi. Reliable protection against paratyphoid has not been established, and it does not protect against Salmonella types that commonly cause diarrhoeal illness.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.