A vaccine developed by a US pharmaceutical company has been found to be 100% in preventing human infection with Ebola, its final clinical trial results have shown.
In a major human trial in Guinea, the vaccine gave doctors a safe and potent weapon against any future outbreak, the World Health Organisation said on Friday.
The vaccine is the first to prevent infection from one of the most lethal known pathogens, and the findings add weight to early trial results published last year.
The vaccine, called rVSV-ZEBOV, was studied in a trial involving 11,841 people in Guinea last year.
Among the 5,837 people who received the vaccine, no Ebola cases were recorded 10 days or more after vaccination, according to the results published in The Lancet journal.
In comparison, there were 23 cases 10 days or more after vaccination among those who did not receive the vaccine.
The trial was led by the WHO, together with Guinea's ministry of health and other international partners. "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 defenceless," said Dr Marie-Paule Kieny, WHO's assistant director-general for health systems and innovation, and the study's lead author.
Since Ebola virus was first identified in 1976, sporadic outbreaks have been reported in Africa. However, the 2013?2016 West African Ebola outbreak, which resulted in more than 11, 300 deaths, highlighted the need for a vaccine, WHO said.
The trial took place in the coastal region of Basse-Guinee, the area of Guinea still experiencing new Ebola cases when the trial started last year. The trial used an innovative design, a so-called "ring vaccination" approach - the same method used to eradicate small pox.
When a new Ebola case was diagnosed, the research team traced all people who may have been in contact with that case within the previous three weeks, such as people who lived in the same household, were visited by the patient, or were in close contact with the patient, their clothes or linen, as well as certain "contacts of contacts".
A total of 117 clusters (or "rings") were identified, each made up of an average of 80 people. Initially, rings were randomised to receive the vaccine either immediately or after a three-week delay, and only adults over 18 years were offered the vaccine.
After interim results were published showing the vaccine's efficacy, all rings were offered the vaccine immediately and the trial was also opened to children older than six years. The vaccine's manufacturer, Merck, Sharpe and Dohme, this year received Breakthrough Therapy Designation from the US Food and Drug Administration and PRIME status from the European Medicines Agency, enabling faster regulatory review of the vaccine once it is submitted.
(With inputs from PTI)