On Aug. 21, 2024, French and Democratic Republic of the Congo (DRC) researchers announced that a real-world study found that Merck’s rVSV-ZEBOV Ebola vaccine was 84% effective against infection during the country’s 2018-2020 Ebola outbreak.

French and DRC researchers used a test-negative design, analyzing clinical data from 42 Ebola healthcare centers (12 treatment, 9 transit, and 21 decentralized centers). They assessed data on 26,438 people, 1,273 of whom tested positive for Ebola. The study results were published in The Lancet Infectious Diseases.