Merck’s Ebola Vaccine Demonstrates 84% Effectiveness in Real-World Setting During DRC Outbreak

Effectiveness:
Merck's Ebola vaccine, Ervebo, was found to be 84% effective in preventing Ebola virus disease in individuals vaccinated at least 10 days before exposure during the 2018-2020 outbreak in the Democratic Republic of the Congo (DRC).

Study Design:
The study used a test-negative design, analyzing data from 42 Ebola healthcare centers and assessing 26,438 people, of whom 1,273 tested positive for Ebola.

Consistency Across Groups:
The vaccine's effectiveness was consistent across sexes and age groups, with 80% effectiveness in females, 86% in males, 80% in children, and 83% in adults.

Real-World Impact:
This study provides the first real-world effectiveness estimates for the rVSV-ZEBOV Ebola vaccine during a large outbreak, confirming its high effectiveness in controlling Ebola outbreaks even in challenging environments.

Protection Against Death:
The vaccine also significantly reduced the risk of death among those who contracted Ebola, with a case-fatality risk of 25% in vaccinated individuals compared to 56% in unvaccinated individuals.

Viremia Levels:
Vaccinated patients had lower viremia levels compared to unvaccinated patients, supporting the vaccine's use as postexposure prophylaxis.