New Ebola vaccine field trial shows up to 100% efficiency

An Ebola vaccine developed by the Public Health Agency of Canada and tested in Guinea has turned out to be almost 100 percent effective, the World Health Organization said Friday, citing the British medical journal The Lancet.

The researchers used the newly-developed Ebola shot in so-called ring vaccination, the method that helped eradicate smallpox in the past. It is based on vaccination of all people who came into contact with an infected person, creating a so-called “protective ring” that prevents the disease from spreading.

More than 7,000 adults were included in 90 clusters to take part in the study. About 4,000 of those involved were assigned to immediate vaccination after confirmation of the contact with an infected person and about 3,000 others to delayed vaccination 21 days after the contact. Pregnant and breastfeeding women were excluded from the test.

In the period between April 1 and July 20, more than 3,500 people were vaccinated. As a result, no patient got sick with Ebola after immediate vaccination whereas 16 people got sick among those who got delayed vaccination. In other words, current findings show near-100 percent efficiency of the vaccine.

"This is an extremely promising development," said Margaret Chan, Director-General of the World Health Organization, in a statement. "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.”

Jeremy Farrar, director of the Wellcome Trust, one of the funders of the trial, was cited as saying by the WHO: "This is a remarkable result which shows the power of equitable international partnerships and flexibility.”

Guinean authorities, the WHO, Médecins sans Frontières (MSF) and the Norwegian Institute of Public Health supported by various national and international organizations continue the trial. According to Reuters, delayed vaccination has not been used since July 26 because of “unethical and unnecessary risk.” Teenagers from 13 to 17 years old will now also be vaccinated due to the vaccine’s proven safety.

The latest Ebola outbreak started in early 2014 and embraced, primarily, three West African countries: Sierra Leone, Liberia and Guinea. Up to July 26, there were 27,784 registered cases and 11,294 people died from the virus, the WHO reports.