The rVSVΔG-ZEBOV-GP vaccine, the only one recommended against Ebola during epidemics, is able to halve mortality. This is what emerges from one observational study funded and conducted by Epicentre, the medical and epidemiological research center of Doctors Without Borders (in France), in collaboration with the National Institute of Biomedical Research (INRB) and the Ministry of Health of the Democratic Republic of Congo (DRC), and Published on Lancet Infectious Diseases.
I study
The impact of prophylaxis on mortality had not yet been evaluated during an epidemic, but it is an important data – underlined by the humanitarian organization – which adds to that on the protection conferred against the infection, instead evaluated in clinical studies.
The data used in this study were collected during the tenth Ebola epidemic in the DRC and concern over 2,200 people of both sexes and all ages: all those infected and hospitalized between July 2018 and April 2020 in one of the health facilities. The results show that mortality was 56% among the unvaccinated and 25% among those vaccinated with rVSVΔG-ZEBOV-GP. Furthermore, mortality also decreases when the vaccine is administered late, i.e. after exposure to the virus, and no antagonistic effect between vaccination and treatment for Ebola has been highlighted.
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“Vaccination after contact with a person affected by the Ebola virus, even if administered shortly before the onset of symptoms, still confers significant protection against death – he confirmed Rebecca Coulborn, epidemiologist at the MSF Epicentre center – The reduced risk of death thanks to vaccination adds to the risk reduction given by treatment against Ebola”. “In addition to the direct benefits,” she added Etienne Gignouxdirector of the epidemiology and training department at Epicentre – our results allow us to consider a possible combination of vaccination with the treatment of patients who have been directly in contact with confirmed cases of Ebola to reduce the risk of disease and death.”
What is Ebola
The disease of virus Ebola it is a very serious hemorrhagic fever, discovered in 1976 in the Democratic Republic of Congo. Six different strains of the virus are known: Zaire, Sudan, Ivory Coast, Bundibugyo and Reston. The first four are pathogenic for humans, and over the years have caused epidemics in several African countries, with mortality rates ranging from 25% to 90%. Zaire has been the most common for the last 10 years. The most recent epidemics have affected the DRC (the twelfth epidemic in 2021) and Uganda (2019 and 2022).
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The vaccine
To date, two vaccines have obtained prequalification from the World Health Organization against Ebola Zaire: rVSVΔG-ZEBOV-GP and Ad26.ZEBOV/MVA-BN-Filo (the WHO Medicines Prequalification Program guarantees that the medicines supplied by the contracting entities meet quality, safety and effectiveness standards). As MSF reports, the rVSVΔG-ZEBOV-GP vaccine (single dose) is recommended especially for ring vaccination, i.e. of people at high risk of exposure during epidemics, such as those who have been in contact with an infected individual and, in cascade, their contacts; healthcare workers and other frontline workers.
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MSf’s commitment against Ebola
In 2014, exactly 10 years ago, we witnessed the largest Ebola epidemic in history, which hit West Africa – in particular Liberia, Guinea and Sierra Leone: 28,646 people were infected and more than 11,300 died. Around a third of all patients were admitted to an MSF health centre, where 2,478 people were saved. MSF has been on the front line since the first days of the epidemic and at the peak of the spread it employed up to 4,000 national and 325 international workers, of which over 70 were Italian. Later, it launched projects dedicated to survivors and today continues to provide services to support healthcare systems devastated by the epidemic.