Ervebo (rVSV-ZEBOV)
Ebola Zaire Vaccine, Live — Recombinant Vesicular Stomatitis Virus Vaccine
Ervebo is the first approved vaccine for the prevention of Ebola virus disease caused by the Zaire ebolavirus. Given as a single intramuscular injection, it demonstrated 100% efficacy in a landmark ring vaccination trial during the 2014–2016 West Africa Ebola outbreak. Ervebo is approved for individuals aged 1 year and older and is recommended by the WHO for use during Ebola outbreaks.
Quick Facts
Key Takeaways
- Ervebo is a single-dose live vaccine that protects against Ebola virus disease caused by the Zaire ebolavirus species only.
- The vaccine demonstrated 100% efficacy from day 10 post-vaccination in the pivotal ring vaccination trial in Guinea.
- It cannot cause Ebola disease, but the vaccine virus may be shed in body fluids for up to 6 weeks after vaccination.
- Common side effects include headache, fever, muscle pain, joint pain, and injection site reactions—most resolve within days.
- Ervebo requires ultra-cold storage at −80°C to −60°C, though thawed vaccine can be kept at 2–8°C for up to 14 days.
What Is Ervebo and What Is It Used For?
Ervebo (rVSVΔG-ZEBOV-GP) is a groundbreaking vaccine that provides protection against Ebola virus disease (EVD) caused specifically by the Zaire ebolavirus species. It was first approved by the European Medicines Agency (EMA) in November 2019 and subsequently by the U.S. Food and Drug Administration (FDA) in December 2019, making it the first Ebola vaccine to receive regulatory approval anywhere in the world. The World Health Organization (WHO) prequalified the vaccine in November 2019, facilitating its rapid deployment during outbreaks in endemic regions.
The vaccine works by using a modified version of vesicular stomatitis virus (VSV), an animal virus that does not cause significant disease in humans. Scientists engineered this virus by replacing its surface glycoprotein (G protein) with the glycoprotein (GP) from the Zaire ebolavirus. When the vaccine is injected, the immune system recognizes the Ebola surface protein and generates both antibody and cellular immune responses against it, providing protection should the individual later encounter the actual Ebola virus.
It is critically important to understand that Ervebo does not contain the whole Ebola virus and therefore cannot cause Ebola disease. The vaccine contains only a single protein from the Ebola virus surface, carried on a harmless modified virus. Additionally, Ervebo protects only against the Zaire species of Ebola—it does not protect against other ebolavirus species such as Sudan, Bundibugyo, or Taï Forest ebolaviruses.
What Is Ebola Virus Disease?
Ebola virus disease (EVD) is a severe, often fatal illness in humans caused by viruses of the Ebolavirus genus. The Zaire ebolavirus, which Ervebo protects against, is the most lethal species with case fatality rates historically ranging from 25% to 90%, depending on the outbreak and the level of supportive care available. The 2014–2016 West Africa Ebola epidemic was the largest in history, with more than 28,600 cases and over 11,300 deaths across Guinea, Sierra Leone, and Liberia.
Ebola is transmitted through direct contact with blood and body fluids (including urine, saliva, sweat, vomit, breast milk, semen, and vaginal fluids) of infected individuals, whether alive or deceased. Transmission can also occur through contact with contaminated surfaces and materials such as bedding, clothing, and medical equipment. The virus is not transmitted through the air, water, or food. Symptoms typically appear 2 to 21 days after exposure and include sudden onset of fever, intense weakness, muscle pain, headache, sore throat, vomiting, diarrhea, rash, impaired kidney and liver function, and in some cases, internal and external bleeding.
Healthcare workers treating Ebola patients and individuals involved in burial ceremonies are at particularly high risk of exposure. Proper infection prevention and control measures, including personal protective equipment (PPE), remain essential even after vaccination. Ervebo is typically recommended during outbreak responses and for individuals with occupational risk of Ebola exposure, such as laboratory workers handling Ebola specimens and healthcare workers in endemic regions.
What Should You Know Before Receiving Ervebo?
