The World Health Organization (WHO) has confirmed that the VSV-EBOV Ebola vaccine on trial has been “highly effective” against the killer virus.
While more conclusive evidence is needed on its capacity to protect populations through what is called “herd immunity”, Guineans and the Guinean National Regulatory Authority and Ethics Review Committee have approved continuation of the trial.
The Guinea vaccination trial began in affected communities on 23 March 2015 to evaluate the efficacy, effectiveness and safety of a single dose of the vaccine VSV-EBOV by using a ring vaccination strategy. The strategy is such that all people who have come into contact with an infected person are vaccinated, creating a protective “ring” and stop the virus from spreading further. To date, over 4 000 close contacts of almost 100 Ebola patients, including family members, neighbours, and co-workers, have voluntarily participated in the trial.
Margaret Chan, director-general of WHO, said: “This is an extremely promising development. The credit goes to the Guinean Government, the people living in the communities and our partners in this project. An effective vaccine will be another very important tool for both current and future Ebola outbreaks.”
The next stage of the trail will include 13-17-year-olds and possibly six to 12-year-olds. “In parallel with the ring vaccination we are also conducting a trial of the same vaccine on frontline workers,” said Bertrand Draguez, medical director at Médecins sans Frontières.
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The test, backed by drug firm, Merck, the WHO and the governments of Canada, Norway and Guinea, saw 4,123 high-risk people vaccinated immediately after someone close to them fell ill with the deadly haemorrhagic fever. None of the vaccinated group caught the virus, according to study results published in The Lancet medical journal.
A second comparison group of 3,528 people received the vaccine only three weeks after potential exposure. Sixteen of them contracted the virus, said the study, but by day six after immunisation, the remainder of this group were also fully protected.