Cholera vaccine

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Cholera vaccine
Vaccine description
Target disease Cholera
Type Killed/Inactivated
Clinical data
AHFS/Drugs.com Micromedex Detailed Consumer Information
Pregnancy cat. C (US)
Legal status ?
Identifiers
CAS number  YesY
ATC code J07AE01 J07AE02
 N (what is this?)  (verify)

Cholera vaccine is a vaccine used against cholera.[1] The first vaccines used against cholera were developed in the late nineteenth century. These injected whole cell vaccine became increasingly popular until they were replaced by oral vaccines starting in the 1980s. Both oral and injectable forms are about 50-60% effective in the first year.[2][3]

It is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system.[4]

Medical use[edit]

Oral cholera vaccines are increasingly used as an additional tool to control cholera outbreaks in combination with the traditional interventions to improve water supply, sanitation, handwashing and other means to improve hygiene. Since licensure of Dukoral and Shanchol, over a million doses of these vaccines have been deployed in various mass oral cholera campaigns around the world.[5] In addition, Vietnam incorporates oral cholera vaccination in its public health programme and over 9 million doses have been administered through targeted mass vaccination or immunization of school-aged children in cholera endemic regions.

The cholera vaccine is largely used by backpackers and persons visiting locations where there is a high risk of cholera infection. However, since it does not provide 100% immunity from the disease, food hygiene precautions should also be taken into consideration when visiting an area where there is a high risk of becoming infected with cholera. Although the protection observed has been described as "moderate", herd immunity can multiply the effectiveness of vaccination. Dukoral has been licensed for children 2 years of age and older, Shanchol for children 1 year of age and older. The administration of the vaccine to adults confers additional indirect protection (herd immunity) to children.

The WHO recommends both preventive and reactive use of the vaccine, making the following key statements:[6] WHO recommends that current available cholera vaccines be used as complements to traditional control and preventive measures in areas where the disease is endemic and should be considered in areas at risk for outbreaks. Vaccination should not disrupt the provision of other high priority health interventions to control or prevent cholera outbreaks. Reactive vaccination might be considered in view of limiting the extent of large prolonged outbreaks, provided the local infrastructure allows it, and an in-depth analysis of past cholera data and identification of a defined target area have been performed.

The WHO has now established a revolving stockpile of 2 million OCV doses.[7] The plan is increase the size of this stockpile over the coming years with financial support of the GAVI Alliance.[8]

Effectiveness[edit]

Oral[edit]

Comparison of the currently manufactured oral cholera vaccines

Oral vaccines provide protection in 52% of cases the first year following vaccination and in 62% of cases the second year.[3] There are two variants of the oral vaccine currently in use: WC-rBS and BivWC. WC-rBS (marketed as "Dukoral") is a monovalent inactivated vaccine containing killed whole cells of V. cholerae O1 plus additional recombinant cholera toxin B subunit. BivWC (marketed as "Shanchol" and "mORCVAX") is a bivalent inactivated vaccine containing killed whole cells of V. cholerae O1 and V. cholerae O139. mORCVAX is only available in Vietnam.

Bacterial strains of both Inaba and Ogawa serotypes and of El Tor and Classical biotypes are included in the vaccine. Dukoral is taken orally with bicarbonate buffer, which protects the antigens from the gastric acid. The vaccine acts by inducing antibodies against both the bacterial components and CTB. The antibacterial intestinal antibodies prevent the bacteria from attaching to the intestinal wall thereby impeding colonisation of V. cholerae O1. The anti-toxin intestinal antibodies prevent the cholera toxin from binding to the intestinal mucosal surface thereby preventing the toxin-mediated diarrhoeal symptoms.[9]

Injectable[edit]

Although no longer in use, the injected cholera vaccines are effective for people living where cholera is endemic. They offer significant degrees of protection for up to two years after a single shot, and for three to four years with annual booster. They reduce the risk of death from cholera by 50% in the first year after vaccination.[2]

References[edit]

  1. ^ Cholera vaccines at the US National Library of Medicine Medical Subject Headings (MeSH)
  2. ^ a b Graves PM, Deeks JJ, Demicheli V, Jefferson T (2010). "Vaccines for preventing cholera: killed whole cell or other subunit vaccines (injected)". Cochrane Database Syst Rev (8): CD000974. doi:10.1002/14651858.CD000974.pub2. PMID 20687062. 
  3. ^ a b Sinclair D, Abba K, Zaman K, Qadri F, Graves PM (2011). "Oral vaccines for preventing cholera". Cochrane Database Syst Rev (3): CD008603. doi:10.1002/14651858.CD008603.pub2. PMID 21412922. 
  4. ^ "WHO Model List of EssentialMedicines". World Health Organization. October 2013. Retrieved 22 April 2014. 
  5. ^ Harris, JB; LaRocque, RC; Qadri, F; Ryan, ET; Calderwood, SB (Jun 30, 2012). "Cholera.". Lancet 379 (9835): 2466–76. doi:10.1016/s0140-6736(12)60436-x. PMID 22748592. 
  6. ^ Oral cholera vaccines in mass immunization campaigns: guidance for planning and use. World Health Organization. 2010. ISBN 9789241500432. 
  7. ^ "Oral cholera vaccine stockpile". World Health Organization. Retrieved 18 December 2013. 
  8. ^ "GAVI Board Approves Support to Expand Oral Cholera Vaccine Stockpile". The Task Force on Global Health. Retrieved 18 December 2013. 
  9. ^ "Dukoral Canadian Product Monograph Part III: Consumer Information". Retrieved 8 May 2013.