Contraindications
Ervebo should not be administered to individuals who have had a confirmed allergic reaction (hypersensitivity) to the active substance, to rice protein, or to any of the other ingredients in the vaccine. Because Ervebo is produced using Vero cells and contains a trace amount of rice protein from the production process, individuals with known rice allergy should inform their healthcare provider before vaccination. If you are unsure whether any of these contraindications apply to you, consult your doctor, pharmacist, or nurse before receiving the vaccine.
Warnings and Precautions
Not all individuals who receive Ervebo will develop protective immunity, and the exact duration of protection conferred by the vaccine remains under investigation. Even after vaccination, it is essential to continue following all recommended infection prevention and control measures, including proper hand hygiene, use of personal protective equipment where appropriate, and avoidance of contact with blood and body fluids of potentially infected individuals.
Thorough handwashing is the single most effective measure for preventing the spread of dangerous pathogens, including Ebola virus. Use soap and water when hands are visibly soiled with dirt, blood, or other body fluids. Use alcohol-based hand sanitizer when hands are not visibly dirty. Do not use alcohol-based hand sanitizer when hands are contaminated with blood or body fluids.
Immunocompromised individuals: If your immune system is weakened (immunocompromised), you may not be able to receive Ervebo, or the vaccine may not work as effectively. Your immune system may be compromised if you have HIV infection or AIDS, are taking immunosuppressive medications or corticosteroids, have cancer or a blood disorder that weakens immunity, or if a family member has a congenital immune deficiency. Discuss your situation with your healthcare provider before vaccination.
Vaccine virus shedding: Because Ervebo is a live vaccine, the vaccine virus may be present in body fluids (including blood, urine, saliva, and semen) for up to 6 weeks after vaccination. During this period, take precautions to prevent transmitting the vaccine virus to vulnerable individuals, including infants under 1 year of age, pregnant or breastfeeding women, and immunocompromised persons. If you develop a skin rash with open lesions after vaccination, cover the affected area until healed and dispose of bandages in a sealed container.
Care of vaccinated children: For at least 6 weeks after a child receives Ervebo, wash your hands thoroughly after contact with the child's blood or body fluids. Soiled diapers should be washed with appropriate detergent or, if disposable, sealed in double plastic bags before disposal with household waste.
Blood donation and livestock contact: Do not donate blood for at least 6 weeks after vaccination. Also ensure that your blood and body fluids do not come into close contact with farm animals for at least 6 weeks, as there is a risk of transmitting the vaccine virus to livestock.
You may test positive for Ebola virus after receiving Ervebo. This does not mean you have Ebola. Inform your healthcare provider that you have been vaccinated so that they can use an appropriate alternative test to rule out actual Ebola infection.
Fever and illness: If you have a fever, vaccination may need to be postponed until the fever resolves. A mild infection such as a common cold should not be a problem, but consult your healthcare provider before receiving the vaccine.
Bleeding disorders: Tell your healthcare provider if you have a bleeding disorder or bruise easily. Ervebo may cause bleeding or bruising at the injection site.
Pregnancy and Breastfeeding
If you are pregnant, breastfeeding, think you may be pregnant, or are planning to become pregnant, consult your healthcare provider before receiving Ervebo. The risks and benefits of vaccination should be carefully weighed, particularly during active Ebola outbreaks where the risk of disease may outweigh potential vaccine risks. It is not known whether Ervebo can harm the mother or fetus, or whether the vaccine virus passes into breast milk.
Women of childbearing potential should use effective contraception for at least 2 months after vaccination. If you will be in close contact with, or in the same household as, someone who may be pregnant or is breastfeeding during the 6 weeks following vaccination, inform your healthcare provider, as you could potentially transmit the vaccine virus through body fluids.
Children Under 1 Year
Ervebo is not recommended for children younger than 1 year of age due to insufficient data on safety and efficacy in this age group. If your child is under 1 year of age, consult your healthcare provider.
