According to results published today in the New England Journal of Medicine. Antibodies were produced in response to vaccine regimens from 14 days following the first vaccination and continued to be detectable at varying levels – depending on the vaccine and the regimen used – in children and adults for a year. The study recruited volunteers at sites in Guinea, Liberia, Sierra Leone and Mali to identify optimal vaccination strategies to reduce Ebola virus disease outbreaks.
The trials were conducted as part of the international consortium PREVAC (Partnership for Research on Ebola Vaccination). PREVAC’s partner organizations include the US National Institutes of Health (NIH), the French National Institute for Health and Medical Research, and the London School of Hygiene & Tropical Medicine. The National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH, sponsored the trial in Liberia and Mali. In Liberia, the study was carried out in collaboration with the Liberian Ministry of Health as part of the Liberia Ebola Virus Research Partnership Program. In Mali, it was conducted in collaboration with the University Center for Clinical Research and the Center for Vaccine Development-Mali.
The trials began recruiting in 2017, were conducted concurrently, and shared a placebo arm. A total of 1,400 adults and 1,401 children aged 1 to 17 years were randomized to receive two injections of placebo or Ebola vaccine in one of three treatment regimens. Ebola vaccine regimens were Ad26.ZEBOV (supplied by Johnson & Johnson) followed eight weeks later by a booster dose of MVA-BN-Filo vaccine (supplied by manufacturer Bavarian Nordic); two doses of rVSVΔG-ZEBOV-GP (manufactured by Merck Sharp & Dohme Corp) eight weeks apart; or a dose of the Merck vaccine followed eight weeks later by a placebo injection.
Antibody responses were observed on day 14 following the first injection of the Ad26.ZEBOV or rVSVAG-ZEBOV-GP vaccine. The researchers say the finding is noteworthy because Ebola virus disease vaccines are typically given during an outbreak, and information regarding how quickly a vaccine produces an antibody effect is therefore potentially useful in disease control efforts. protection of populations at risk. However, it is currently unknown what level of antibody response reliably correlates with vaccine-induced protection once morest Ebola virus infection or disease. As no participants contracted Ebola virus disease during the trial, investigators were unable to assess protection once morest the disease.
The researchers cite several strengths of the trials, including exceptional volunteer retention throughout the trial, achieved through continued community engagement and ongoing trust-building efforts.
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