Cholera vaccine
Cholera vaccines are designed to provide protection against cholera, a severe gastrointestinal disease caused by the Vibrio cholerae bacterium, primarily transmitted through contaminated food and water. Available internationally since 1991, these vaccines can offer protection for up to three years for more than 50% of those vaccinated. There are three primary vaccines: Dukoral, Shanchol, and Euvichol-Plus, which are administered orally and typically require two doses for optimal efficacy. The Dukoral vaccine offers short-term protection, particularly for travelers, while Shanchol and Euvichol-Plus provide longer-lasting immunity, especially beneficial for young children.
Despite their availability, several challenges hinder widespread vaccination, including high costs, limited supply, and logistical issues related to administering the two-dose regimen. The World Health Organization (WHO) has noted significant cholera outbreaks globally, exacerbated by factors such as climate change, natural disasters, and armed conflicts. In response to these challenges, WHO has started recommending a one-dose vaccination approach to rapidly address outbreaks. Vaccination is a critical component of cholera control, alongside improving water safety and sanitation, and educating communities on prevention methods.
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Cholera vaccine
Definition
Cholera vaccines can offer up to three years protection for more than 50 percent of the treated population against the sometimes fatal disease cholera. The disease is caused by eating food or water contaminated by the Vibrio cholerae bacterium.
Cholera has multiplied during the first decades of the twenty-first century because increased numbers of people are moving from areas at high risk for cholera to other regions, at a pace too fast for local governments and health authorities to provide safe water and sanitation.
Cholera vaccines have been available internationally since 1991. Over 100 million doses of cholera vaccines have been administered through mass vaccination campaigns in areas experiencing outbreaks and other hotspots. However, many countries have not been able to use vaccines because of high cost, limited supply, and logistical problems in providing two doses.
The World Health Organization (WHO) reports there are 1.3 million to 4 million cases of cholera each year, with an estimated 21,000 to 143,000 of these cases resulting in death.
Data collected by the WHO may represent only 5 to 10 percent of actual cases of cholera, because of the difficulty of keeping accurate records in the chaotic conditions in which cholera thrives, such as in natural disasters and civil unrest.
Vaccine Administration
The Dukoral vaccine is one of three vaccines prequalified by the WHO and can be given to anyone who is at least two years old. It provides short-term protection against V. cholerae for up to 90 percent of all age groups. Dukoral is used mostly for people traveling to other countries. The Shanchol and Euvichol-Plus vaccines, which use the same formula but are manufactured by two different companies, provide longer-term protection. Its formula is particularly effective in children younger than five years of age.
The Dukoral, Shanchol, and Euvichol-Plus vaccines are all administered orally, offering ease of administration and freedom from the risks of needle-borne infection. The vaccines are usually administered in two doses, between seven days and six weeks apart. Persons in areas of the world in which cholera is prevalent should receive booster shots every six months. Musocal vaccines are also under development for treatment of cholera.
In an unprecedented move, the WHO began recommending one-dose vaccines, instead of the usual two doses, in 2022, to quell a record number of cholera outbreaks that took place that year. The outbreaks were recorded in various locations around the world, including Africa, the Middle East, the Caribbean, and South Asia, and were the result of natural disasters, including floods and droughts, as well as armed conflicts. WHO officials made the decision over concerns of a shortage in vaccine supply. That shortage was made worse by an announcement from Shantha Biotechnics, which in 2022 produced about 15 percent of the world's supply of cholera vaccines, that it would suspend production of its vaccine by the end of that year. Experts found the situation extremely concerning and warned that such outbreaks were only likely to continue given the impact of climate change.
Impact
Vaccines are one facet of cholera eradication. They provide temporary protection while safe water and improved sanitation are secured. Community education on safe practices is also necessary. Persons who survive infection by V. cholerae develop a protective immunity.
Bibliography
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"Cholera." World Health Organization, 30 Mar. 2022, www.who.int/news-room/fact-sheets/detail/cholera. Accessed 8 Nov. 2022.
“Cholera Outbreak—Haiti, October, 2010.” Morbidity and Mortality Weekly Report 59 (November 5, 2010): 1411.
Nolen, Stephanie. "Cholera Outbreaks Surge Worldwide as Vaccine Supply Drains." The New York Times, 1 Nov. 2022, www.nytimes.com/2022/10/31/health/cholera-outbreaks-vaccine.html. Accessed 8 Nov. 2022.
Plotkin, Stanley A., Walter A. Orenstein, and Paul Offit. Vaccines. 5th ed. Philadelphia: Saunders/Elsevier, 2008.
Sridhar, Saranya. “An Affordable Cholera Vaccine: An Important Step Forward.” The Lancet 374 (2009): 1658-1660.
World Health Organization. “Cholera.” Fact Sheet No. 107. Available at http://www.who.int/mediacentre/factsheets/fs107.