Other Medicines and Vaccines
Tell your healthcare provider about all medications, supplements, or vaccines you are currently taking, have recently taken, or plan to take. No formal drug interaction studies have been conducted with Ervebo, and co-administration with other vaccines is not recommended due to lack of data. If you are scheduled to receive blood or blood products, do not receive Ervebo at the same time. The vaccine may be less effective if administered within 3 months after receiving blood or blood products, or within 1 month before receiving them.
Sodium Content
Ervebo contains less than 1 mmol (23 mg) of sodium per dose, meaning it is essentially sodium-free.
How Does Ervebo Interact with Other Drugs?
Because Ervebo is a live, attenuated vaccine, its interaction profile differs from conventional pharmaceutical drugs. The primary concern is that agents that suppress the immune system may reduce the vaccine's ability to generate a protective immune response. Similarly, blood products contain antibodies that could neutralize the vaccine virus before it has time to stimulate adequate immunity.
| Interacting Agent | Type | Effect | Recommendation |
|---|---|---|---|
| Immunosuppressive drugs (e.g., cyclosporine, tacrolimus) | Major | May reduce vaccine immunogenicity and increase risk of vaccine virus replication | Assess risk-benefit; may need to delay vaccination or adjust immunosuppression |
| Systemic corticosteroids (high dose) | Major | May impair immune response to vaccine | Discuss timing with healthcare provider; low-dose topical steroids are generally acceptable |
| Blood and blood products | Major | Antibodies in blood products may neutralize vaccine virus | Do not give simultaneously; avoid 3 months before and 1 month after vaccination |
| Other live vaccines | Moderate | No data on co-administration; potential for immune interference | Co-administration not recommended due to lack of data |
| Antiretroviral therapy (for HIV) | Moderate | HIV-positive individuals on stable ART may have reduced immune response | Can be given if CD4 count is adequate; monitor immune response |
| Chemotherapy agents | Major | Severe immunosuppression reduces vaccine effectiveness and increases safety risk | Contraindicated during active chemotherapy; discuss timing with oncologist |
It is important to note that the absence of formal interaction studies means these recommendations are based on general principles of live vaccine immunology and expert clinical guidance. During active Ebola outbreaks, the risk-benefit assessment may favor vaccination even in the presence of relative contraindications, given the extremely high mortality rate of Ebola virus disease.
What Is the Correct Dosage of Ervebo?
Ervebo is administered exclusively by healthcare professionals trained in vaccination techniques. The vaccine is supplied as a solution for injection in single-dose vials. Each vial contains 1 mL of vaccine solution, delivering at least 72 million plaque-forming units (PFU) of the recombinant vesicular stomatitis virus carrying the Zaire ebolavirus glycoprotein.
Adults (18 Years and Older)
Standard Adult Dose
Dose: 1 mL (single injection)
Route: Intramuscular (IM) injection
Site: Deltoid muscle of the non-dominant arm (preferred) or upper anterolateral thigh
Schedule: Single dose; no booster currently recommended
The injection site should be covered with an adhesive bandage or gauze dressing to provide a physical barrier against direct contact with fluid from any vesicle that may develop. The dressing can be removed when there is no visible fluid leakage.
Children and Adolescents (1 to 17 Years)
Pediatric Dose
Dose: 1 mL (single injection) — same as adult dose
Route: Intramuscular (IM) injection
Site: Deltoid muscle or anterolateral thigh (depending on age and muscle mass)
Schedule: Single dose
The vaccine has been studied in children and adolescents aged 6 to 17 years. The same 1 mL dose is used regardless of age or body weight within the approved age range. Safety and immunogenicity data in children aged 1 to 5 years are more limited but support the same dosing regimen.
Elderly
No dose adjustment is required for elderly individuals. However, as immune function naturally declines with age, elderly persons may mount a reduced immune response to the vaccine. The decision to vaccinate elderly individuals should be based on the risk of Ebola exposure and overall health status. Clinical trial data in individuals over 65 years are limited.
Missed Dose
Ervebo is a single-dose vaccine with no scheduled booster, so a missed dose scenario in the traditional sense does not apply. If an individual was scheduled to receive Ervebo but did not, the vaccine can be administered at the next available opportunity without needing to restart any series. There is no upper time limit for rescheduling the vaccination.
