About Cholera Vaccine
Cholera infections is generally rare among most travellers. All travelers to cholera-affected areas should follow safe food and water precautions and proper sanitation and personal hygiene measures as primary prevention strategies against cholera infection.
The World Health Organization and its partners are evaluating the use of newer tools (vaccines) to complement these traditional measures for prevention of cholera. Evidence on the use of oral cholera vaccines is evolving rapidly.
Oral cholera vaccines of demonstrated safety and effectiveness have recently become available for use by individuals. Some countries have already used oral cholera vaccines to immunize populations considered to be at high risk for cholera outbreaks.
There are four variants oral vaccines currently in use. Available products include Dukoral (WC-rBS), Shanchol, mORCVAX (BivWC) and Vaxchora (lyophilized CVD 103-HgR). For all four vaccines, there is evidence of safety and efficacy (approximately 66 to 85%) after two doses.
mORCVAX is licensed and produced exclusively in Vietnam. Vaxchora was approved by the US Food and Drug Administration in 2016 for persons 18-64 years old who are traveling to an area of active cholera transmission. Vaxchora is not approved for use outside of the United States.
Vaxchora is reported to to reduce the chance of severe diarrhea in people by 90% at 10 days after vaccination and by 80% at 3 months after vaccination. The safety and effectiveness of Vaxchora in pregnant or breastfeeding women is not yet known, and it is also not known how long protection lasts beyond 3 – 6 months after getting the vaccine. The effectiveness of Vaxchora has not been established in persons living in cholera-affected areas.
In a study of the efficacy of the Sanchol cholera vaccine (produced in India) used during an outbreak in Guinea in 2012, there is evidence that it might help stop an outbreak of the disease. The study was published in the New England Journal of Medicine, and there is evidence that 2-doses of the Sanchol vaccine was 86 percent effective in preventing immediate infection. This is the 1st time a vaccine has been tested as a way to stop transmission in the short-term. The Shanchol vaccine is the cheapest of the 3 oral cholera vaccines at USD 1.85 a dose.
In addition, the Shanchol vaccine contains killed cholera bacteria of different strains. Recently, a large study in India of its efficacy showed that it protected 65 percent of the recipients five years after vaccination. The other WHO prequalified vaccine, Dukoral, produced in Sweden, also contains several strains in addition to one of the toxin subunits.
Dukoral also protects against travellers’ diarrhoea.
Schedule
The course of immunization is:
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For people over six years old, two oral doses of the vaccine are given one week apart but no later than six weeks apart. A booster dose can be given two years after the first vaccination to maintain immunity.
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For children 2-6 years old, three oral doses of the vaccine are given at least one week apart but no later than six weeks apart. A booster dose can be given six months after the first vaccination to maintain immunity. The course of immunization should be finished at least one week before potentially coming into contact with cholera. Typically, this is one week before travel.
Dukoral is taken orally with bicarbonate buffer, which protects the vaccine from the gastric acid.
Side Effects
Oral cholera vaccine is well tolerated but side effects may include:
- Nausea, diarrhoea, vomiting, abdominal cramps
- Rarely joint pain, rash, numbness and tingling, and flu-like symptoms
