The vaccine was tested in a trial involving nearly 12,000 people in Guinea and Sierra Leone during 2015 and 2016. Among the 5,837 people who got the vaccine, no Ebola cases were recorded. By comparison, there were 23 Ebola cases in the control group that had not gotten the vaccine.And remember vaccines don't have to be 100% effective to prevent epidemics. So it seems likely that Ebola is finished as a major health threat, unless war or some similar catastrophe leads to a complete public health breakdown.
“This trial, confirming the 100 percent efficacy of the rVSV Ebola vaccine, is a simply remarkable outcome,” Dr. Jeremy Farrar, the director of the Wellcome Trust, said of the research. “We’ve shown that by working collaboratively, across international borders and sectors, we can develop and test vaccines rapidly and use them to help bring epidemics to an end.”
This is fascinating:
When they launched the trial in 2015, the number of Ebola cases in Guinea had already declined, and there were too few cases to run a meaningful traditional randomized study (giving the vaccine to a randomly selected group and comparing it with a control group that doesn’t get the vaccine). So the researchers had to be creative. They decided to try something called “ring vaccination,” a public health method used to eradicate smallpox in the 1970s. It involves immunizing the immediate contacts — friends, family, housemates, neighbors — of a person who falls ill with a virus to create a protective ring around them to stop transmission.Sometimes human cleverness amazes me.
As soon as a new Ebola case was diagnosed, the researchers traced all their contacts for a total of 117 clusters (or “rings”), each made up of about 80 people. They then randomized the rings of people to get the vaccine either right after their friend or family member had been diagnosed or after a three-week delay.
Their preliminary results were so positive that the researchers changed the trial design so that everyone got the vaccine immediately, including children.