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Single-dose vaccine for cholera epidemic
December 17, 2017, 2:06 pm

More than three million cases of cholera are reported worldwide each year. The infectious disease is transmitted through food or water contaminated by the bacterium Vibrio cholera and hits developing countries particularly hard. The standard regimen for protecting against cholera with existing non-living oral cholera vaccines includes administering two doses over a two-week period. Now, researchers at the University of Maryland in the United States have found that giving a stronger single-dose of a live oral vaccine could be an effective tool in controlling outbreaks more quickly.

Researchers assessed the effectiveness (ability to stimulate vibriocidal antibody, an immune response that correlates with protection) of a single high-dose of live cholera vaccine CVD 103-HgR, which was developed by the university’s Center for Vaccine Development (CVD), versus the standard two-dose killed vaccine approach.

The research team found that the single-dose live oral vaccine approach could be the more effective way to rapidly protect individuals in large outbreaks of cholera. Given the highly encouraging results, the team envisions that as a matter of priority high-dose CVD 103-HgR will now be evaluated more completely in low income countries menaced by cholera.

Cholera transmission is endemic in many areas of Africa, Asia and the Caribbean. In severe cases, patients pass large amounts of diarrhea that causes rapid dehydration and ultimately death if left untreated. This year, the World Health Organization (WHO) estimated that in Yemen alone there have been a million cases of cholera.

Researchers will now study whether the single high-dose live vaccine is suitable for initiating vaccination campaigns early during outbreaks to nip them in the bud, as well as for preemptive vaccination to diminish the burden of expected seasonal increases of endemic cholera in countries where this disease persists as a public health problem. Also, since young children less than 5 years of age suffer the highest incidence of cholera but are less well protected than adults by the current two-dose oral killed vaccines, it will be important to assess the effectiveness of a single high-dose of CVD 103-HgR live vaccine in protecting young children.

The vaccine was approved in 2016 for use in the US by the Food and Drug Administration (FDA) for adults 18-64 years old traveling to regions where cholera is common. PaxVax, a global biotechnology company based in California, received marketing approval from the FDA for the vaccine, and CVD scientists have been working closely with PaxVax since 2009 to develop the vaccine and secure FDA licensure approval.

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