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Final trial results confirm Ebola vaccine provides 'high protection' – UN health agency

Ebola vaccine team at work in Katongourou, Guinea.
WHO/S. Hawkey
Ebola vaccine team at work in Katongourou, Guinea.

Final trial results confirm Ebola vaccine provides 'high protection' – UN health agency

The United Nations World Health Organization (WHO) has said that an experimental Ebola vaccine has been found to be highly protective against the deadly virus in a major trial in Guinea.

“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,” WHO said in a news release, noting the results of the latest trial, published earlier today in the medical journal The Lancet.

According to WHO, the vaccine, rVSV-ZEBOV was studied in a trial involving 11,841 people in Guinea during 2015. Among the 5,837 people who received the vaccine, no Ebola cases were recorded 10 days or more after vaccination. In comparison, there were 23 cases 10 days or more after vaccination among those who did not receive the vaccine.

“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' Assistant Director-General for Health Systems and Innovation, and the study's lead author.

The Ebola virus was first identified in 1976 and caused sporadic outbreaks in Africa. However, the 2013-2016 outbreak in west Africa, that killed more than 11,300 people, underlined the urgent need of a vaccine.

Guinea, along with Liberia and Sierra Leone, was one of the worst affected countries.

Noting the significance of the latest results, Dr. KeÏta Sakoba, the Coordinator of the Ebola Response and Director of Guinea's National Agency for Health Security, said: “Ebola left a devastating legacy in our country. We are proud that we have been able to contribute to developing a vaccine that will prevent other nations from enduring what we endured.”

'Ring vaccination' approach

The trial took place in the coastal region of Basse-Guinée, the area of Guinea still experiencing new Ebola cases when the trial started in 2015.

It employed an innovative design, a so-called “ring vaccination” approach – the same method used to eradicate small pox. This involved tracing all people who may have been in contact with a new Ebola case within the previous three weeks as well as certain “contacts of contacts.” These “rings” were randomized to receive the vaccine either immediately or after a three-week delay.

In addition to showing high efficacy among those vaccinated, the trial also shows that unvaccinated people in the rings were indirectly protected from Ebola virus through the ring vaccination approach. However, the authors note that the trial was not designed to measure this effect, so more research will be needed.

“This both historical and innovative trial was made possible thanks to exemplary international collaboration and coordination, the contribution of many experts worldwide, and strong local involvement,” said Dr. John-Arne Røttingen, specialist director at the Norwegian Institute of Public Health, and the chairman of the study steering group.

Also, WHO said that an international vaccine-focussed organization,GAVI, provided $5 million to Merck, one of the vaccine's manufacturers, towards its future procurement once the vaccine is approved, prequalified and recommended by WHO.

As part of this agreement, Merck committed to ensure that 300,000 doses of the vaccine are available for emergency use in the interim, and to submit the vaccine for licensure by the end of 2017. Merck has also submitted the vaccine to WHO's Emergency Use and Assessment Listing procedure, a mechanism through which experimental vaccines, medicines and diagnostics can be made available for use prior to formal licensure.