Overdose
Because Ervebo is administered as a single pre-filled dose by a healthcare professional, overdose is extremely unlikely. In the event that more than one dose is inadvertently administered, the individual should be monitored for adverse effects, and the event should be reported to the relevant pharmacovigilance authority. No specific antidote exists, and management would be supportive and symptomatic.
Ervebo must be administered intramuscularly only. It must not be injected intravascularly. There are no data supporting subcutaneous or intradermal administration. The vaccine must not be mixed in the same syringe with any other vaccine or medicinal product. Draw up the entire contents of the vial using a sterile needle and syringe.
What Are the Side Effects of Ervebo?
Like all vaccines, Ervebo can cause side effects, although not everybody gets them. The side effects observed in clinical trials are generally signs that the immune system is responding to the vaccine and building protection. Most side effects are mild to moderate in intensity and resolve without medical intervention within a few days of vaccination.
Rarely, serious allergic reactions (anaphylaxis) may occur. Seek emergency medical care immediately if you experience: wheezing or difficulty breathing, swelling of the face, lips, tongue or other parts of the body, widespread itching, redness, flushing, or itchy lumps on the skin.
Side Effects in Adults (18 Years and Older)
Very Common
May affect more than 1 in 10 people
- Headache
- Abdominal pain
- Decreased appetite
- Joint pain (arthralgia)
- Muscle pain (myalgia)
- Fever
- Fatigue or drowsiness
- Chills
- Injection site pain, swelling, or redness
Common
May affect up to 1 in 10 people
- Dizziness
- Nausea
- Mouth sores (oral ulcers)
- Skin rash
- Joint swelling or joint stiffness
- Injection site itching
- Excessive sweating
- Decreased white blood cell count (transient, not associated with illness)
Most side effects resolve within a few days. However, joint pain and joint swelling may sometimes persist for weeks or months. In some individuals, joint symptoms may recur after initially resolving. This is thought to be related to the immune response generated by the vaccine and is generally self-limiting.
Side Effects in Children and Adolescents (1 to 17 Years)
Very Common
May affect more than 1 in 10 children
- Headache
- Abdominal pain
- Decreased appetite
- Muscle pain
- Fever
- Fatigue or drowsiness
- Chills
- Injection site pain
Common
May affect up to 1 in 10 children
- Dizziness
- Nausea
- Mouth sores
- Joint pain
- Crying (in younger children)
- Injection site swelling or itching
- Excessive sweating
Rare
May affect up to 1 in 100 children
- Injection site redness
The side effect profile in children and adolescents aged 6 to 17 years is generally similar to that observed in adults. The vaccine has been studied in a smaller number of children and adolescents compared to adults, so rarer side effects may not yet have been identified in this age group. Parents and caregivers should monitor vaccinated children and report any concerning symptoms to a healthcare provider.
It is important to report suspected side effects after vaccination. This enables ongoing monitoring of the vaccine's benefit-risk balance. Healthcare professionals and patients are encouraged to report adverse events to their national pharmacovigilance authority (e.g., the EMA's EudraVigilance system, the FDA's VAERS system, or the WHO's VigiBase).
How Should Ervebo Be Stored?
Ervebo has strict cold chain requirements that are essential for maintaining the vaccine's potency and safety. The vaccine must be stored and transported in a deeply frozen state at −80°C to −60°C. These ultra-cold storage requirements can present logistical challenges, particularly in resource-limited settings where Ebola outbreaks most commonly occur. Specialized cold chain equipment, such as ultra-low temperature freezers and insulated shipping containers with dry ice, is required for proper storage and distribution.
When ready for use, the vaccine should be removed from the freezer and thawed at room temperature for no more than 4 hours until no ice is visible. Do not thaw in a refrigerator, as this does not guarantee complete thawing within 4 hours. Once thawed, gently invert the vial several times before drawing the vaccine into a syringe—do not shake vigorously.
