The results of an observational study show for the first time that ‘Ervebo’, the Ebola vaccine, in addition to reducing infection, can reduce mortality by half among people infected by the virus.
Ebola virus disease is, as explained by the World Health Organization (WHO), a serious infectious disease that spreads between humans through person-to-person transmission and its average fatality rate is around 50%. .
Currently, and according to this international organization, there are “vaccines that protect against some types of Ebola virus and have been used to control its spread in epidemic outbreaks, but other vaccines are being developed. One of them is this one: ‘Ervebo’ ; but now more benefits have been demonstrated.
An observational study carried out by the medical research and epidemiology center of Doctors Without Borders (MSF), in collaboration with the Institut National de Recherche Biomédicale (INRB) and the Ministry of Health of the Democratic Republic of the Congo (DRC), shows for the first time the effectiveness of ‘Ervebo’ against mortality.
That is, according to new results published in the journal ‘The Lancet’, they show that it reduces mortality in infected people by half. For this study, data collected during the tenth Ebola epidemic in the Democratic Republic of the Congo (DRC) has been analyzed, and reveals that of the 2,279 confirmed Ebola patients admitted to an Ebola treatment center between July 27, 2018 and on April 27, 2020, the risk of death was 56% among unvaccinated patients, but dropped to 25% for those who had received the vaccine.
This reduction in mortality occurred regardless of age or sex. This new study, funded by MSF, has focused on the ‘Ervebo’ vaccine, the only Ebola vaccine recommended for use during an epidemic.
Designed to be administered in a single dose, this vaccine is primarily recommended for ring vaccination of people at high risk of exposure during epidemics. This strategy consists of vaccinating contacts, contacts of these contacts, and healthcare or frontline workers.
The vaccine demonstrates its effectiveness against mortality
A Phase 3 clinical trial conducted in Guinea found that this vaccine strongly protects against Ebola virus disease.
However, some people, despite having been vaccinated for more than ten days, the period considered sufficient to develop immunity, were infected during the tenth Ebola epidemic in the DRC. This underscores the importance of describing not only the vaccine’s effectiveness against infection, but also its impact on mortality.
However, its impact on mortality during an epidemic had not yet been evaluated, although during the tenth Ebola epidemic in the DRC it appears that some people became infected with Ebola even though they had received the vaccine more than 10 days earlier.
Although the goal is to vaccinate people as early as possible during outbreaks, before exposure to Ebola virus disease, results from the Epicenter study show that the vaccine protects against the risk of death from Ebola even when people are vaccinated. They vaccinate late, that is, after having been exposed to the disease. Furthermore, in this study no antagonistic effect between vaccination and treatment against Ebola was observed.
“Vaccination after exposure to a person infected with Ebola virus disease, even when administered shortly before the onset of symptoms, confers significant protection against the risk of death. The reduction in the risk of death due to vaccination adds to the reduction due to specific Ebola treatment, regardless of the delay before treatment,” explains Rebecca Coulborn, Epicenter epidemiologist.
This study provides new evidence of the importance of Ebola vaccination during epidemics that occur regularly in sub-Saharan Africa. These are most frequently caused by the Zaire Ebolavirus species, which is associated with high mortality.
Since 2019, two vaccines, rVSV?G-ZEBOV-GP (Ervebo’) and Ad26.ZEBOV/MVA-BN-Filo, have obtained prequalification from the World Health Organization against this strain. “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 with confirmed Ebola virus disease to reduce the risk of illness and death,” says Etienne Gignoux, director of the Department of Epidemiology and Training at Epicenter.
2024-02-08 13:27:19
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