The observational study carried out by 'Epicentre', the epidemiology and medical research center of Doctors Without Borders (MSF), published in the journal The Lancet Infectious Diseases, "shows, for the first time, that vaccination can halve mortality among people infected with Ebola".
The research was carried out in collaboration with the 'Institut National de Recherche Biomédicale (INRB)' and the Ministry of Health of the Democratic Republic of Congo (DRCongo) and analyzed data collected during the 10th Ebola epidemic in DRCongo, according to the MSF press release.
The investigation revealed that, "of the 2,279 confirmed Ebola patients admitted to a treatment center between July 27, 2018 and April 27, 2020, the risk of death was 56 percent for unvaccinated patients, but decreased to 25 percent for those who had received the vaccine".
This reduction in mortality applied to all patients, regardless of age or gender, as long as they were vaccinated, MSF said.
The study focused on the benefits of the rVSVΔG-ZEBOV-GP vaccine, the only Ebola vaccine recommended for use during an epidemic. It was designed to be administered in a single dose, they explained.
It was through a clinical trial carried out in Guinea-Conakry in 2017 that the vaccine demonstrated "very good protection against Ebola", but during the 10th epidemic in DRCongo, which borders Angola, some people who had been vaccinated before more than 10 days – the period considered sufficient to develop immunity – they contracted the virus.
"This fact highlights the importance of describing the effectiveness of the vaccine, not only against infection, but also its impact on mortality", they stressed.
"Vaccination after exposure to a person infected with Ebola, even when administered shortly before the onset of symptoms, continues to provide significant protection against death," explained an epidemiologist at 'Epicentre', Rebecca Coulborn, quoted in the statement.
This study provided "further evidence of the importance of Ebola vaccination during epidemics that occur regularly in sub-Saharan Africa", which are often caused by the 'Zaire Ebola virus' species, which is associated with high mortality. Since 2019, two vaccines, rVSVΔG-ZEBOV-GP and Ad26.ZEBOV/MVA-BN-Filo, have obtained prequalification from the World Health Organization (WHO) against this strain, according to MSF.
