Amidst Ebola Outbreak, Experimental Vaccine Shows Promise

Amidst Ebola Outbreak, Experimental Vaccine Shows Promise

The World Health Organization (WHO) announced on May 12 that an outbreak of the Ebola virus has occurred in the Democratic Republic of Congo (DRC), posing a threat to hundreds of civilians. [1,2]  So far, 20 suspected cases have been reported, resulting in three deaths including the initial case involving a 45-year-old man who died six days after initially seeking help on April 22. [3]  The cases remain centered around Bas-Uele, a northeastern province of the country bordering the Central African Republic; while currently contained to this area, the aggressive nature of the Ebola virus means it poses a significant threat to surrounding regions. [1,3]

Peter Salama, the Executive Director for Health Emergencies at WHO, stated that the outbreak is only a low-level threat on a global scale. [1] However, the risk assessment is high at the national level and medium at the regional level, with the potential to greatly affect residents of Bas-Uele and nearby regions. [1] The most recent outbreak prior to this instance, which occurred in 2014, also took place in Bas-Uele and killed 49 people in 3 months. [2] Although the death count remains low for the current outbreak thus far, the number of casualties could quickly escalate to the levels seen in the previous incident. Salama noted that although the DRC has “a proven track record of [effectively] managing Ebola outbreaks,” it is still important to “never, ever underestimate the Ebola virus disease.” [1,4]

With this cautionary perspective in mind, the WHO has taken steps to reduce the threat of a large-scale outbreak and to prevent further transmission of the virulent disease. In addition to conventional containment and management methods, which include following up on roughly 400 cases of close contact and educating local communities on ways to prevent the spread of disease, the WHO is hoping to introduce vaccinations in order to combat Ebola outbreaks in the DRC and beyond. [3] 12 different Ebola vaccines are in development, but all are still in the experimental phase, undergoing review by the FDA and other regulatory agencies, and are not for sale commercially. [2,3,5] However, on April 17, WHO’s advisory group on immunization strongly recommended that, in addition to other intervention techniques, the experimental vaccine rVSV-SEBOV be deployed in the event of an Ebola outbreak. [5]

The rVSV-SEBOV vaccine, developed by the Public Health Agency of Canada, has been shown to be highly effective and safe in a 2015 study in Guinea. [2] In this trial, none of the 5,837 individuals who received the vaccine developed Ebola within ten days after vaccination, despite the emergence of 23 cases amongst those who had not received the vaccine. [2] The WHO remains confident that the vaccine will show similarly positive results if used in the DRC, as the strain of the Ebola virus currently present in the DRC - the Zaire strain - is the same one used in the rVSV-SEBOV vaccine. [3] Still, the National Regulatory Authority in the DRC, a group responsible for ensuring that publically distributed products meet international quality and safety standards, must first make the decision to allow for the use of vaccines in order for the WHO’s plans to be implemented. [1,6] Because the vaccine is not currently approved for commercial use, distribution and vaccination must follow the protocol of a study, which includes ethical oversight and the informed consent of all participants. [3] Furthermore, the WHO plans to administer the vaccine in a “ring vaccination” design, meaning it will only be given to those in close contact with known or suspected Ebola cases rather than the general public. [1,3] Through this approach, the WHO hopes it will be able to effectively prevent the spread of the disease while limiting the risks of using an experimental vaccine by restricting it to a smaller number of people.

The WHO is working to provide an immediate response so that if authorities decide to proceed, a sufficient supply of rVSV-SEBOV will be ready right away. The manufacturer of the drug, Merck, currently has 700,000 doses ready in the US, and the Global Alliance for Vaccines and Immunization (GAVI) purchased 300,000 units from Merck to use for future outbreaks. [2,3] Commenting on the plans for shipment of the vaccine, the WHO’s Regional Director for Africa, Dr. Matshidiso Rebecca Moeti, stated that the WHO is “putting all these preparations in place so it can go at that speed as soon as we get the green light.” [1] With these preparations, as well as adherence to standard containment protocols, the WHO hopes to quickly stop the spread of the disease in the DRC: “I’m very optimistic it is going to get us to where we’d like to be: a controlled, short-lived outbreak of Ebola as they have seen in the past in this country,” commented Dr. Moeti. [1]

 

Sources

  1. Samuelson, Kate. “Ebola is Back. Here Are the Challenges Ahead.” TIME. Published May 18, 2017. http://time.com/4784029/ebola-outbreak-congo/

  2. Maxmen, Amy. “Ebola vaccine could get first real-world test in emerging outbreak.” Nature. Published May 12, 2017. https://www.nature.com/news/ebola-vaccine-could-get-first-real-world-test-in-emerging-outbreak-1.21989

  3. Cohen, Jon. “As Ebola outbreak grows, question of using vaccine becomes more urgent.” Science. Published May 18, 2017. http://www.sciencemag.org/news/2017/05/ebola-outbreak-grows-question-using-vaccine-becomes-more-urgent

  4. Soucheray, Stephanie. “WHO: Ebola vaccine could be deployed within a week.” University of Minnesota Center for Infectious Disease Research and Policy. Published May 18, 2017. http://www.cidrap.umn.edu/news-perspective/2017/05/who-ebola-vaccine-could-be-deployed-within-week

  5. Muanya, Chukwuma, et al. “WHO may deploy Ebola vaccine for first test in DRC.” The Guardian. Published May 18, 2017. https://guardian.ng/news/who-may-deploy-ebola-vaccine-for-first-test-in-drc/

  6. “National Regulatory Agencies.” The World Health Organization. http://www.who.int/immunization_standards/national_regulatory_authorities/role/en/

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