Ebola Vaccine: Information for U.S. Healthcare Providers
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 18 of the 28 (64%) 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. Worldwide, EBOV outbreaks have infected more than 31,000 people and resulted in more than 12,000 deaths.
Importation of EVD to the United States from an epidemic region through an infected traveler, first responder, or healthcare worker is a recognized risk with 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 domestic healthcare workers who cared for the first travel-associated EVD case diagnosed in the U.S., a man who traveled from West Africa to Dallas, Texas, contracted EBOV. Both healthcare workers recovered.
The Ebola virus (Zaire ebolavirus) vaccine is a replication-competent, live, attenuated recombinant vesicular stomatitis virus (rVSV) vaccine. It is also known as V920, rVSVΔG-ZEBOV-GP or rVSV-ZEBOV; brand name ERVEBO® and manufactured by Merck. It is not possible to become infected with EBOV from the vaccine because the vaccine just 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.
The vaccine was approved by the U.S. Food and Drug Administration (FDA) on December 19, 2019 for the prevention of EVD caused by EBOV in people 18 years of age and older, based on the data from 12 clinical trials that included a total of 15,399 adults.
Clinical efficacy of the vaccine was supported by an open-label, randomized cluster (ring) vaccination study during the 2014-2016 outbreak in Guinea in which 3,537 people in close contact (within 2 meters) of diagnosed EVD cases (contacts) and their close contacts (contacts of contacts) received either immediate vaccination or delayed vaccination after 21 days or more. Clinical immunogenicity was assessed in three studies conducted in Liberia, Sierra Leone, Canada, Spain and the United States.
The rVSV-ZEBOV vaccine has been demonstrated to be safe and effective for preventing EVD infection in well-controlled clinical trials. The vaccine has been shown to elicit rapid immune response in 14 days after a single dose. Seroconversion in adults peaked between 28 and 35 days for most clinical trial subjects.
The rVSV-ZEBOV vaccine, however, does not provide protection against other species of Ebolavirus or Marburgvirus. Since evaluation of clinical efficacy and immunogenicity have not been conducted in the same study, it is not possible to define a correlate of protection at the individual level. It is not known how long rVSV-ZEBOV protects against EBOV, and whether it is effective when administered concurrently with antiviral medication, immune globulin, and/or blood or plasma transfusion.
On February 26, 2020, the Advisory Committee on Immunization Practices (ACIP) recommended pre-exposure vaccination with rVSV-ZEBOV vaccine for adults aged 18 years or older in the U.S. population who are at potential risk of exposure to EBOV. This recommendation includes adults who are
- Responding or may respond to an outbreak of EVD;
- Laboratorians or other staff working at biosafety-level 4 facilities in the United States; or
- Healthcare personnel* working at federally designated Ebola Treatment Centers in the United States.
The manufacturing of licensed vaccine doses by Merck is actively underway and the delivery of licensed vaccine supply to the Strategic National Stockpile is expected to begin before the end of 2020. However, the rVSV-ZEBOV vaccine is not planned for commercial marketing, and vaccine access within the U.S. will be facilitated through the U.S. government. The Centers for Disease Control and Prevention (CDC) is sponsoring an expanded access IND program to provide domestic access to existing doses of rVSV-ZEBOV that were manufactured prior to licensing (referred to as IND-labeled vaccine). CDC will make IND-labeled vaccine available for recommended use when licensed vaccine doses are unavailable or in limited supply.
CDC will provide IND-labeled vaccine when requested by licensed healthcare providers from institutions or sites with individuals who meet the eligibility criteria included in the 2020 ACIP recommendations pdf icon[PDF – 2.3 MB]. Under this expanded access IND program, the requesting healthcare providers will serve as site investigators and will assume the oversight responsibility for vaccine receipt, handling and use at their institutions or sites. They will also monitor and report any serious adverse events resulting from rVSV-ZEBOV administration. See the IND protocol #7298, Domestic Use of Ebola Zaire Vaccine (rVSV-ZEBOV; V920) for Pre-exposureProphylaxis (PrEP) Vaccination of Adults (≥ 18 years of age) at Potential Occupational Risk for Exposure to Zaire ebolavirus, for further details. pdf icon[PDF – 354 KB]
After reviewing the IND protocol to ensure the patient meets the eligibility criteria, licensed healthcare providers interested in getting the vaccine for their patient should send an email to firstname.lastname@example.org with subject line: request for Ebola vaccine. The CDC Ebola Vaccine IND Program will respond to provide the required forms for eligible requests. See Sections 5 and 7 of the IND protocol and the listed appendices for further details.
*Healthcare personnel (HCP) refers to all paid and unpaid persons serving in healthcare settings who have the potential for direct or indirect exposure to: 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 HCP include, but are not limited to, emergency medical service personnel, nurses, nursing assistants, physicians, 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).