The U.S. Approves First Vaccine for the Prevention of the Ebola Virus Disease that Killed Over 11,000 in Liberia, Sierra Leone, and Guinea

The U.S. Food and Drug Administration announced the approval of Ervebo, the first FDA-approved vaccine for the prevention of Ebola virus disease (EVD), caused by Zaire ebolavirus in individuals 18 years of age and older. Cases of EVD are very rare in the U.S., and those that have occurred have been the result of infections acquired by individuals in other countries who then traveled to the U.S., or health care workers who became ill after treating patients with EVD.

“While the risk of Ebola virus disease in the U.S. remains low, the U.S. government remains deeply committed to fighting devastating Ebola outbreaks in Africa, including the current outbreak in the Democratic Republic of the Congo,” said Anna Abram, FDA Deputy Commissioner for Policy, Legislation, and International Affairs. “Today’s approval is an important step in our continuing efforts to fight Ebola in close coordination with our partners across the U.S. Department of Health and Human Services, as well as our international partners, such as the World Health Organization. These efforts, including today’s landmark approval, reflect the FDA’s unwavering dedication to leveraging our expertise to facilitate the development and availability of safe and effective medical products to address urgent public health needs and fight infectious diseases, as part of our vital public health mission.”

EVD is contagious and is transmitted through direct contact with blood, body fluids and tissues of infected wild animals or people, as well as with surfaces and materials, such as bedding and clothing, contaminated with these fluids. The onset of symptoms of EVD can be sudden and can include fever, fatigue, muscle pain, headache, and sore throat. This is followed by vomiting, diarrhea, rash, impaired kidney and liver function and in some cases internal and external bleeding. EVD has an incubation period that ranges from 2 to 21 days. Individuals who provide care for people with EVD, including health care workers who do not use correct infection control precautions, are at the highest risk for infection.

An outbreak in three West African countries (Guinea, Liberia, and Sierra Leone) from 2014 to 2016 resulted in more than 28,000 cases of EVD and more than 11,000 deaths that were caused by Zaire ebolavirus.

The approval of Ervebo is supported by a study conducted in Guinea during the 2014-2016 outbreak in individuals 18 years of age and older. The study was a randomized cluster (ring) vaccination study in which 3,537 contacts and contacts of individuals with laboratory-confirmed EVD received either “immediate” or 21-day “delayed” vaccination with Ervebo.

This noteworthy design was intended to capture a social network of individuals and locations that might include dwellings or workplaces where a patient spent time while symptomatic or the households of individuals who had contact with the patient during that person’s illness or death.

In a comparison of cases of EVD among 2,108 individuals in the “immediate” vaccination arm and 1,429 individuals in the “delayed” vaccination arm, Ervebo was determined to be 100% effective in preventing Ebola cases with symptom onset greater than 10 days after vaccination. No cases of EVD with symptom onset greater than 10 days after vaccination were observed in the “immediate” cluster group, compared with 10 cases of EVD in the 21-day “delayed” cluster group.

In additional studies, antibody responses to Ervebo were assessed in 477 individuals in Liberia, approximately 500 individuals in Sierra Leone and approximately 900 individuals in Canada, Spain and the U.S. The antibody responses among those in the study conducted in Canada, Spain and the U.S. were similar to those among individuals in the studies conducted in Liberia and Sierra Leone.

The safety of Ervebo was assessed in approximately 15,000 individuals in Africa, Europe, and North America. The most commonly reported side effects were pain, swelling, and redness at the injection site, as well as headache, fever, joint and muscle aches, and fatigue.

Ervebo is administered as a single-dose injection and is alive, attenuated vaccine that has been genetically engineered to contain a protein from the Zaire ebolavirus.

The approval was granted to Merck & Co., Inc.