Ebola Vaccine: Information about ERVEBO®

Why an Ebola vaccine is important

A safe and effective vaccine is an important tool to protect frontline workers and prevent the introduction and spread of Ebola in the United States.

Ebola virus is a zoonotic pathogen that causes severe hemorrhagic fever in humans, known as Ebola virus disease (EVD). There are four species of Ebola virus that have been known to cause disease in humans. Of these, species Zaire ebolavirus (EBOV) is the most lethal, with case fatality rates of 70–90% if left untreated.  EBOV is responsible for the majority of recorded EVD outbreaks. This includes the two largest EVD outbreaks in history, the 2014–2016 West Africa outbreak and the 2018 outbreak in eastern Democratic Republic of the Congo, where over 32,000 people were infected, and more than 13,600 deaths were reported.

Importation of EVD to the United States from an epidemic region through an infected traveler is a recognized risk with the potential for spread to other people. During the 2014–2016 Ebola outbreak in West Africa, 11 people were treated for EVD in the U.S., and two of them died. Nine of these cases were imported into the U.S. Two were domestic healthcare workers who were infected while caring for the first travel-associated EVD case diagnosed in the U.S. Both healthcare workers recovered.

The Ebola virus vaccine

ERVEBO® (Ebola Zaire Vaccine, Live also known as V920, rVSVΔG-ZEBOV-GP or rVSV-ZEBOV) is approved by the U.S. Food and Drug Administration (FDA) for the prevention of disease caused by Zaire ebolavirus in individuals 18 years of age and older as a single dose administration. ERVEBO is a replication-competent, live, attenuated recombinant vesicular stomatitis virus (rVSV) vaccine manufactured by Merck. It is not possible to become infected with EBOV from the vaccine because the vaccine only contains a gene from the Ebola virus, not the whole virus. Specifically, it contains a gene for the EBOV glycoprotein that replaces the gene for the native VSV glycoprotein. ERVEBO does not provide protection against other species of Ebolavirus or Marburgvirus.

Antibody measurements are often used as a surrogate test to predict when protection by a vaccine can be expected. Clinical trials have shown that the vaccine elicits rapid antibody response in 14 days after a single dose. Clinical efficacy of the vaccine was supported by a randomized cluster (ring) vaccination study during the 2014–2016 outbreak in Guinea. In this study, 3,775 people in close contact with diagnosed EVD cases (contacts) and their close contacts (contacts of contacts) received immediate vaccination. No one who was vaccinated immediately developed EVD 10 or more days after vaccination.

The correlate of protection, or the specific immune response to the ERVEBO vaccine that closely relates to protection against infection with EBOV, is unknown and still being studied. It is also not known whether it is effective when administered concurrently with antiviral medication, immune globulin, and/or blood or plasma transfusion. The duration of protection conferred by an initial dose of ERVEBO is also unknown. A booster dose for people who have been previously vaccinated may extend the duration of protection for ERVEBO. Scientists continue to monitor people who have received the vaccine to learn more.

Ebola vaccine eligibility

ERVEBO is not currently commercially marketed in the U.S. but is currently stockpiled in the Strategic National Stockpile and is made available through CDC for pre-exposure vaccination of individuals who fall into one of the three occupational categories:

  1. Ebola virus disease (EVD) responders to an Ebola virus (species Zaire ebolavirus) outbreak.
  2. Laboratorians and support staff working at biosafety level 4 (BSL-4) or Laboratory Response Network facilities in the United States that handle specimens that contain or might contain replication-competent Ebola virus (species Zaire ebolavirus).
  3. Healthcare personnel (HCP)* at federally designated Ebola Treatment Centers or state-designated Special Pathogens Treatment Centers** involved in the care and transport of patients infected or suspected to be infected with Ebola virus (species Zaire ebolavirus).

Disclaimer: The mention of any product names or non-United States Government entities on CDC Ebola websites is not meant to serve as an official endorsement of any such product or entity by the CDC, the Department of Health and Human Service, or the United States Government.

Booster dose eligibility

Given booster dose vaccination is not covered under ERVEBO’s FDA-approved indication, the Centers for Disease Control and Prevention (CDC) is sponsoring an expanded access Investigational New Drug (IND) program pdf icon[PDF – 610 KB] to allow booster dose administration for pre-exposure prophylaxis in adults (≥ 18 years of age) who were previously vaccinated (e.g., ≥ 6 months since prior vaccination) and who have potential risk of occupational exposure to Zaire ebolavirus. Final eligibility decisions of booster doses will be assessed on an individual basis.

Resources
Footnotes

*Healthcare personnel (HCP) refers to all paid and unpaid persons serving in healthcare settings who have the potential for direct or indirect exposure to Ebola patients or infectious materials, including body substances (e.g., blood, tissue, and specific body fluids); contaminated medical supplies, devices, and equipment; contaminated environmental surfaces; or contaminated air. These healthcare personnel include, but are not limited to, emergency medical service personnel, nurses, nursing assistants, physicians, physician assistants, technicians, clinical laboratory personnel, autopsy personnel, therapists, phlebotomists, pharmacists, students and trainees, contractual staff not employed by the healthcare facility, and persons not directly involved in patient care, but who could be exposed to infectious agents that can be transmitted in the healthcare setting (e.g., clerical, dietary, environmental services, laundry, security, engineering and facilities management, administrative, billing, and volunteer personnel).

Adapted from https://www.cdc.gov/infectioncontrol/guidelines/healthcare-personnel/index.html

**Healthcare facilities that intend to receive and are able to provide care for a suspect or confirmed patient with Ebola virus disease (EVD) for the duration of their illness, as assessed by their state health department. In addition to EVD, these facilities may also be designated by the states to treat other high consequence pathogens.