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Infectious disease

Deployment of Merck’s experimental Ebola vaccine well under way in the Democratic Republic of Congo

The first goal is to thwart the outbreak, but researchers also hope for new insights into combating the virus

by Lisa M. Jarvis
May 31, 2018 | A version of this story appeared in Volume 96, Issue 23


A photo of two health care workers in the Democratic Republic of Congo, one of whom is holding up a vial of Merck's Ebola vaccine.
Credit: WHO
Health care workers in Congo are selectively deploying Merck's experimental Ebola vaccine.

Vaccination against the deadly Ebola virus is well under way in the Democratic Republic of Congo. The goal is to extinguish the Ebola outbreak, which was first reported in early May, but researchers also hope to learn more about how to prevent and treat infections.

According to the World Health Organization, some 7,500 doses of Merck & Co.’s experimental Ebola vaccine V920 were deployed to Congo as part of a strategy to create an immunity buffer zone. As of May 27, 54 suspected cases of Ebola virus were reported; 25 of those infected—including two health care workers—have died.

More than 900 people are known to have been in contact with the confirmed Ebola cases. A priority has been containing spread of the virus in Mbandaka, a city with four confirmed cases. WHO says 420 at-risk people have been vaccinated there.

Those that have spent their careers studying Ebola are impressed with the speed of the response in Congo. “Mobilization of thousands of doses of vaccine early in the outbreak is tremendous,” says Erica Ollmann Saphire, a Scripps Research Institute professor and Ebola expert.

Although the main goal of the vaccination is to avoid a humanitarian crisis, the scientific community sees the rollout of V920 as a unique opportunity to learn more about combating the deadly virus.

“Human clinical data are essential for understanding the quality and duration of protection,” Ollmann Saphire says. “Animal models only tell you so much.”

Researchers also hope to learn whether V920 can protect different populations. Genetics differ between the people being vaccinated in Congo and those who were vaccinated amid the 2014–15 outbreak in Guinea and Liberia, Ollmann Saphire notes. Moreover, she says, people in Guinea were unlikely to have been previously exposed to Ebola, whereas Congo has experienced nine outbreaks of the virus.

Beyond vaccines, researchers might also learn more about the efficacy of experimental Ebola treatments. A variety of antivirals and antibody cocktails have been sent to Congo for possible use. They include remdesivir, an Ebola antiviral developed by Gilead Sciences during the previous outbreak. Gilead expected its shipment of 360 doses of remdesivir to arrive on May 30.


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