For such situations, the US Food and Drug Administration (FDA) has established the "animal efficacy rule" allowing licensure to be approved on the basis of animal model studies that replicate human disease, combined with evidence of safety and a potentially potent immune response (antibodies in the blood) from humans given the vaccine.

Clinical trials involve the administration of the vaccine to healthy human subjects to evaluate the immune response, identify any side effects and determine the appropriate dosage.

[25] On 31 July 2015, preliminary results of a Phase III trial in Guinea indicated that the vaccine appeared to be "highly efficacious and safe.

[9] The most commonly reported side effects were pain, swelling and redness at the injection site, as well as headache, fever, joint and muscle aches and fatigue.

[33] In November 2019, the European Commission granted a conditional marketing authorization to Ervebo (rVSV∆G-ZEBOV-GP, live)[18][34][4] and the WHO prequalified an Ebola vaccine for the first time.

[37] This finding, detailed in a study published in The Lancet Infectious Diseases, marks the first peer-reviewed evaluation of the vaccine, Ervebo, under real-world conditions.

[46] As a precautionary measure for individuals at imminent risk of exposure to Ebola virus (for example healthcare professionals and those living in or visiting areas with an ongoing Ebola virus disease outbreak), an extra Zabdeno booster vaccination should be considered for individuals who completed the Zabdeno-Mvabea two-dose vaccination regimen more than four months ago.

[50] In 2017, the China Food and Drug Administration (CFDA) announced approval of an Ebola vaccine, co-developed by the Institute of Biotechnology of the Academy of Military Medical Sciences and the private vaccine-maker CanSino Biologics.

[54] In September 2014, two Phase I clinical trials began for the vaccine cAd3-EBO Z, which is based on an attenuated version of a chimpanzee adenovirus (cAd3) that has been genetically altered so that it is unable to replicate in humans.

[62] The cAd3 vector has a DNA fragment insert that encodes the Ebola virus glycoprotein, which is expressed on the virion surface and is critical for attachment to host cells and catalysis of membrane fusion.

[64][65] In December 2014, University of Oxford expanded the trial to include a booster vaccine based on MVA-BN, a strain of Modified vaccinia Ankara, developed by Bavarian Nordic, to investigate whether it can help increase immune responses further.

In animal studies, a useful immune response was induced and was found to be enhanced ten to a hundred-fold by the company's "Matrix-M" immunologic adjuvant.

As of February 2015[update], Novavax had completed two primate studies on baboons and macaques and had initiated a Phase I clinical trial in Australia.

The Lipid nanoparticle (LNP)-encapsulated siRNAs rapidly adapted to target the Makona outbreak strain of EBOV and are able to protect 100% of rhesus monkeys against lethal challenge when treatment was initiated at three days post-exposure while animals were viremic and clinically ill.[70] The top line Phase I human trial results showed that the adjuvanted Ebola GP Vaccine was highly immunogenic at all dose levels.

[71][73] Vaxart Inc. is developing a vaccine technology in the form of a temperature-stable tablet which may offer advantages such as reduced cold chain requirement, and rapid and scalable manufacturing.

[74] A study published in Science during March 2015, demonstrated that vaccination with a weakened form of the Ebola virus provides some measure of protection to non-human primates.

[76] In September 2019, a study published in Cell Reports demonstrated the role of the Ebola virus VP35 protein in its immune evasion.

A recombinant form of Ebola virus with a mutant VP35 protein (VP35m) was developed, and showed positive results in the activation of the RIG-I-like receptor signaling.

[79] According to local media reports, the Guinean government authorized the commencement of the trials on 9 August 2017, at the Rusal-built Research and Diagnostic Center of Epidemiology and Microbiology in Kindia.

[81] In 2014, Credit Suisse estimated that the US government will provide over $1 billion in contracts to companies to develop medicine and vaccines for Ebola virus disease.

[82] Another company, Emergent BioSolutions, was a contestant for manufacturing new doses of ZMapp,[citation needed] a drug for Ebola virus disease treatment originally developed by Mapp Biopharmaceutical.