Ty21a
Oral live attenuated typhoid vaccine, WHO-recommended since 1983.
Ty21a is an oral live-attenuated typhoid vaccine made from a weakened Ty2 strain of Salmonella Typhi. It has several genes, including those for producing the Vi antigen, removed to make it safe while still triggering an immune response. The World Health Organization lists it as one of three recommended typhoid vaccines.
Quick Facts
- Target
- Typhoid
- Vaccine type
- attenuated
- Trade name
- Vivotif
- Legal UK
- POM
- Legal US
- Rx-only
- Routes of administration
- Oral
- CAS number
- 1704529-13-4
Facts from the source article.
Did You Know?
- The Vi polysaccharide vaccine is also effective at preventing typhoid fever.
- Ty21a may provide cross-protection against paratyphoid fever A and B.
- A newer Vi-rEPA vaccine is being tested and may offer longer-lasting protection.
Dosing
The recommended dose varies by country and preparation; at least three doses are required for protection. In the US and Canada, an initial course of four doses on alternate days is recommended, with a booster after five years in the US and after seven years in Canada. In Australia and Europe, an initial course of three doses on alternate days is recommended, with a booster every three years for those in endemic areas but every year for travelers from non-endemic to endemic areas.
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