In December, the Food & Drug Administration announced its approval of the first Ebola vaccine for use in the United States. Made by Merck, Ervebo (pronounced er-VEE-boh) is for the prevention of disease caused by infection with Zaire ebolavirus in people 18 years of age and older.

Merck provides more information in a press release. The single-dose, live-attenuated vaccine, Ervebo does not protect against other species of Ebolavirus or Marburgvirus. The duration of protection conferred is unknown, as is the effectiveness of the vaccine when administered concurrently with blood or plasma transfusions, immune globulin (IG), and/or antiviral medications.

Patients with a history of anaphylaxis or other severe reaction to rice protein or other components of the vaccine should not receive Ervebo. The vaccine will likely become available in the third quarter of 2020.

“From research and development to support for manufacturing, the U.S. government played an integral role in advancing the development of Merck's vaccine,” said HHS Secretary Alex Azar. “The newly approved vaccine, as well as investigational therapeutics and other tools supported by the U.S. government, is playing a huge role in saving lives during the current Ebola outbreak in the Democratic Republic of the Congo.”

Healthcare workers are already using Ervebo as part of their “ring vaccination” strategy to control the current Ebola outbreak in the Democratic Republic of Congo (DRC). Ring vaccinations involve the vaccination and monitoring the ring of susceptible people around the infected individuals.

Health officials in the United States used ring vaccination to control smallpox until the last naturally occurring case in the nation in 1977. The FDA granted approval of Ervebo based on a ring vaccination in Guinea, which found that the rVSV-ZEBOV-GP Ebola vaccine was 100 percent effective in preventing Ebola cases more than 10 days after vaccination.

The European Medicines Agency had approved Ervebo in October for administration in the European Union (EU). While cases of Ebola are very rare in the U.S., affecting only 11 people in the nation during the 2014-16 epidemic, it has a death rate of up to 90% in humans.

Formerly known as Ebola haemorrhagic fever, Ebola virus disease spreads human-to-human transmission via direct contact through broken skin or mucous membranes. Its incubation period is two to 21 days, according to WHO.

Transmission is only possible after the infected individual develops symptoms, which can come on suddenly. Early symptoms include fever, headache, sore throat, fatigue, and muscle pain. Later, patients may develop vomiting, diarrhea, impaired liver and kidney function, and rash. Some patients may experience internal and external bleeding.

Laboratory findings include low platelet and white blood cell (WBC) counts, along with elevated liver enzymes. Diagnostic tests, such as virus isolation by cell culture, antibody-capture enzyme-linked immunosorbent assay (ELISA), reverse transcriptase polymerase chain reaction (RT-PCR) assay, antigen-capture detection tests, serum neutralization test, and electron microscopy can help confirm an Ebola diagnosis. These tests can help clinicians differentiate Ebola virus disease from malaria, meningitis, typhoid fever, and other infectious diseases.

DRC is struggling with the world’s second largest outbreak of Ebola on record. According to WHO records as of Dec. 26, 2019, there have been 2,227 lives lost, 3,366 confirmed or possible infections, and 1,098 survivors since official declaration of the outbreak on Aug. 1, 2018. More than 250,000 people have been vaccinated.

“Ebola virus disease is a rare but severe and often deadly disease that knows no borders. Vaccination is essential to help prevent outbreaks and to stop the Ebola virus from spreading when outbreaks do occur,” Peter Marks, MD, Ph.D., director of the FDA's Center for Biologics Evaluation and Research, said in the FDA press release.