The first real-life trial of the oral cholera vaccine Shanchol has been deemed safe to use and viable for protection against the disease. Results reveal that severe life-threatening cases of cholera was reduced by nearly 40% among those vaccinated.
The study, published in The Lancet, examined the drug’s effectiveness in urban Bangladesh where the disease is endemic. The findings represent a huge step toward controlling outbreaks and developing effective mass vaccination programs.
The drug is one of two internationally licensed cholera vaccines currently available. Cholera vaccines are not a new development and have been used to protect travelers from Western countries for more than a decade, but never have they been used for widespread control of the disease in an endemic region.
Although the vaccine is effective, easy to administer and relatively inexpensive to produce, it has never been tested on a mass group in real-life conditions until now. The study included almost 27,000 residents aged one year and older from the urban slums of Mirpur, in the city of Dhaka. The area poses an extremely high risk of cholera infection in the area due to overcrowding and poor sanitation.
Researchers conducted a double-blind, cluster-randomized, placebo-controlled trial. Residents were prescribed one of the following:
- An oral cholera vaccine
- An oral cholera vaccine plus behavioral change program to improve hand-washing and to provide clean drinking water
- No intervention at all.
The vaccine was administrated in two doses 14 days apart through routine government health services, and the publicity campaign for vaccination was well accepted by the local community. However, just over half of the residents in the two intervention groups received the complete number of doses.
Despite this, the vaccination showed promising results. The overall incidence of severely dehydrating cholera fell by 37% after two years in the vaccination group and by 45% when used in combination with the hand washing and clean drinking water program.
Analysis of individual protection showed the vaccine gave 53% protection against cholera during the two-year follow-up.
There were no serious adverse effects from the vaccine; the majority of reactions were mild or moderate. The most common were acute watery diarrhea, vomiting, abdominal pain and fever. Lead author Dr. Firduausi Qadri from the International Centre for Diarrhea Disease Research, Bangladesh, hopes the findings act as a springboard for future development:
“Our findings show that a routine oral cholera vaccination program in cholera-endemic countries could substantially reduce the burden of disease and greatly contribute to cholera control efforts. The vaccine is cheap: two doses cost US $3.7, around a third of the price of the other licensed vaccine Dukoral.”
Worldwide, cholera affects 3-5 million people, and over 1 billion are estimated to be at risk of disease. The disease remains a danger in more than 50 countries where it is endemic such as Bangladesh. Although the results of the study are promising, Dr. Qadri believes a vaccine is only part of the solution. She explains:
“Ultimately, the key to controlling cholera is clean water and adequate sanitation, which half the developing world (around 2.5 billion people) lack, but this remains a rather difficult reality for the world’s poorest nations as well as those affected by climate change, war and natural disaster.”
Earlier this year, the Nepal Earthquake caused millions to be at risk of a cholera outbreak in the aftermath of the disaster.
Maureen O’Leary and Kim Mulholland from the London School of Hygiene & Tropical Medicine, echo Dr. Qadri’s comments, saying a vaccine should “not supersede efforts to reduce risky behaviors.”
Cholera is a diarrheal illness caused by the bacteria Vibrio cholera and most commonly enters the human ecosystem through contaminated water or food. If untreated, the disease can have high fatality rates, especially among young children and babies. The cholera epidemic in parts of Africa has been ongoing for more than 30 years, due to inadequate sanitation and water treatment systems.