The Ebola vaccine helped reduce the risk of infection as well as the mortality of people infected with this serious disease, according to a study conducted by Epicenter, a branch of Médecins Sans Frontières (MSF).
- A new study shows for the first time that vaccination can halve mortality among people infected with Ebola.
- The rVSVΔG-ZEBOV-GP vaccine reduces the risk of death by half.
- No antagonistic effect between vaccination and Ebola treatments was observed during this research.
Ebola virus disease (formerly also called Ebola hemorrhagic fever) is a rare disease, but particularly dangerous for humans. According to figures from the Pasteur Institute, its lethality rate is between 30 and 90% depending on the epidemics and the viral species involved. Researchers have worked for years on developing a vaccine.
The single-dose rVSVΔG-ZEBOV-GP vaccine proved particularly effective during the 10th Ebola epidemic in the Democratic Republic of Congo (DRC), according to an observational study conducted by Epicenter, a branch of Médecins Sans Frontières (MSF): beyond reducing the risk of Ebola virus infection, vaccination can reduce the mortality of patients by half.
Ebola vaccine: half the risk of dying
Researchers analyzed data collected in an Ebola treatment center during the circulation of the virus in the DRC between July 27, 2018 and April 27, 2020. Of the 2,279 infected patients treated, the risk of death was 56 % for unvaccinated patients and fell to 25% among those who had received the vaccine. Vaccinated patients therefore have a much lower risk of dying from the disease. “This reduction in mortality applied to all patients, regardless of their age and gender”add the communicated.
In addition, the results, presented in the review The Lancet Infectious Diseases, showed that the vaccine protects against the risk of death, even when people have received the dose “tardily”. That is to say after being exposed to Ebola virus disease. The researchers also recorded no antagonistic effect between vaccination and treatments against the disease.
“Vaccination after exposure to an Ebola-infected person, even when administered shortly before symptoms appear, still confers significant protection against death”explains Rebecca Coulborn, epidemiologist at Epicenter. “The reduction in this risk is added to that due to the specific treatment of Ebola, regardless of the time before treatment.”
Ebola: a vaccine recommended for people at high risk
The rVSVΔG-ZEBOV-GP vaccine is administered in a single dose. In 2019, the latter obtained prequalification from the WHO for use against the Zaire Ebolavirus strain, which is associated with high mortality.
The injection is recommended for people at high risk of exposure during outbreaks. That is to say the contact cases of a person infected with the Ebola virus, the contacts of these contacts and health and/or front-line personnel.
“In addition to the direct benefit, our results allow us to consider combining vaccination and treatment of patients who have been in direct contact with a person for whom the diagnosis of Ebola has been confirmed, in order to reduce the risk of illness and of deceased”concludes Etienne Gignoux, director of the epidemiology and training department at Epicenter.
Another vaccine against Ebola, called Ad26.ZEBOV/MVA-BN-Filo, also obtained the green light from the WHO 4 years ago.