First real-world analysis of Ebola vaccine reveals 84% effectiveness during Democratic Republic Congo outbreak – Merck Inc

When a deadly outbreak of the Ebola virus spread through the Democratic Republic of Congo in 2018, Merck’s then-unapproved vaccine (Ervebo) was quickly deployed to help address the crisis and provide protection to hundreds of thousands of recipients. Now, four years after that epidemic ended, a new analysis offers a clearer picture on the vaccine’s real-world effectiveness.

For the study, the researchers looked at data collected from Ebola treatment centers to gauge the real-world effectiveness of the vaccine during the 2018-20 outbreak in the DRC, according to an article published in The Lancet Infectious Diseases. The study, which is the first to evaluate the real-world effectiveness of “widespread use” of the vaccine, showed that Ervebo was 84% effective against the virus in people who were infected 10 or more days after vaccination.

The “test-negative analysis” determined the vaccine’s effectiveness by weighing the likelihood of Ebola-positive patients being vaccinated or unvaccinated during the period. The study framework has also been used to weigh vaccine effectiveness in other viral diseases such as influenza and COVID-19, the study authors noted, as the usual standard of running randomized controlled trials can present ethical concerns in the context of a virus epidemic.

See- “Effectiveness of rVSV-ZEBOV vaccination during the 2018–20 Ebola virus disease epidemic in the Democratic Republic of the Congo: a retrospective test-negative study”: Sophie Meakin, PhD , Justus Nsio, MD , Anton Camacho, PhD, Richard Kitenge, MD , Rebecca M Coulborn, MPH, Etienne Gignoux, MPH. et al. Open AccessPublished: August 20, 2024/DOI:https://doi.org/10.1016/S1473-3099(24)00419-5.