The Vi capsular polysaccharide vaccine (or ViCPS) is a

typhoid vaccine Typhoid vaccines are vaccines that prevent typhoid fever. Several types are widely available: typhoid conjugate vaccine (TCV), Ty21a (a live oral vaccine) and Vi capsular polysaccharide vaccine (ViPS) (an injectable subunit vaccine). Dep ...

recommended by the

World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...

for the prevention of

typhoid Typhoid fever, also known simply as typhoid, is a disease caused by ''Salmonella enterica'' serotype Typhi bacteria, also called ''Salmonella'' Typhi. Symptoms vary from mild to severe, and usually begin six to 30 days after exposure. Often ther ...

(another is

Ty21a Ty21a is a live attenuated bacterial vaccine that protects against typhoid. First licensed in Europe in 1983 and in the United States in 1989, it is an orally administered, live-attenuated Ty2 strain of S. Typhi in which multiple genes, includin ...

). 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 subunit vaccine is a vaccine that contains purified parts of the pathogen that are antigenic, or necessary to elicit a protective immune response. Subunit vaccine can be made from dissembled viral particles in cell culture or recombinant DNA expr ...

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

CDC The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency under the Department of Health and Human Services (HHS), and is headquartered in Atlanta, ...

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.

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%.

Biology

The Vi polysaccharide, or Vi antigen, is part of the

bacterial capsule The bacterial capsule is a large structure common to many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell. It is a well-organized layer, not easily wash ...

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 Paratyphoid fever, also known simply as paratyphoid, is a bacterial infection caused by one of three types of '' Salmonella enterica''. Symptoms usually begin 6–30 days after exposure and are the same as those of typhoid fever. Often, a gradu ...

Trade names

Typhim VI The Vi capsular polysaccharide vaccine (or ViCPS) is a typhoid vaccine recommended by the World Health Organization for the prevention of typhoid (another is Ty21a). The vaccine was first licensed in the US in 1994 and is made from the purified Vi ...

(manufactured by

Sanofi Pasteur Sanofi Pasteur is the vaccines division of the French multinational pharmaceutical company Sanofi. Sanofi Pasteur is the largest company in the world devoted entirely to vaccines. It is one of four global producers of the yellow fever vaccin ...

) *

Typherix The Vi capsular polysaccharide vaccine (or ViCPS) is a typhoid vaccine recommended by the World Health Organization for the prevention of typhoid (another is Ty21a). The vaccine was first licensed in the US in 1994 and is made from the purified Vi ...

(manufactured by

GlaxoSmithKline GSK plc (an acronym from its former name GlaxoSmithKline plc) is a British Multinational corporation, multinational Pharmaceutics, pharmaceutical and biotechnology company with headquarters in London. It was established in 2000 by a Mergers an ...

)

Research

A newer conjugate form of the vaccine (Vi bound to a non-toxic recombinant ''

Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common Bacterial capsule, encapsulated, Gram-negative bacteria, Gram-negative, Aerobic organism, aerobic–facultative anaerobe, facultatively anaerobic, Bacillus (shape), rod-shaped bacteria, bacterium that can c ...

exotoxin A The Pseudomonas exotoxin (or exotoxin A) is an exotoxin produced by ''Pseudomonas aeruginosa''. ''Vibrio cholerae'' produces a similar protein called the Cholix toxin (). It inhibits elongation factor-2. It does so by ADP-ribosylation of EF2 u ...

, or Vi-rEPA) has enhanced efficacy, including protection of children under 5 years of age. The

typhoid conjugate vaccine The Vi capsular polysaccharide vaccine (or ViCPS) is a typhoid vaccine recommended by the World Health Organization for the prevention of typhoid (another is Ty21a). The vaccine was first licensed in the US in 1994 and is made from the purified Vi ...

("Typbar-TCV") is another Vi-based conjugate vaccine, in this case linked to

Tetanus toxoid Tetanus vaccine, also known as tetanus toxoid (TT), is a toxoid vaccine used to prevent tetanus. During childhood, five doses are recommended, with a sixth given during adolescence. After three doses, almost everyone is initially immune, but ...

. It has been approved.

References

Subunit vaccines Typhoid fever {{Vaccine-stub