A newly developed vaccine against the deadly Ebola virus is “highly effective” and could help prevent its spread in the current and future outbreaks, the World Health Organization said Friday.
Trials of the single-dose VSV-EBOV vaccine began in March in Guinea — one of three West African nations at the center of the outbreak — and have shown such promise that this week it was decided to extend immediate vaccination to “all people at risk” after close contact with an infected person, a WHO news release said.
“This is an extremely promising development,” said Dr. Margaret Chan, the body’s director general.
“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.”
More research is needed, but the results so far on this trial show 100% efficacy.
It will take weeks at the least, and possibly a couple of months, for more supply to be made, according to Chan.
Researchers have been using a “ring” strategy — based on that used in smallpox eradication — to trial the vaccine’s effectiveness.
“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,” said John-Arne Rottingen, of the Norwegian Institute of Public Health, which has been involved in implementing the trial.
Relatives, co-workers, health workers get jab
To date, more than 4,000 close contacts of almost 100 Ebola patients, including family members, neighbors and co-workers, have voluntarily participated in the trial, the WHO news release said.
Until this week, half were vaccinated three weeks after the identification of an infected patient and others straight away, to allow for comparison of the results. The randomization was stopped on July 26 “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,” the WHO said.
The trial will now include 13- to 17-year-olds, and possibly children from the age of 6, on the basis of new evidence of the vaccine’s safety, it added.
The vaccine is also being trialled by front-line health workers, said Medecins sans Frontieres, also known as Doctors without Borders.
The VSV-EBOV vaccine was developed by the Public Health Agency of Canada and licensed to Merck and NewLink.
The Guinea trial is being implemented by the Guinean authorities, the WHO, MSF and the Norwegian Institute of Public Health, with support from a range of international and national organizations.
The concerted effort to find a vaccine reflects the severity of the crisis presented by Ebola, spread through contact with body fluids from an infected person or contaminated objects from infected persons. Other vaccines are also being trialled.
WHO: Lowest weekly total in over a year
More than 11,000 people have died in the three worst-affected countries — Guinea, Sierra Leone and Liberia — since the epidemic took hold last year.
While the number of new Ebola cases is now far below that at the peak of the outbreak, it has remained stubbornly difficult to eradicate.
On July 26 the WHO reported seven Ebola cases were confirmed in the preceding week, four in Guinea and three in Sierra Leone.
“This is the lowest weekly total for over a year, and comes after 8 consecutive weeks during which case incidence had plateaued at between 20 and 30 cases per week,” the WHO said.
Two people in Liberia, including a 17-year-old in Nidonwin, Liberia, have died of Ebola since the end of June, just weeks after the WHO declared the nation free of the disease. At the time, though, officials did warn that outbreaks in Guinea and Sierra Leone ran the risk of bringing the virus back to Liberia, where more than 4,000 people died after contracting it.
All 33 contacts in Liberia who are being followed up in the study are two days from completing the 21-day period to be declared free of the disease.