Ebola vaccines are administered to protect people from contracting Ebola virus disease (EVD), which is a viral hemorrhagic fever, caused by ebolaviruses.
Ebola virus, also known as Zaire ebolavirus, Sudan ebolavirus, and Bundibugyo ebolavirus, can cause severe hemorrhagic fever, leading to high case fatality rates (30–90%) in humans.
Ebola vaccines include replication-deficient adenovirus vectors, replication-competent vesicular stomatitis (VSV), human parainfluenza (HPIV-3) vectors, and virus-like nanoparticle preparations.
On December 19, 2019, the U.S. Food and Drug Administration announced the approval of Ervebo, for the prevention of EVD, caused by Zaire ebolavirus in individuals 18 years of age and older. The approval was granted to Merck & Co., Inc.
While cases of EVD are very rare in the USA, and those that have occurred have been the result of infections acquired by individuals in other countries. 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, says the FDA.
ERVEBO is a recombinant, replication-competent Ebola vaccine, consisting of a VSV, which has been genetically engineered to express a glycoprotein from the Zaire ebolavirus so as to provoke a neutralizing immune response to the Ebola virus. Between August 2018 and May 20, 2020, 303,905 people were vaccinated in the DRC.
Zabdeno and Mvabea Ebola vaccine therapy is a prime-boost vaccination approach for the prevention of infectious diseases. Between October 2019 and April 10, 2020, 20,339 people received the 1st dose of this vaccine and 9,560 of them received the 2nd booster vaccination.
rVSVN4CT1-EBOVGP1 is a Monovalent Ebola Zaire Vaccine candidate - in a preclinical study, was found safe and well-tolerated (no vaccine-associated arthritis, dermatitis, or dermal vaculitis was observed), and has a robust level of Ebola virus GP-specific immunogenicity.
The University of Tokyo announced ‘they will begin a clinical study on a vaccine candidate for the Ebola virus, a first in Japan.’ This Ebola vaccine was proven both safe and effective in tests involving monkeys. This experimental Ebola vaccine, developed in the lab of UW-Madison scientist Yoshihiro Kawaoka, was produced at Waisman Biomanufacturing.
Ebola Antiviral Therapeutics
There is currently no antiviral drug licensed by the U.S. FDA to treat EVD in people. Drugs that are being developed to treat EVD work by stopping the virus from making copies of itself, says the CDC.
During the 2018 eastern DRC outbreak, 4 investigational treatments were initially available to treat EVD patients. Two of those drugs called Regeneron (REGN-EB3) and mAb114, the overall survival rate was much higher. These 2 antiviral drugs currently remain in use in the DRC.
On April 17, 2020, the FDA accepted for Priority Review a new Biologics License Application for REGN-EB3, an investigational triple antibody cocktail treatment for EVD. Previously, REGN-EB3 received Orphan Drug and Breakthrough Therapy designation from the FDA.
On June 18, 2020, a study 'Recent successes in therapeutics for Ebola virus disease: no time for complacency' was published in The Lancet. 'Although the overall reduction to a residual 34–35% CFR with the most effective mAb-based therapeutics represents a remarkable step forward, the PALM results suggest substantial room to improve outcomes in the acute Ebola virus disease.'
On July 30, 2020, the Biomedical Advanced Research and Development Authority announced it entered an agreement to procure REGN-EB3 as part of the US government’s goal of building national preparedness for public health emergencies.
Ebola Vaccine History
On August 11, 2014, the WHO convened a meeting and concluded there was an “ethical imperative” to develop experimental Ebola vaccines.
West Africa is experiencing the largest, most severe, most complex outbreak of Ebola virus disease in history. Previous Ebola outbreaks have been contained by existing interventions, such as early detection and isolation, contact tracing and monitoring, and adherence to rigorous procedures of infection prevention and control. Effective treatments and vaccines would, however, dramatically strengthen the ability to counter the disease.
Using the groundwork laid by Yale scientists in the 1990s, the first-ever Ebola Zaire vaccine was recently approved by the European Commission.
"The Ervebo vaccine’s approval is the fruition of decades of research led by John Rose, Ph.D., a School of Medicine pathology professor emeritus, who developed a method to genetically engineer the harmless vesicular stomatitis virus, or VSV, to express proteins found on other viruses to build immunity without developing harmful symptoms. This was an 8-year endeavor in my lab at Yale,” Dr. Rose said in a Yale press release, published on December 3, 2019.
“We suspected that VSV, which is a type of RNA virus circulating among livestock that is harmless to humans, could be a very potent vaccine platform for numerous diseases, like influenza and HIV. The idea was to insert new genes from pathogens into VSV and use this genetically modified virus as a vaccine.”
When injected, the genetically modifiable virus developed by Dr. Rose’s group allows exposure to disease-causing proteins from a range of harmful viruses while circumventing illness. The body is then able to build immunity to the harmless “mimickers” of infection.
In the case of the Ervebo vaccine, immune cells respond to Ebola surface proteins built onto VSV, and immunological memory can develop without making people sick because the VSV system poses no harm.
According to Dr. Rose, the genetically engineered VSV platform was not intended for treating a specific disease, but rather to be modified for applications in numerous viral diseases. After developing the VSV platform, Dr. Rose and his collaborators provided this system to over 100 labs, including one in Germany working on an Ebola vaccine.
Note: Content Sources for this page include the World Health Organization, the US Centers for Disease Control and Prevention, clinicaltrials.gov, and the Precision Vaccinations news network. This information has been reviewed by Dr. Robert Carlson.