Testing is scheduled to begin this week on a promising Ebola vaccine co-developed by the National Institutes of Health (NIH) and GlaxoSmithKline (GSK).

The candidate drug is based on an attenuated strain of a chimpanzee cold virus, which is used as a carrier to deliver benign genetic material derived from a strain of the Ebola virus. The material contained in the vaccine does not cause an infection, but instead delivers viral genetic material to human cells without further replication allowing the recipient’s cells to express a protein that generates an immune response.

“On short notice, the project partners have contributed enormous energy, time, and resources to respond to the Ebola disease calamity,” said director of the University of Maryland School of Medicine Center for Vaccine Development Myron Levine in a press release. “If the vaccine trials begin according to schedule, a new paradigm will have been established whereby multiple agencies mobilize to address a public health threat by accelerating the preliminary evaluation of a promising potential public health tool.” 

The vaccine will initially be given to 3 healthy subjects to assess potential side effects. If the drug passes safety testing, researchers will evaluate its efficacy in generating an immune response. A study arm in the United Kingdom will include 60 healthy volunteers, while separate arms in Gambia and Mali will each involve 40 volunteers who will be split into groups of 20.

Those groups will receive different doses of the vaccine to evaluate the best dosage amount in terms of safety and efficacy. The phase 1 trials are anticipated to conclude by the end the year, while deployment of the drug could be fast-tracked if the vaccine is determined to be safe and immunogenic, the NIH said.

The NIH is also working with Thomas Jefferson University in Philadelphia to develop an Ebola drug based on a rabies virus vaccine that has been found to protect animals against rabies and Ebola infection, the organization said in a press release. Researchers are investigating an inactivated version of the drug for human and veterinary use, in addition to a live vaccine to be tested in African wildlife in an attempt to prevent the transmission of Ebola from animals to humans.

The World Health Organization (WHO) said last week that the Ebola virus could infect more than 20,000 people in West Africa before the outbreak is brought under control. To date, the virus has killed more than 1500 people, with more than 3000 confirmed and suspected cases, according to the WHO.

Last week, Senegal became the fifth country in West Africa where the disease has spread after a 21-year-old student from Guinea was placed in quarantine following a confirmed infection, according to CNN.

“This epidemic has shown how difficult it can be to control Ebola,” said Jeremy Farrar, director of the Wellcome Trust, in a press release. “How useful drugs and vaccines might be in complementing existing public health interventions can only be assessed in epidemics.”