Vaccine description | |
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Target | Typhoid |
Clinical data | |
Trade names | Typhim Vi, Vivotif |
AHFS/ Drugs.com | Monograph |
MedlinePlus | a607028 |
Pregnancy category |
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ATC code | |
Legal status | |
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ChemSpider |
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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 has been shown to be efficacious in children. [4]
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]
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]
Depending on the formulation it can be given starting at the age of two (ViPS), six (Ty21a), or six months (TCV). [1]