Cholera is an acute diarrhoeal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. During 2017, 1,227,391 cases were notified from 34 countries, including 5,654 deaths. However cases of cholera are under-reported and it is estimated that every year, there are roughly 1.3 to 4 million cases, and 21,000 – 143,000 deaths worldwide due to cholera. Cholera cases have increased steadily since 2005, occurring in many places including Africa, Southeast Asia, and Haiti. Cholera is now endemic in many countries.
Cholera transmission is closely linked to inadequate access to clean water and sanitation facilities. Typical at-risk areas include peri-urban slums, and camps for internally displaced persons or refugees, where minimum the requirements of clean water and sanitation are not been met. The consequences of a humanitarian crisis, and the displacement of populations to inadequate and overcrowded camps, can increase the risk of cholera transmission, should the bacteria be present or introduced.
Most people infected with V. cholerae are asymptomatic or have mild or moderate symptoms. However approximately one in ten (5-10%) of infected persons will have severe cholera. This can lead to acute renal failure, severe electrolyte imbalances and coma. If untreated, severe dehydration can rapidly lead to shock and death within hours.
Oral cholera vaccines, in areas known to be high risk for cholera, supplement core prevention efforts to improve water and sanitation. Currently there are three WHO pre-qualified oral cholera vaccines (OCV). All three vaccines require two doses for full protection. One is administered with a buffer solution that, for adults, requires 150 ml of clean water. The other vaccines do not require a buffer solution for administration. Two doses will provide moderate protection against cholera for two to five years in adults.
Vaccination campaigns have often been carried out in response to outbreaks and humanitarian crises, such as in Yemen and among the Rohingya refugee population in Bangladesh. As the global stockpile continues to increase, preventive cholera vaccination use has become more common. Gavi has supported the global oral cholera vaccine stockpile since 2014