Ebola vaccines
17 June 2026 | Questions and answersNote: These Q&As use the virus taxonomy approved in April 2023 by the Executive Committee of the International Committee of Taxonomy on Viruses.
Ebola disease is caused by a group of viruses, known as orthoebolaviruses.
There are four species of orthoebolaviruses known to cause disease in humans:
- Ebola virus (EBOV) causing Ebola virus disease (EVD)
- Sudan virus (SUDV) causing Sudan virus disease (SVD)
- Taï Forest virus (causes Taï Forest virus disease)
- Bundibugyo virus (BDBV) causing Bundibugyo virus disease (BVD).
Currently, there is one licensed and WHO prequalified vaccine available only for EVD, caused by EBOV. EBOV has been responsible for the largest and most frequent outbreaks.
The Ervebo® vaccine is administered in one dose and recommended for use in EVD outbreak settings. The vaccine can be accessed through the International Coordinating Group (ICG) on Vaccine Provision global stockpile.
See the July 2024 WHO Strategic Advisory Group of Experts on Immunization (SAGE) recommendations for further information on EVD vaccination.
At present, there are no licensed vaccines for Sudan virus disease (SVD) or Bundibugyo virus disease (BVD).
At present, there are no licensed vaccines for Sudan virus disease (SVD) or Bundibugyo virus disease (BVD).
There is currently only one licensed vaccine for EVD and several candidate vaccines are at different stages of development for SVD and BVD.
- Learn more about candidate vaccines for Bundibugyo virus disease.
The Ervebo vaccine has been used under “expanded access” or what is also known as “compassionate use” for 16 000 people in Guinea in 2015 and for 345 000 people during the 2018-2020 outbreaks in the Democratic Republic of the Congo.
The Zabdeno and Mvabea vaccine was studied in a total of 3 367 adults, adolescents and children who participated in 5 clinical studies conducted in Europe, Africa and the United States of America. These studies demonstrated that the vaccine regimen is safe and could induce an immune response against the Ebola virus. Efficacy data in humans has been extrapolated from animal studies. The exact level of protection provided by the vaccine regimen is not yet fully known.
Ebola virus disease (EVD) vaccines are used during EVD outbreaks to help control transmission and protect people at risk of infection. They may also be used preventively to protect people at increased risk of exposure, such as health workers or frontline workers, before an outbreak occurs.
Ervebo® is the only licensed vaccine currently available. There is a global Ebola vaccine stockpile, managed by the International Coordinating Group (ICG) on vaccine provision. This stockpile allows WHO, countries and other partners to contain future EVD outbreaks by ensuring equitable and timely access to vaccines for populations most at risk during outbreaks.
When an outbreak of EVD is confirmed, countries can request vaccines through the ICG. The ICG will provide vaccines and operational cost support to eligible countries. Countries can also request vaccines to support preventive vaccination.
Those eligible for the vaccine during an EVD outbreak are:
- all people who have come into direct or indirect contact with a confirmed or a probable case; and
- frontline and health-care workers because they are at the highest risk of contracting the disease during an EVD outbreak response. Included are clinicians and nurses who treat patients, surveillance and contact tracing teams, laboratory staff, safe burial teams, community workers, traditional healers, drivers and other community key stakeholders who are likely to interact with confirmed or probable cases.
Vaccination is an important component of outbreak response. The goal is to protect individuals at highest risk of exposure, using a ring vaccination or targeted geographic strategy.
In vaccine studies conducted since 2015, most of the adverse effects were typically mild. Vaccinated individuals most commonly reported headache, fatigue, muscle pain and mild fever.
A ring vaccination strategy is one of the strategies used to contain disease outbreaks by vaccinating the close contacts and potential contacts of a confirmed or probable case, creating a "ring" of immunity around a confirmed or probable case to prevent transmission.
Someone is listed as a contact when he/she has been in touch with the body fluids (blood, vomit, saliva, urine, faeces, breast milk) or shared the linens, clothes, or dishes/eating utensils of a person with a confirmed or probable status of Ebola disease.
Potential contacts are neighbours, family members, or extended family members at the closest geographic boundary of all contacts, plus household members of all contacts.
A targeted geographic vaccination strategy involves vaccinating everyone in the neighbourhood or village, rather than vaccinating only the known contacts and potential contacts. This approach can be used when the cases are contained within a small geographic area or when contact tracing is difficult (e.g. difficult to access areas or when contact tracing is not feasible as in poor security settings).
The Ervebo® vaccine is indicated in individuals of 12 months of age and older during EVD outbreaks.
However, WHO recommends “off label” use in EVD outbreak settings including:
- children from birth
- pregnant and lactating women.
This means that each country should make the decision on whether or not to offer the vaccine to these categories of the population, based on their vulnerabilities and exposure to the risk of Ebola infection.
People who survive EVD usually develop some natural protection against the disease. This protection is believed to last for several years, although it may slowly decrease over time.
EVD survivors are encouraged to apply all the protective measures against EVD, including vaccination.
Vaccination against EVD provides individual and collective immunity that reduces the harmful effects of the disease, including severe illness and death.
Unvaccinated persons have a high risk of dying in case of infection and increase the risk of the spread of the virus within the community.
It is important to ensure that all people at immediate risk of Ebola virus infection are immunized to protect themselves and others.
Most common side effects associated with the EVD vaccine are mild and occur within 24-48 hours of being vaccinated.
After receiving the EVD vaccine, people can experience:
- injection site pain
- fever
- headache.
Symptoms will generally disappear within 24 hours of onset.
According to evidence, it takes between 10 and 14 days to develop a complete immune response. This means that a person can still get infected before the vaccine provides full protection.
Vaccines are not 100% effective. A person who has been vaccinated against EVD can still become infected, although vaccination helps reduce the risk of disease and may reduce the risk of severe illness and death. In addition, not everyone develops the same level of protection after vaccination.
Because the Ebola virus disease vaccine is often given to people at highest risk of exposure during an outbreak, some people may already have been infected with the virus before they received the vaccine, even if they do not yet have symptoms.
If a person was infected before vaccination, they may still develop Ebola virus disease after receiving the vaccine. Anyone who develops symptoms of illness after vaccination should immediately seek medical care and contact the vaccination team.
People who have received the vaccine should continue to follow public health advice and take steps to protect themselves from infection.
They should avoid touching a patient’s body (dead or alive), or their body fluids, including blood, vomit, tears, saliva, urine or faeces, as well as patients’ personal items such as bedding and clothes.
No, it is not possible to be infected with Ebola as a result of vaccination. The vaccine contains only a small part of Ebola virus that helps the body's immune system recognize and respond to the virus in the future. It does not contain the complete Ebola virus needed to cause EVD.
If someone develops EVD after vaccination, it is most likely because they were infected before they received the vaccine or before the vaccine had enough time to provide protection.
Antibodies to the virus have been detected up to five years after vaccination. However, it is not known whether this level of antibodies is enough to protect against infection. Therefore, revaccination is recommended for anyone at high risk during an outbreak if they have not received an Ebola vaccine in the last six months.
Research is ongoing to learn more about booster doses.
There is no data available regarding receipt of a subsequent dose of an Ebola vaccine that is different to the one originally received.
Vaccination is just one component of a strategy to control an Ebola outbreak. Other important components include:
- early detection of new Ebola infections through active surveillance;
- functional laboratory services to confirm Ebola infections;
- separating (isolating) patients to prevent further spread at home or in the community and to provide safe and supportive care;
- safely and respectfully burying the dead to reduce further spread of Ebola virus through contact with deceased patients; and
- systematically engaging communities from the start in the Ebola response.