Ebola vaccine seems effective
Canadian creation could stop outbreak, prevent disasters, but still needs approval
On Friday, a World Health Organization official issued a statement it has never uttered before: “We believe that the world is on the verge of an efficacious Ebola vaccine.”
The words were spoken by Dr. Marie-Paule Kieny at a news conference, where she announced the interim results from a clinical trial of VSV-ZEBOV, the experimental Ebola vaccine developed by Canadian scientists.
Citing a new study published in the Lancet medical journal, Kieny said the vaccine was 100 per cent protective when given immediately to more than 4,100 people in Guinea who came into close contact with an Ebola patient. Although Kieny emphasized the results’ preliminary nature — more investigation is needed before conclusions can be drawn — she acknowledged the vaccine could become the world’s first effective weapon in the fight against Ebola.
“It could be a game changer indeed,” said Kieny, who is the WHO’s assistant director general of health systems and innovation. “Because previously there was nothing against Ebola, in spite of this disease having been identified 40 years ago.”
The apparent success of the madein-Canada vaccine is an unprecedented development in what has been an unprecedented public health disaster.
Ebola was first detected in Guinea in March 2014 and the outbreak was deemed a global health emergency by the WHO almost exactly one year ago. Although only a handful of infections remain, even a single case can reignite the outbreak. The virus infected more than 27,700 people, of which 11,294 have died.
VSV-ZEBOV has long been considered one of the two leading candidates in the race for an Ebola vaccine. The other is a GlaxoSmithKline product. The Canadian vaccine, licensed to Merck, was developed 13 years ago by scientists with the Public Health Agency of Canada.
“It’s the day we were waiting for,” said Dr. Heinz Feldmann, who spearheaded the vaccine’s early development at the PHAC’s lab in Winnipeg before relocating to the United States in 2008. “To be honest, I wasn’t sure if I ever would have expected this to happen during my active (career) time.”
Even if the vaccine never reaches market, it can be considered an extraordinary achievement. Reaching this point involved “superhuman” effort by a sprawling network of agencies and governments, said Dr. Ross Upshur, a University of Toronto professor and member of the WHO’s ethics panel for Ebola vaccines.
The speed of the work was unprecedented and the vaccine trials managed to get ethics approval and field results in less than a year. “These things typically take a long time, five to seven years,” Upshur said. “This is a remarkable achievement.”
The study’s “ring vaccination” design — first employed to eradicate smallpox — has also never been used before in a clinical trial.
With every new case of Ebola, responders moved in to vaccinate everyone in that person’s family and social circles, thus creating a protective “ring” of immunity.
Kieny said the clinical trial is continuing even though the interim results were good enough to eliminate the delayed vaccination group. Every contact will now be inoculated when anew Ebola case is detected, she said.
But many questions need to be answered before this vaccine can be used more widely: How long does immunity last? Should the vaccine be given to entire populations — or just targeted communities when outbreaks emerge?
It is also unclear whether drug regulators, who have to be reassured of a new vaccine’s safety before signing off on it, will accept these findings from such an unorthodox study conducted under unprecedented circumstances, Upshur said.