Medical use
In the late twentieth century, oral cholera vaccines started to be used on a massive scale, with millions of vaccinations taking place, as a tool to control cholera outbreaks in addition to the traditional interventions of improving safe water supplies, sanitation, handwashing and other means of improving hygiene. The Dukoral monovalent vaccine from Sweden, which combines formalin, heat-killed whole cells of Vibrio cholerae O1 and a recombinant cholera toxin B subunit, was licensed in 1991, mainly for travellers. Out of a million doses sold during the following decade, 63 negative side effects were reported. The Shanchol/mORCVAX bivalent vaccine, which combines the O1 and O139 serogroups, was originally licensed in Vietnam in 1997 and given in 20 million doses to children in Vietnam during the following decade. As of 2010, Vietnam continued to incorporate oral cholera vaccination in its public health programme, administering the vaccination through targeted mass vaccination of school-aged children in cholera endemic regions.The cholera vaccine is widely used by backpackers and persons visiting locations where there is a high risk of cholera infection. However, since it does not provide 100 percent immunity from the disease, food hygiene precautions are also recommended 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 two years of age and older, Shanchol for children one year of age and older.
Cholera vaccines are vaccines that are effective at preventing cholera. For the first six months after vaccination they provide about 85 percent protection, which decreases to 50 percent or 62 percent during the first year. After two years the level of protection decreases to less than 50 percent. When enough of the population is immunized, it may protect those who have not been immunized (known as herd immunity).The World Health Organization (WHO) recommends the use of cholera vaccines in combination with other measures among those at high risk. With the oral vaccine, two or three doses are typically recommended. The duration of protection is two years in adults and six months in children aged 2–5 years. A single dose vaccine is available for those traveling to an area where cholera is common. In 2010, in some countries an injectable cholera vaccine was available.The available types of oral vaccine are generally safe. Mild abdominal pain or diarrhea may occur. They are safe in pregnancy and in those with poor immune function. They are licensed for use in more than 60 countries. In countries where the disease is common, the vaccine appears to be cost effective.The first vaccines used against cholera were developed in the late 1800s. They were the first widely used vaccine that was made in a laboratory. Oral vaccines were first introduced in the 1990s. It is on the World Health Organizations List of Essential Medicines.