No Ebola cases were recorded 10 days or more after vaccination was introduced among the nearly 6,000 people, who received the vaccine.

CCTV’s Leslie Mirungu reports. 

The rVSV-ZEBOV vaccine developed by Merck was tried in Guinea, which was still seeing new Ebola cases when the trial started in 2015.

“What we have shown is that in the vaccinated people we have had zero case of Ebola, while, at the same time, we have had 23 cases in the people who were not vaccinated with Ebola,” Dr Marie-Paule Kieny, assistant-director general for the WHO said.

“So you compare zero to 23, and you can calculate that you have a vaccine which has shown a 100 percent efficacy. Of course, you know, in a larger group, it could be that it is not a 100, it could be 80 percent, 90 percent, but this still shows that the vaccine is highly efficacious.”

The trial used a “ring vaccination” approach. Under it, researchers traced all people who might have been in recent contact, when a new Ebola case was diagnosed. They then logged them as clusters and administered the vaccine immediately.