Ebola vaccines are vaccines either approved or in development to prevent Ebola. As of 2022, there are only vaccines against the Zaire ebolavirus. The first vaccine to be approved in the United States was rVSV-ZEBOV in December 2019. It had been used extensively in the Kivu Ebola epidemic under a compassionate use protocol. During the early 21st century, several vaccine candidates displayed efficacy to protect nonhuman primates (usually macaques) against lethal infection.
Vaccines include replication-deficient adenovirus vectors, replication-competent vesicular stomatitis (VSV) and human parainfluenza (HPIV-3) vectors, and virus-like nanoparticle preparations. Conventional trials to study efficacy by exposure of humans to the pathogen after immunization are not ethical in this case. 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.
Approved
rVSV-ZEBOV
VSV-EBOV or rVSV-ZEBOV, sold under the brand name Ervebo, is a vaccine based on the vesicular stomatitis virus which was genetically modified to express a surface glycoprotein of Zaire Ebola virus. In November 2019, the European Commission granted a conditional marketing authorization. The WHO prequalification came fewer than 48 hours later, making it the fastest vaccine prequalification process ever conducted by WHO. It was approved for medical use in the European Union in November 2019. It was approved for medical use in the United States in December 2019.
The most common side effects include pain, swelling and redness at the injection site, headache, fever, muscle pain, tiredness and joint pain. In general, these reactions occur within seven days after vaccination, are mild to moderate in intensity and resolved in less than a week.
It was developed by the Public Health Agency of Canada, with development subsequently taken over by Merck Inc. In October 2014, the Wellcome Trust, who was also one of the biggest UK founders, announced the start of multiple trials in healthy volunteers in Europe, Gabon, Kenya, and the US. The vaccine was proven safe at multiple sites in North America, Europe, and Africa, but several volunteers at one trial site in Geneva, Switzerland, developed vaccine-related arthritis after about two weeks, and about 20–30% of volunteers at reporting sites developed low-grade post-vaccine fever, which resolved within a day or two. Other common side-effects were pain at the site of injection, myalgia, and fatigue. The trial was temporarily halted in December 2014 due to possible adverse effects, but subsequently resumed. , a Phase III trial with a single dose of VSV-EBOV began in Liberia after a successful Phase II study in the West African country. On 31 July 2015, preliminary results of a Phase III trial in Guinea indicated that the vaccine appeared to be "highly efficacious and safe." The trial used a ring vaccination protocol that first vaccinated all the closest contacts of new cases of Ebola infection either immediately or after 21 days. Because of the demonstrated efficacy of immediate vaccination, all recipients will now be immunized immediately. Ring vaccination is the method used in the program to eradicate smallpox in the 1970s. The trial will continue to assess whether the vaccine is effective in creating herd immunity to Ebola virus infection. In December 2016, a study found the VSV-EBOV vaccine to be 95–100% effective against the Ebola virus, making it the first proven vaccine against the disease.