Research findings on three Ebola vaccine delivery strategies showed all protocols are safe and effective.
Cynthia Goldsmith
This colorized transmission electron micrograph (TEM) revealed some of the ultrastructural morphology displayed by an Ebola virus virion. See PHIL 1832 for a black-and-white version of this image.
Where is the Ebola virus found in nature? The exact origin, locations, and natural habitat (known as the “natural reservoir”) of the Ebola virus remain unknown. However, on the basis of available evidence and the nature of similar viruses, researchers believe that the virus is zoonotic (animal-borne) and is normally maintained in an animal host that is native to the African continent. A similar host is probably associated with Ebola-Reston which was isolated from infected cynomolgus monkeys that were imported to the United States and Italy from the Philippines. The virus is not known to be native to other continents, such as North America.
Two studies evaluating three Ebola vaccine delivery strategies in adults and children showed that all protocols were safe in both age groups, according to findings published today in the New England Journal of Medicine . Antibodies were produced in response to vaccine regimens starting 14 days after the first vaccination and continued to be detectable at varying levels – depending on the vaccine and regimen used – in both children and adults for one year. The study enrolled volunteers at sites in Guinea, Liberia, Sierra Leone and Mali to identify optimal vaccination strategies to limit Ebola virus disease outbreaks.
The studies were conducted within the international consortium Partnership for Research on Ebola Vaccination (PREVAC). The studies began enrollment in 2017 and were conducted concurrently. A total of 1,400 adults and 1,401 children aged 1 to 17 years received two injections of either placebo or Ebola vaccine in one of three regimens. The Ebola vaccines were Ad26.ZEBOV (supplied by Johnson & Johnson) followed eight weeks later by a booster dose of MVA-BN-Filo vaccine (supplied by the manufacturer Bavarian Nordic); two doses of rVSVΔG-ZEBOV-GP (manufactured by Merck Sharp & Dohme Corp) separated by eight weeks; or a dose of Merck vaccinefollowed eight weeks later by a placebo injection.
Antibody responses were observed within day 14 of the first injection of Ad26.ZEBOV or rVSVΔG-ZEBOV-GP vaccine. The researchers say this result is notable because Ebola virus disease vaccines are typically administered during an epidemic and thus information on how quickly a vaccine produces an antibody effect is potentially useful in efforts to protect populations at risk. Because no participants contracted Ebola virus disease during the study, the investigators were unable to assess protection from the disease.
- Randomized Trial of Vaccines for Zaire Ebola Virus Disease (nejm.org)
