In 2014, an outbreak of Zaire ebolavirus in the West African countries of Guinea, Liberia and Sierra Leone resulted in more than 28,000 cases and 11,000 deaths. Ebola virus disease (EVD) outbreaks were documented since the 1970s. However, the widespread nature of the 2014 epidemic caused global fear. Many countries responded by imposing travel restrictions against West African nations. Fortunately, the U.S. Food and Drug Administration approved the first Ebola vaccine (Ervebo) in December 2019.

10 Facts About the Ervebo Ebola Vaccine

1. Trials began in 2018. The World Health Organization (WHO) and the Democratic Republic of the Congo (DRC) began to trial Ervebo in 2018 as an investigational vaccine under an expanded access program. The DRC experienced the world’s second-largest Ebola outbreak. The vaccine use aimed to prioritize people most at risk such as healthcare workers.
2. Roughly 290,000 people received vaccinations. In response to the Ebola outbreak in the DRC, more than 290,000 people have received the Ervebo vaccination under compassionate use protocols. Compassionate use allows for the limited allocation of an unlicensed vaccination due to a dangerous public crisis.
3. Ervebo is 100% effective. A study in Guinea during the 2014-2016 outbreak indicates that Ervebo was 100% effective for individuals 18 and older. In a comparison of cases, Ervebo was 100% effective in preventing cases of Ebola with symptom onset more than 10 days after inoculation. The comparison involved 2,108 participants in an “immediate” vaccination group and 1,429 participants in a “delayed” vaccination group.
4. Trials outside of West Africa. In addition to West Africa, trials of the Ebola vaccine occurred in Canada, Spain and the United States. Because Ebola is not endemic to Europe or North America, researchers wanted to measure the antibody response among individuals with no history of previous exposure. The antibody responses among participants in Canada, Spain and the U.S. were close to that of individuals in Liberia and Sierra Leone.
5. Ervebo is safe for all participants. Roughly 15,000 individuals in Africa, Europe and North America were part of vaccine trials. The trials determined that the vaccine is safe and effective for all individuals. Individuals reported only minor side effects.
6. Ervebo is a single-dose vaccine. Ervebo is a single-dose injection that does not require boosters. This allows for faster distribution and protection against EVD. The vaccine is a “live, attenuated vaccine that is genetically engineered to contain protein from the Zaire ebolavirus.”
7. The vaccine received priority review. Due to the importance of developing an Ebola vaccine as a public health measure, Ervebo received a priority review and a tropical disease priority review voucher by the FDA under a program supporting the development of new drugs for the prevention and treatment of tropical diseases. Ervebo also received a breakthrough therapy designation to assist with the development of the vaccine. The FDA worked closely with the company, Merck & Co., Inc., and completed the evaluation in less than six months.
8. The vaccine will be available to those most in need. Due to limited supplies of Ebola vaccines, Ervebo will be available as part of a ring vaccination strategy during future outbreaks. This strategy means that those most at risk will receive first priority. Vaccination efforts will start with people like healthcare workers and extend outward to other members of the community.
9. A global stockpile will be available in January 2021. Beginning in January 2021, a global stockpile of the vaccine will be available through the International Coordinating Group (ICG) on Vaccine Provision. The ICG also manages stockpiles of cholera, meningitis and yellow fever vaccines and will be responsible for decision-making on allocation.
10. Four African countries have licensed the vaccine. In February 2020, the Democratic Republic of the Congo (DRC), Burundi, Ghana and Zambia licensed the Ervebo vaccine. The license means the manufacturer can stockpile and widely distribute the vaccine within these countries. No further research or clinical trials are necessary with a license.

The Future

One cannot undo the damage of past outbreaks but the Ervebo Ebola vaccine may be a valuable tool for future Ebola prevention efforts. As the vaccine becomes widely available in future years, the World Health Organization hopes the population of West Africa will achieve herd immunity against the disease, eradicating the spread of EVD. The technology used in the development of the Ebola vaccine will also aid in the quick development of vaccines for future global outbreaks. As the world continues to struggle against COVID-19, the success of Ervebo provides a blueprint for the prevention and mitigation of future epidemics.

– Eliza Browning
Photo: Flickr