Vi capsular polysaccharide vaccine

Vi capsular polysaccharide vaccine
Typhoid
Vaccine type	Polysaccharide
Clinical data
Trade names	Typherix, Typhim VI
AHFS/Drugs.com	Multum Consumer Information
Routes of; administration	intramuscular injection, subcutaneous injection[clarification needed]
ATC code	J07AP03 (WHO) ;
Legal status
Legal status	US: ℞-only;
Identifiers
CAS Number	1704529-13-4 ;
ChemSpider	none;
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The Vi capsular polysaccharide vaccine (or ViCPS) is a

typhoid (another is Ty21a). 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

.

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.^[citation needed]

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 CDC recommend 14 days). The vaccine is not effective in children under the age of two.To maintain immunity, the vaccine should be repeated every three years.^{[citation needed]}

Efficacy and duration of protection

The vaccine offers effective protection the first year after being given (with between 50% and 80% efficacy), second year (31% to 76%), and third year cumulative efficacy of around 55%.^[1]

Biology

The Vi polysaccharide, or Vi antigen, is part of the bacterial capsule found outside of the typhoid bacterium, Salmonella enterica subsp. enterica ser. Typhi. It is produced by the action of a single gene cluster in the cytoplasm and transported to the surface. This antigen contributes to much of typhoid's virulence, and is important for the infection of intestinal epithelial cells. It is also produced by S. enterica ser. Paratyphi C, the causative agent of paratyphoid fever C.^[2]