WHO to Launch Ebola Vaccine Efficacy Trial March 7

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The agency will employ a ring vaccination method similar to the one used to eradicate smallpox.


The World Health Organization (WHO) announced on March 5, 2015 that it will launch a Phase III trial on March 7, 2015 to test Merck and NewLink Genetics’ rVSV-EBOV Ebola vaccine in Guinea, which has the highest number of cases in the country. Trial participants will be selected based on who has had contact with newly diagnosed Ebola cases, a strategy know as ring vaccination that was used to knock out smallpox. Other, non-immediate contacts will be vaccinated three weeks later via a delayed ring. According to WHO, “This design allows for all contacts to be vaccinated by the end of the study, albeit with a short delay for some of them, rather than the standard alternative to use a placebo.”

The agency said immunizing the people in contact with the “index cases” of the virus, including frontline health workers, will help it assess the vaccine’s efficacy in those individuals. In addition, WHO hopes the vaccine will create a ring of protection against the virus. “An effective vaccine to control current flare-ups could be the game-changer to finally end this epidemic and an insurance policy for any future ones,” said assistant director-general Marie-Paule Kieny, who leads the Ebola Research and Development effort at WHO, in a press release.


The trial will be launched in collaboration with Médecins Sans Frontières, Epicentre, and The Norwegian Institute of Public Health, and will be supported by WHO, UNICEF, US Centers for Disease Control, the Global Vaccines Alliance, and the Bill and Melinda Gates Foundation. Earlier trials of rVSV-EBOV were funded by The Wellcome Trust.

The vaccine was originally developed by the Public Health Agency of Canada, but Newlink licensed the therapy to Merck last year. WHO also said a second vaccine candidate-GlaxoSmithKline’s cAd3-EBOZ, developed in partnership with the National Institute of Health’s National Institute of Allergy and Infectious Diseases Vaccine Research Center -“will be tested in a sequential study, as supply becomes available.”