After thawing, Ervebo should ideally be used immediately. However, stability data show that the thawed vaccine can be stored at 2°C to 8°C for up to 14 days before use. If not used within 14 days after thawing, the vaccine must be discarded. When removing the vaccine from the freezer, label the product with both the date it was removed from the freezer and a new discard date (replacing the printed expiration date). The vaccine cannot be refrozen once thawed.
Keep the vial in its outer carton at all times to protect the vaccine from light. Ervebo is a colorless to slightly brownish-yellow liquid. Do not use the vaccine if you notice visible particles in the solution. Unused vaccine and waste should be disposed of in accordance with applicable guidelines for genetically modified organisms or biohazardous waste.
Keep this vaccine out of the sight and reach of children. Do not use after the expiry date stated on the vial label and outer carton (after EXP). The expiry date refers to the last day of the indicated month.
What Does Ervebo Contain?
The active substance in Ervebo is a genetically engineered virus: a recombinant vesicular stomatitis virus (rVSV) of the Indiana strain, in which the VSV envelope glycoprotein (G) has been replaced with the surface glycoprotein (GP) of the Zaire ebolavirus (ZEBOV), Kikwit 1995 strain. Each 1 mL dose contains at least 72 million plaque-forming units (PFU) of this recombinant virus. The vaccine virus is produced in Vero cells (a standard cell line used in vaccine manufacturing).
Because this product contains genetically modified organisms (GMOs), specific regulations regarding its handling, transport, and disposal may apply in different jurisdictions. The vaccine also contains a trace amount of rice protein, which is relevant for individuals with rice allergy.
Excipients (Inactive Ingredients)
- Recombinant human serum albumin — acts as a stabilizer to maintain vaccine potency during storage
- Trometamol buffer — maintains the appropriate pH of the solution
- Water for injections — the solvent
- Hydrochloric acid and sodium hydroxide — used for pH adjustment
Ervebo is supplied as a solution for injection in a single-dose vial (Type I glass) with a chlorobutyl rubber stopper and a plastic snap-off cap with aluminium seal. The vaccine is available in packs of 10 vials. The solution is colorless to slightly brownish-yellow in appearance.
What Precautions Should You Follow in Ebola-Affected Areas?
Vaccination with Ervebo is an important tool in the fight against Ebola, but it does not replace the comprehensive infection prevention and control (IPC) measures that are essential during an outbreak. All vaccinated individuals, including healthcare workers, must continue to follow standard precautions as recommended by the WHO and national health authorities.
In Ebola-affected areas, it is critically important to avoid the following:
- Contact with blood and body fluids (including urine, feces, saliva, sweat, vomit, breast milk, semen, and vaginal fluids) of infected or potentially infected individuals
- Contact with objects that may have been contaminated with an infected person's blood or body fluids (such as clothing, bedding, needles, and medical equipment)
- Unsafe burial practices that require handling the body of someone who died of Ebola
- Contact with bats, primates, or with blood, fluids, and raw meat prepared from these animals (bushmeat) or meat from an unknown source
- Contact with semen from a man who has had Ebola — practice safe sex until the virus is confirmed to have cleared from the semen
Healthcare workers caring for patients with suspected or confirmed Ebola must apply additional infection control measures beyond standard precautions. These include wearing full PPE (face shields or medical masks with goggles, clean non-sterile long-sleeved gowns, and gloves) when within 1 meter of Ebola patients. Laboratory specimens from suspected cases must be handled by trained personnel and processed in appropriately equipped facilities.
Frequently Asked Questions About Ervebo
In the pivotal ring vaccination trial conducted in Guinea, Ervebo provided protection starting from approximately 10 days after vaccination. No cases of Ebola were recorded among vaccinated individuals from day 10 onward in the immediate vaccination group. However, the exact onset of protection may vary between individuals, and maximum immunity may take up to 28 days to develop. During this window period, individuals should continue to follow all Ebola prevention measures.
