The World Health Organization (WHO) confirmed on Friday that the Ebola virus vaccine called rVSV-ZEBOV was highly protective against the deadly virus in a major trial in Guinea. WHO officials said that this new breakthrough of the vaccine adds weight to early trial results published last year.

Here are three fast facts about the recent findings on the Ebola vaccine.


1. The Ebola vaccine is the first to prevent infection from one of the most lethal known pathogens of Ebola virus.

The study entitled as “Efficacy and effectiveness of an rVSV-vectored vaccine in preventing Ebola virus disease: final results from the Guinea ring vaccination, open-label, cluster-randomised trial” was published in The Lancet. It revealed that the vaccine rVSV-ZEBOV was tested among 11,841 people in Guinea during 2015.

The study was headed by WHO’s Assistant Director-General for Health Systems and Innovation Dr. Marie-Paule Kieny, who was joined by more than 10 colleagues and the participation of Guinea’s Ministry of Health. The team conducted the trial and found out that among the 5,837 people who received the vaccine, no Ebola cases were recorded 10 days or more after vaccination.

2. The Ebola vaccine was tested through a “ring vaccination” approach, which was conducted in Basse-Guinée, Guinea.

WHO said that this approach is similar to the method used to eradicate small pox. In using this method, the team immediately traced all people who may have been in contact when a new case of Ebola virus disease appeared.

To assess safety, people who received the vaccine were observed for 30 minutes after vaccination, and at repeated home visits up to 12 weeks later. WHO noted that the vaccine was effective as half of the participants reported mild symptoms of a headache, fatigue and muscle pain soon after they received the vaccine.

3. The Ebola vaccine’s manufacturer is Merck, Sharpe & Dohme.

The manufacturer received a Breakthrough Therapy Designation from the United States Food and Drug Administration (FDA) and PRIME status from the European Medicines Agency. This allowed faster regulatory review of the vaccine once it was submitted.

WHO noted that the trial’s success was due to its strong collaboration and support with the following international agencies:

  • Wellcome Trust
  • United Kingdom Department for International Development
  • Norwegian Ministry of Foreign Affairs
  • Norwegian Institute of Public Health through the Research Council of Norway
  • Canadian Government through the Public Health Agency of Canada
  • Médecins Sans Frontières.

“While these compelling results come too late for those who lost their lives during West Africa's Ebola epidemic, they show that when the next Ebola outbreak hits, we will not be defenseless,” Kieny said in a statement.

According to the latest WHO data, a total of 28,616 Ebola cases has been reported in Guinea, Liberia and Sierra Leone, with 11,310 deaths. At present,  over 10,000 people are survivors of Ebola virus disease.

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