Basic Profile
Ervebo is a single-dose vaccine used to prevent Ebola virus disease caused specifically by the Zaire ebolavirus.
It is also known as:
- rVSV-ZEBOV vaccine;
- Ebola Zaire Vaccine, Live;
- rVSVΔG-ZEBOV-GP vaccine.
It was the first Ebola vaccine to receive regulatory approval and World Health Organization prequalification. It is manufactured by Merck, known as MSD outside the United States and Canada.
Ervebo is approved for individuals aged one year and above in several major regulatory jurisdictions.
Composition and Working
Ervebo is a live recombinant viral-vector vaccine.
It uses a weakened vesicular stomatitis virus as a carrier. A gene encoding a surface glycoprotein of the Zaire ebolavirus is inserted into this carrier virus.
After vaccination, the immune system recognises the Ebola glycoprotein and produces:
- protective antibodies;
- cellular immune responses;
- immune memory.
The vaccine does not contain the complete Ebola virus and therefore cannot cause Ebola virus disease.
It is administered as a single intramuscular injection.
Use during Outbreaks
Ervebo is mainly recommended during outbreaks of Ebola disease caused by Zaire ebolavirus.
A major strategy is ring vaccination, under which vaccination is offered to:
- contacts of a confirmed Ebola patient;
- contacts of those contacts;
- healthcare and frontline workers;
- persons at high risk of exposure.
This creates a protective ring around confirmed cases and helps interrupt transmission.
Vaccination is used along with:
- rapid case detection;
- isolation and treatment;
- contact tracing;
- infection-control measures;
- safe and dignified burials;
- community engagement.
The vaccine is also maintained in an international emergency stockpile for rapid deployment during outbreaks.
Effectiveness and Safety
Ervebo has shown high protection during outbreak-related ring-vaccination studies, particularly when administered before exposure.
Common side effects include:
- pain or swelling at the injection site;
- headache;
- fever;
- fatigue;
- muscle and joint pain;
- nausea.
Since it is a live viral-vector vaccine, its use in severely immunocompromised persons requires careful assessment of risks and benefits.
Vaccination does not provide immediate protection. A person recently exposed to Ebola must still be monitored for symptoms during the full incubation period.
Ervebo protects only against disease caused by Zaire ebolavirus. It does not provide established protection against:
- Sudan virus;
- Bundibugyo virus;
- Taï Forest virus;
- Marburg virus.
Limitations and Public-Health Importance
Ervebo is an outbreak-control vaccine rather than a substitute for a strong public-health response.
Its major limitations include:
- protection limited to one ebolavirus species;
- requirement for specialised cold-chain arrangements;
- difficulty reaching populations in conflict-affected areas;
- community mistrust and vaccine hesitancy;
- limited evidence for some special populations;
- continued need for surveillance and infection prevention.
Its public-health importance lies in converting Ebola control from reliance solely on isolation and contact tracing to a strategy that also provides direct biological protection.
Conclusion
Ervebo is a live recombinant, single-dose vaccine that provides protection against Ebola virus disease caused by Zaire ebolavirus. It is most effective when used rapidly through ring vaccination alongside contact tracing, clinical care and strict infection-control measures.
