Results of early tests of a new vaccine for Ebola shows it to be “highly effective,” the World Health Organization said Friday.
“This is an extremely promising development,” said Dr Margaret Chan, Director-General of the WHO. “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.”
Preliminary results from analyses of the interim data from the test were published Friday in the British journal The Lancet.
Since late 2013 when the latest epidemic began in West Africa, there have been 27,600 Ebola cases, including more than 11,000 deaths. Liberia has suffered the worst, with more than 4,800 deaths.
While the vaccine so far shows 100% efficacy in individuals, more conclusive evidence is needed on its capacity to protect populations through what is called “herd immunity,” according to WHO.
“Too many people have been dying from this extremely deadly disease, and it has been very frustrating for healthcare workers to feel so powerless against it,” said Dr. Bertrand Draguez, medical director for Médecins Sans Frontières.”More data is needed to tell us how efficacious this preventive tool actually is, but this is a unique breakthrough.”
He said that adding a vaccine to the fight against Ebola “will accelerate the break-up of transmission chains by targeting people who have been in contact with infected patients as well front line workers.”
At present, Draguez said, he suggested focusing on the target group would be more effecting than mass vaccinations, noting that the outbreak of the diseased is in localized communities, rather than nationwide in any country.
“The ‘ring’ vaccination method adopted for the vaccine trial is based on the smallpox eradication strategy,” said John-Arne Røttingen, Director of the Division of Infectious Disease Control at the Norwegian Institute of Public Health and Chair of the Study Steering Group. “The premise is that by vaccinating all people who have come into contact with an infected person you create a protective ‘ring’ and stop the virus from spreading further. This strategy has helped us to follow the dispersed epidemic in Guinea, and will provide a way to continue this as a public health intervention in trial mode.”
A new Ebola vaccine being prepared for injection for testing. The World Health Organisation is running phase III clinical trials for Ebola virus disease vaccine in Guinea. The technique being used is “ring vaccination” which was used in the 1970s to eradicate smallpox. (Photo: Sean Hawkey, WHO)
The Guinea vaccination trial began in affected communities in March to evaluate the efficacy, effectiveness and safety of a single dose of the vaccine VSV-EBOV by using a ring vaccination strategy. So far, more than 4 000 close contacts of almost 100 Ebola patients, including family members, neighbours, and co-workers, have voluntarily participated in the trial.
Mohamed Soumah, 27, was the first person to receive the Ebola vaccine. “It wasn’t easy. People in the village said that the injection was to kill me,” he said, according to a report by WHO. “I was afraid. I was the first one to be injected, the very first, here in my village (in March). I’ve been monitored for 3 months and I’ve had no problems. The last follow-up, 84 days after the vaccination, was all clear.”
The authors of the interim review in The Lancet said they believe the results of the trials “are also likely to be externally valid and
applicable to other regions of Guinea and to Sierra Leone and Liberia, the other two countries in west Africa most severely affected by the ongoing epidemic.”
The trial stopped randomization in late July to allow for all people at risk to receive the vaccine immediately, and to minimize the time necessary to gather more conclusive evidence needed for eventual licensure of the product, WHO said. Until now, 50% of the rings were vaccinated 3 weeks after the identification of an infected patient to provide a term of comparison with rings that were vaccinated immediately. This will now be ended. In addition, the trial will now include 13 to 17-year-old and possibly 6 to 12-year-old children on the basis of new evidence of the vaccine’s safety.