Vi capsular polysaccharide vaccine
（重定向自Typhim Vi）
Not to be confused with Ty21a. For an overview of vaccines against typhoid fever, see Typhoid vaccine.
The Vi capsular polysaccharide vaccine (or ViCPS) is one of two vaccines recommended by the World Health Organisation for the prevention of typhoid (the other is Ty21a). It 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 (Vi bound to a non-toxic recombinant Pseudomonas aeruginosa exotoxin, or Vi-rEPA) has enhanced efficacy, including protection of children under 5 years of age.