Typhoid vaccine
Vaccines that prevent typhoid fever From Wikipedia, the free encyclopedia
Typhoid vaccines are vaccines that prevent typhoid fever.[1][2][3] Several types are widely available: typhoid conjugate vaccine (TCV), Ty21a (a live oral vaccine) and Vi capsular polysaccharide vaccine (ViPS) (an injectable subunit vaccine). They are about 30 to 70% effective in the first two years, depending on the specific vaccine in question. The Vi-rEPA vaccine is efficacious in children.[4]
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| Vaccine description | |
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| Target | Typhoid |
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| Trade names | Typhim Vi, Vivotif |
| AHFS/Drugs.com | Monograph |
| MedlinePlus | a607028 |
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The World Health Organization (WHO) recommends vaccinating all children in areas where the disease is common.[1] Otherwise they recommend vaccinating those at high risk.[1] Vaccination campaigns can also be used to control outbreaks of disease.[1] Depending on the vaccine, additional doses are recommended every three to seven years.[1] In the United States the vaccine is only recommended in those at high risk such as travelers to areas of the world where the disease is common.[5]
The vaccines available as of 2018 are very safe.[1] Minor side effects may occur at the site of injection.[1] The injectable vaccine is safe in people with HIV/AIDS and the oral vaccine can be used as long as symptoms are not present.[1] While it has not been studied during pregnancy, the non-live vaccines are believed to be safe while the live vaccine is not recommended.[1]
The first typhoid vaccines were developed in 1896 by Almroth Edward Wright, Richard Pfeiffer, and Wilhelm Kolle.[6] Due to side-effects newer formulations are recommended as of 2018.[1] It is on the World Health Organization's List of Essential Medicines.[7][8]
Medical uses
Ty21a, the Vi capsular polysaccharide vaccine, and Vi-rEPA are effective in reducing typhoid fever with low rates of adverse effects.[4] Newer vaccines such as Vi-TT (PedaTyph) are awaiting[when?] field trials to demonstrate efficacy against natural exposure.[4]
The oral Ty21a vaccine prevents around one-half of typhoid cases in the first three years after vaccination. The injectable Vi polysaccharide vaccine prevented about two-thirds of typhoid cases in the first year and had a cumulative efficacy of 55% by the third year. The efficacy of these vaccines has only been demonstrated in children older than two years.[4] Vi-rEPA vaccine, a new conjugate form of the injectable Vi vaccine, may be more effective and prevents the disease in many children under the age of five years.[9] In a trial in 2-to-5-year-old children in Vietnam, the vaccine had more than 90 percent efficacy in the first year and protection lasted at least four years.[10]
Schedule
Depending on the formulation it can be given starting at the age of two (ViPS), six (Ty21a), or six months (TCV).[1]
Types
- Vi capsular polysaccharide vaccine: Typhim VI (Sanofi Pasteur);[11] Typherix (GSK)
- Ty21a oral vaccine: Vivotif (Emergent BioSolutions)[12]
- Typhoid conjugate vaccine: Typbar-TCV (Bharat Biotech)[13]
- Combined hepatitis A and Vi polysaccharide vaccine: ViVaxim and ViATIM (Sanofi Pasteur); Hepatyrix (GSK)
- Activated whole cell vaccine remains available in some parts of the developing world as of 2008[update].[1]
References
External links
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