Preliminary results from the Norwegian-led trial underway in Guinea, published in the UK medical journal The Lancet, indicate that the vaccine may provide complete protection against Ebola virus disease.
The vaccine study is a collaboration between the public health authorities in Guinea, the World Health Organization (WHO), Doctors Without Borders/Epicentre and the Norwegian Institute of Public Health. The pilot phase of the trial began in late March 2015 and thus far the study has recruited roughly 4 000 trial participants.
John-Arne Røttingen, Director of the Division of Infectious Disease Control at the Norwegian Institute of Public Health and head of the study’s steering committee, says, “The initial results give us reason to believe this could be the world’s first effective Ebola vaccine ever developed.”
GLOBVAC programme very pleased
“We are very pleased that the results thus far are so encouraging,” says Programme Coordinator of the GLOBVAC programme Åse-Marit Kristiansen. “An effective Ebola vaccine would save many lives.”
“This is a prime example of the importance of strong initiatives in the field of global health and vaccination research as well as of international cooperation in this field,” she adds.
Vaccinating in a ring
The trial employs a “ring vaccination” design that vaccinates a ring of people around new Ebola cases, typically around and including the village or neighbourhood in which the infected person lives.
A randomly selected half of these rings were given the vaccine immediately, while the other half of the rings received the vaccine 21 days later.
The number of infected cases among those immediately vaccinated was then compared to the number of cases identified in the group with delayed vaccination. This enabled researchers to measure the protective effect of the vaccine, while at the same time ensuring that all participants were offered the vaccine, as required under the trial.
Ring vaccination was employed in the campaign to eradicate smallpox in the 1970s but has never before been used in clinical trials.
Immediate vaccination may give full protection
“None of the participants who received immediate vaccination have become ill so far,” says Dr Røttingen. This could indicate that the vaccine provides complete protection against Ebola. In the control group, by contrast, where participants received the vaccine 21 days later, there were several Ebola cases.
In light of these promising results, an independent committee in charge of monitoring participant safety and the trial outcomes has concluded that it is unethical to continue delaying vaccination. The committee thus recommends that the trial offer vaccines immediately to all those in contact with Ebola-infected people.
“From a strictly scientific point of view we would want more solid data,” explains Dr Røttingen, “but from a public health perspective as well as for ethical reasons we in the steering committee along with WHO have decided to proceed with immediate vaccination of all rings and to publish the interim results.”
Guinea badly affected
Guinea is one of the West African countries most severely affected by the Ebola epidemic. As of the beginning of July 2015 over 11 000 people have died from the disease in West Africa, some 2 500 of them in Guinea.
The continuation of the trial could help to control the still ongoing outbreak in Guinea, and ring vaccination could be relevant for new cases in Sierra Leone as well.
The trial is being funded by the Norwegian Ministry of Foreign Affairs through allocations via the Research Council, as well as by the Wellcome Trust and the Canadian health authorities. In addition, Doctors Without Borders, WHO and the Norwegian Institute of Public Health have invested considerable resources.
Dr Røttingen says the Ebola vaccine will most likely be licensed and available on the market at the earliest in 2016, once necessary approval procedures have been carried out. Recommendations on use are determined by the WHO Strategic Advisory Group of Experts (SAGE), and implementation is determined by the health authorities in each country. The vaccine will most likely be used in ring vaccination in future Ebola outbreaks.
(This article is primarily based on the Norwegian Institute of Public Health press release published on 31 July 2015.)