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Vaccine description
Target disease Typhoid
Type ?
Clinical data
Legal status ?
Routes oral
CAS number  YesY
ATC code J07AP01
 YesY (what is this?)  (verify)

Ty21a is a live attenuated bacterial vaccine that protects against typhoid. It is one of two typhoid vaccines currently recommended by the World Health Organization.[1] The vaccine offers a statistically significant protection for the first three years, with between 8% to 54% effectiveness for the first year and between 40% to 71% for the second year.[2] The vaccine is most commonly used to protect travellers to endemic countries, but there is no reason why the vaccine could not be used in large scale public prevention programmes.[1]

The vaccine is given by mouth. The vaccine is presented either as capsules or a liquid suspension. The vaccine must be stored at 2 to 8 °C, but will retain its potency for 14 days at 25°C.[1]


The recommended dose varies according to country.

In the US and Canada, an initial course of 4 doses on alternate days is recommended. Full protection is achieved 7 days after the last dose. In the US, a booster dose is recommended after 5 years. In Canada, a booster dose is recommended after 7 years.

In Australia and Europe, an initial course of 3 doses on alternate days is recommended. Protection is achieved 7 days after the last dose. A booster is recommended every 3 years for people living in endemic areas, but every year for people travelling from non-endemic to endemic areas.[3]


  1. ^ a b c World Health Organization (2008). "Typhoid vaccines: WHO position paper". Weekly Epidemiological Record 83 (6): 49–60. PMID 18260212. 
  2. ^ Fraser A, Goldberg E, Acosta CJ, Paul M, Leibovici L (2007). "Vaccines for preventing typhoid fever". In Fraser, Abigail. Cochrane Database Syst Rev (3): CD001261. doi:10.1002/14651858.CD001261.pub2. PMID 17636661. 
  3. ^ Salisbury, D; Ramsay, M; Noakes, K. ""Chapter 33: Typhoid"". Immunisation against infectious disease. Department of Health. p. 418. ISBN 0-11-322528-8.