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New oral cholera vaccine highly effective during outbreak in Guinea

Cholera vaccines highly effective
Cholera vaccines highly effective
Centers for Disease Control and Prevention

An new oral vaccine against cholera was highly effective in preventing further cases in treated people during a recent cholera outbreak in Guinea, according to a new study, which is the first ever conducted during an actual outbreak in Africa.

Cholera is an infectious disease usually spread through contaminated water which causes severe diarrhea and dehydration. It is most common in countries which do not have proper sanitation or clean drinking water. Left untreated, cholera can be lethal in hours, even in healthy people. According to the World Health Organization, nearly half of the world’s cholera cases happened in Africa in 2012.

The study of the new vaccine was led by Epicentre, a research arm of the international medical humanitarian organization Doctors Without Borders. It is the first to show that this vaccine provides protection quickly, and can be used in the future to control outbreaks.

“Because we’d never documented the effectiveness of this new vaccine in real-life epidemic conditions, we didn’t have enough information to understand the potential of this vaccine as a tool to control a cholera outbreak,” said Francisco Luquero, principal investigator of the study. “Now we know that oral cholera vaccine confers a high level of protection in outbreak settings, and that vaccinating against this highly deadly disease can and should be one thing we do when we have a cholera epidemic on our hands, in addition to other preventive and control measures.”

The study looked at the effectiveness of of two complete doses of a type of WHO vaccine that is currently available, Shanchol, There is another cholera vaccine available, but Shanchol is considered more appropriate for developing countries because it is much more affordable, easier to produce, and easier to transport and keep in storage.

In the study, the Guinean Ministry of Health gave more than 300,000 doses of the vaccine in two rounds in two coastal districts experiencing cholera outbreaks. The vaccine, which is given in two doses, was given to between 75.8 percent and 75.9 percent of participants.

“We showed that with proper planning and outreach in the communities, it is indeed possible to vaccinate hundreds of thousands of people in a remote area with a highly mobile population and in a relatively short period of time,” said Dr. Iza Ciglenecki, project manager for the vaccination campaign in Guinea.

High coverage was found to reduce disease transmission in the vaccinated communities. Most of the confirmed cholera cases were from a small outbreak in a local community that had the lowest vaccination coverage. Suspected cholera cases were confirmed by rapid testing, and then teams confirmed how many of these people had been vaccinated. Vaccination with two complete doses of Shanchol was associated with a high rate of protection—86 percent—against cholera.

Shanchol was added to a WHO emergency vaccine stockpile. So far, the vaccine has not been commonly used as a public health tool for control of the disease. Concerns about its feasibility, timeliness, and acceptability by communities, as well as fear of diverting resources from other medical programs, have discouraged its use.

“The results, on both the effectiveness and feasibility of oral cholera vaccines during an actual emergency, will hopefully bolster efforts to integrate vaccines in the global response to cholera outbreaks,” said Dr. Rebecca Grais, senior author of the publication. But that could change.

“Until very recently, cholera vaccines have not been considered among the tools to use in outbreak control,” said Grais. “Several deadly and large-scale cholera epidemics have shown the limits of the traditional outbreak response to contain national-scale epidemics. The use of oral cholera vaccine should greatly improve our ability to prevent and control epidemics, and ultimately, to save more lives.”

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