No. Ervebo protects only against Ebola virus disease caused by the Zaire ebolavirus species. There are five known ebolavirus species: Zaire, Sudan, Bundibugyo, Tai Forest, and Reston. The Zaire species has caused the majority of Ebola outbreaks and the highest fatality rates. For the Sudan ebolavirus, a separate vaccine candidate (developed by the Sabin Vaccine Institute) has shown promise in clinical trials. There is currently no approved vaccine for the other ebolavirus species.
While Ervebo provides significant protection against Zaire ebolavirus, vaccination alone is not sufficient for safe travel to Ebola-affected areas. You should wait at least 10 days (preferably 28 days) after vaccination before potential exposure. Additionally, you must follow all recommended infection prevention measures, including hand hygiene, avoiding contact with blood and body fluids, and using appropriate PPE if working in healthcare settings. Consult your travel health provider for personalized advice.
The exact duration of protection provided by Ervebo is not yet fully established. Follow-up studies from the ring vaccination trial have shown that antibody levels remain elevated for at least 2 years after vaccination. Long-term surveillance studies are ongoing to determine whether a booster dose may eventually be needed. Currently, no booster dose is recommended. The WHO SAGE continues to review emerging data on the duration of protection.
Ervebo has been studied in a limited number of HIV-positive individuals who are on stable antiretroviral therapy and have adequate CD4+ T-cell counts. In these individuals, the vaccine appeared to be safe, though the immune response may be somewhat reduced compared to HIV-negative individuals. For people with advanced HIV disease or severely compromised immune systems, the decision to vaccinate should be made on a case-by-case basis, weighing the risk of Ebola exposure against the potential for reduced vaccine effectiveness and theoretical safety concerns associated with live vaccines.
All information is based on international regulatory assessments and peer-reviewed research: EMA Assessment Report for Ervebo (2019), FDA Prescribing Information for Ervebo (2019), WHO SAGE Interim Recommendations on Vaccination against Ebola Virus Disease, the Lancet publication of the ring vaccination trial results (Henao-Restrepo et al., 2017), and CDC ACIP recommendations. All medical claims follow the GRADE evidence framework with the highest available quality of evidence.
References
- Henao-Restrepo AM, et al. Efficacy and effectiveness of an rVSV-vectored vaccine in preventing Ebola virus disease: final results from the Guinea ring vaccination, open-label, cluster-randomised trial (Ebola Ca Suffit!). The Lancet. 2017;389(10068):505-518. doi:10.1016/S0140-6736(16)32621-6
- European Medicines Agency (EMA). Ervebo: EPAR – Product Information. Last updated 2024. EMA EPAR
- World Health Organization. WHO SAGE Interim Recommendations on Vaccination against Ebola Virus Disease (EVD). Geneva: WHO; 2019. WHO SAGE Recommendations
- U.S. Food and Drug Administration. Ervebo Prescribing Information. Silver Spring, MD: FDA; 2019.
- Centers for Disease Control and Prevention (CDC). Advisory Committee on Immunization Practices (ACIP) Recommendations for the Use of Ervebo. MMWR. 2020;69(3):76-79.
- Halperin SA, et al. Safety and immunogenicity of rVSVΔG-ZEBOV-GP vaccine in adults and children in randomised, double-blind, controlled clinical trials: a comprehensive review. The Lancet Infectious Diseases. 2022;22(5):e146-e158.
- World Health Organization. Ebola virus disease: Fact sheet. Geneva: WHO; 2024. WHO Fact Sheet
- Gsell PS, et al. Ring vaccination with rVSV-ZEBOV under expanded access in response to an outbreak of Ebola virus disease in Guinea, 2016: an operational and vaccine safety report. The Lancet Infectious Diseases. 2017;17(12):1276-1284.
Medical Editorial Team
This article was written by the iMedic Medical Editorial Team, comprising licensed physicians specializing in infectious disease, vaccinology, and tropical medicine. All content is reviewed according to the GRADE evidence framework and aligned with international guidelines from the WHO, EMA, FDA, and CDC.
Our editorial process includes systematic literature review, cross-referencing with primary regulatory documents, and independent medical review. We maintain strict editorial independence with no pharmaceutical company funding or sponsorship.
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