Vi capsular polysaccharide vaccine


The Vi capsular polysaccharide vaccine is a typhoid vaccine recommended by the World Health Organization for the prevention of typhoid. The vaccine was first licensed in the US in 1994 and is made from the purified Vi capsular polysaccharide from the Ty2 Salmonella Typhi strain; it is a subunit vaccine. A newer conjugate form of the vaccine has enhanced efficacy, including protection of children under 5 years of age.

Medical uses

The vaccine may be used in endemic areas in order to prevent typhoid. It is also commonly used to protect people who are traveling to parts of the world where typhoid is endemic.

Dosing

The vaccine is injected either under the skin or into a muscle at least seven days before traveling to the typhoid-affected area. The vaccine is not effective in children under the age of two.
To maintain immunity, the vaccine should be repeated every three years.

Efficacy and duration of protection

The vaccine offers effective protection the first year after being given and the second year, but not after that.

Trade names