Salmonella Typhi Ty21a Live Antigen (Ty21a) Patient Guide
Salmonella Typhi Ty21a Live Antigen (Ty21a) is a live oral vaccine used to help prevent typhoid fever caused by Salmonella Typhi. It is usually taken before travel to areas where typhoid is a risk and is not used to treat an existing infection. It does not replace safe food and water precautions.
Ty21a is usually taken as four capsules on alternate days, with the final dose completed at least one week before travel. Ask a doctor or pharmacist before taking it if you are pregnant, immunocompromised, taking antibiotics, or unsure whether it is suitable for you.
Key facts at a glance
- RxNorm
- 762595
- Generic
- Salmonella Typhi Ty21a Live Antigen
- Class
- unclassified
- Brands
- Vivotif
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- capsule
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 31, 2026. · Read our editorial policy