General Information

Ervebo is a vaccine indicated for the prevention of disease caused by Zaire ebolavirus.

Ervebo is specifically indicated for the prevention of disease caused by Zaire ebolavirus in individuals 18 years of age and older.

Ervebo is supplied as a solution for intramuscular injection.  Administer a 1 mL dose of Ervebo intramuscularly, preferably in the deltoid area of the nondominant arm. Discard unused portion.

Clinical Trials

FDA Approval

The FDA approval of Ervebo was based on the following studies:

Clinical efficacy

The efficacy of Ervebo was assessed in Study 3 (Ring vaccination study). This was an open-label, randomized cluster (ring) vaccination study conducted in the Republic of Guinea during the 2014 outbreak. Each cluster was composed of contacts and contacts of contacts of individuals with laboratory-confirmed Ebola virus disease (EVD). Clusters were randomized to receive either an “immediate” vaccination or a 21-day “delayed” vaccination. In the primary efficacy analysis, 3,537 subjects ≥18 years of age were considered contacts and contacts of contacts of an index case with laboratory-confirmed EVD. Of these, 2,108 were included in 51 immediate vaccination clusters, and 1,429 were included in 46 delayed vaccination clusters. The median age of subjects in the primary efficacy analysis was 40 years. The majority were male, comprising 70.4% and 70.3% in the randomized immediate and delayed clusters, respectively. In the primary efficacy analysis, the number of cases of laboratory-confirmed EVD in subjects vaccinated in immediate vaccination clusters was compared to the number of cases in subjects in delayed vaccination clusters. Cases of EVD that occurred between Day 1 0 and Day 31 post-randomization of the cluster were included in the analysis. Vaccine efficacy was 100%; no cases of confirmed EVD were observed in the immediate vaccination clusters, and 10 confirmed cases of EVD were observed in a total of 4 delayed vaccination clusters between Day 10 and Day 31 post-randomization.

Clinical Immunogenicity:

A measure of the immune response that confers protection against EVD is unknown. Three studies assessed antibody responses to Ervebo (Study 1, Study 2 and Study 4), including 477 subjects in Liberia, 506 subjects in Sierra Leone, and 915 subjects in the US, Canada, and Spain (n= 865 US subjects). Zaire ebolavirus (Kikwit) GP-specific immunoglobulin G (IgG) was detected by enzyme linked immunosorbent assay (GP-ELISA). Vaccine virus neutralizing antibody was detected by a plaque reduction neutralization test (PRNT). Antibody responses among subjects in the study conducted in the US, Canada, and Spain were similar to those among subjects in the studies conducted in Liberia and in Sierra Leone.

Side Effects

Adverse effects associated with the use of Ervebo may include, but are not limited to, the following:

• injection-site adverse events, including injection-site pain, swelling and redness
• headache
• feverishness
• muscle pain
• fatigue
• joint pain
• nausea
• arthritis
• rash
• abnormal sweating

Mechanism of Action

Immunization with Ervebo results in an immune response and protection from disease caused by Zaire ebolavirus. The relative contributions of innate, humoral and cell-mediated immunity to protection from Zaire ebolavirus are unknown.

Additional Information

For additional information regarding Ervebo or Zaire ebolavirus, please visit Merck's web page.