What is Cholera?
Cholera is a disease caused by bacteria Vibrio cholerae that leads to acute diarrhoea in the infected person1. It is known as a “food-and-water-borne” disease. Poor hygiene, limited access to clean drinking water and food, contributes to the outbreak of this disease.
Cholera outbreaks normally occur during emergency situations such as floods, war or an earthquake, when hygiene and sanitation gets compromised. According to the World Health Organisation, there are between 3–5 million cholera cases and 100,000–120,000 deaths every year, of which only a few are officially reported2.
Cholera affects both adults and children and may take 12 hours to 5 days for a person to present symptoms after coming in contact with the bacteria through food or water3. Symptoms of cholera include watery diarrhoea with severe dehydration, which can be fatal if not treated on time3.
Where is Cholera found?
Cholera is an ancient disease dating back to the era of BC. During the 19th century, Cholera spread throughout the world from its original place near the Ganga river basin in India3. Today, majority of Cholera cases is found in Africa (44%) and Haiti alone (45%)4. The WHO statistics reported over 2000 deaths worldwide in 2013 due to cholera4. Other places where Cholera outbreak is commonly seen is Asia, South and Central America.
What is a Cholera Vaccine?
A cholera vaccine is a medicine that helps prevent cholera infection in healthy people. Previously, injectable whole-cell cholera vaccines were developed and extensively used in India in the 20th century, which have now been abandoned due to their limited effectiveness and adverse events1. Currently, there are 2 WHO pre-qualified oral vaccines. Both these vaccines require 2 doses for full protection3.
One of the killed types of cholera vaccine was licensed in 1991 and is used by travellers visiting regions where cholera is wide-spread. Another less expensive modified killed whole-cell OCV (oral cholera vaccine), which was first licensed in India in 2009 was later modified by the WHO in 20111.
Both these WHO-prequalified OCVs, have been deployed in mass vaccination campaigns across many endemic regions such as Haiti, Indonesia, Uganda, Mozambique, Tanzania, India, Bangladesh, South Sudan, Malawi, Thailand, Ethiopia and Nepal1.
People who take cholera vaccines have approximately 65% protection against the disease for up to 5 years3. Moreover, a reduced circulation of the bacteria in the endemic areas further reduces the chances of infection in general population3.
Cholera vaccine recommendations:
- Recommended only for the vaccination of persons residing in highly endemic areas and travelling to areas where risk of transmission is very high
- Not recommended for routine use in healthy people
What is the schedule for Cholera Vaccine6?
1) Primary immunisation
- Children >1 year old - 2 doses can be given 2 weeks apart.
- Adults and children over 6 years of age: two doses of oral vaccine are given with a 1- to 6-week interval.
2) Booster Dose
- Children aged 2-6 years: A booster dose should be given within six months of the primary course.
- Adults and children over 6 years of age: A booster can be given within two years after the primary course. If more than two years have elapsed since cholera vaccination, the primary course must be repeated.
How effective is the vaccine?
The oral cholera vaccine is considered safe and provides good protection against cholera. The oral cholera vaccines that are presently available, can prevent up to 50-60% of cholera episodes up to 1st 2 years after the primary vaccination.
Are there any side effects?
Side effect due to Cholera vaccine is extremely rare. Only 1 person in 100 people may develop some form of diarrhoea or stomach pain or nausea for a short time after taking the vaccine7.
The safety profile in pregnant ladies and breast feeding mothers is still not established; hence this vaccine should be taken by pregnant & lactating women only if they live in the high-risk areas where infection is quite rampant7.
What if a dose is missed?
It is recommended that children up to 2-5 years of age should be given 3 doses of cholera vaccine, each dose should be spaced up to 1-6 weeks apart. However, if 6 weeks pass since the last dose of vaccine, full vaccination course must be restarted.
- PLoS Negl Trop Dis. 2016 Dec; 10(12): e0005124. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5145138/
- WHO. Cholera, Fact sheet No. 107. Geneva: 2012 Contract No.: 12 August 2013. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4540465/#pone.0135676.ref01
- PLoS One. 2015; 10(8): e0135676. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4540465/#pone.0135676.ref01
- Immunisation against infectious disease - the Green Book (latest edition); Public Health England https://patient.info/in/doctor/cholera-and-cholera-vaccination
- Cochrane Database Syst Rev.2011 Mar 16;(3):CD008603.