There are currently no vaccines or anti-viral treatments of proven effectiveness against the Ebola virus disease.
Symptoms of the disease are treated as they appear. Early treatment improves survival. The following basic treatment measures can be adopted to significantly improve chances of survival:
- Administer intravenous fluids (IV) and maintain the fluid and electrolyte balance (body salts)
- Maintain adequate levels of oxygen and blood pressure
- Treat other infections that may arise, as well as other complications
Recovery of the patient depends on their own immune response. People who recover from an Ebola virus infection produce antibodies that may last for at least 10 years.
What experimental vaccines and treatments are being tested?
Various experimental vaccines have been tested and their effectiveness has been shown in animals but their effectiveness has yet to be proven in official studies in humans. Experimental treatments with antiviral drugs and specific antibodies have also produced inconclusive results as to their effectiveness. The results obtained from experimental models suggest they are capable of providing a significant degree of protection. In any case, the immune response of the patients themselves plays a highly important role in their recovery.
On 11 August, a group of experts gathered by the WHO agreed that the use of experimental medicines and vaccines is ethically acceptable given the exceptional circumstances surrounding the EVD epidemic.
Two experimental vaccines currently exist for clinical use that can be applied to stage 1 clinical trials prior to their authorisation:
- (cAd3-ZEBOV) obtained by GlaxoSmithKline in collaboration with the US National Institute of Allergy and Infectious Diseases. It uses a chimpanzee adenovirus into which an Ebola virus gene has been inserted.
- (rVSV-ZEBOV) obtained by the Public Health Agency of Canada in Winnipeg. The marketing licence is owned by a US company, NewLink Genetics, based in Ames (Iowa). It uses an attenuated vesicular stomatitis virus (a livestock disease) in which one of the genes has been replaced by an Ebola virus gene.
Treatments with antiviral drugs:
Antiviral drugs are those that interfere with the multiplication of a virus. These treatments can be effective during the symptomatic stage of diseases caused by a virus. Various pharmaceutical laboratories around the world are working on a number of research initiatives on this type of treatment to combat Ebola. Some of the most important of these projects include:
- TKM: This is an interfering RNA that blocks the genetic machinery of the Ebola virus. It is being manufactured by the Canadian pharmaceutical company Tekmira. Production is limited for the time being and there is no information as yet on current availability.
- Other experimental antivirals include Favipivavir, Interferon, BCX4430, Brincidofovir and AVI-7537.
- In any case, these are experimental treatments; there is no data on their effectiveness and their availability is not guaranteed.
Treatments with specific antibodies (immunotherapy):
Immunotherapy consists of supplying the patient with specific antibodies against the virus producing the disease. This has been proven effective against other diseases during the very early stages of infection but not so at later stages. Treatment is based on the ability of the specific antibodies to block viral infectivity.
The current alternatives in terms of the Ebola virus disease are the following:
- ZMAPP: This is a mixture of monoclonal antibodies against the Ebola virus developed by Mapp Biopharmaceutical. These antibodies are capable of effectively neutralising viral infectivity. Its availability is highly limited although efforts are being made to increase production.
- Other alternatives: the group of experts gathered by the WHO on 11 August 2014 agreed on assigning priority to the research taking place on treatments that use plasma taken from people who have overcome the disease (convalescent patients). Said plasma is obtained via donation from these convalescent patients and contains specific antibodies against the virus.
What are the expectations of finding effective vaccines and treatments against the Ebola virus disease?
For now, there is no clear timeline on the development of such vaccines and treatments. The roadmap established by the WHO for development of already existing vaccines (cAd3-ZEBOV and rVSV-ZEBOV) is as follows:
- October 2014: The procedures for assessing and sharing data instantly will have been prepared and agreed, and stage 1 clinical trials will have begun.
- October and November 2014: Common protocols (including stage 2 studies) at the various research centres will have been agreed. Preparation of said research centres for starting stage 2 studies will need to begin as soon as possible.
- November and December 2014: Initial safety data from stage 1 tests will have been obtained.
- January 2015: Doses of vaccines prepared according to manufacturing best practices will be made available as soon as possible for use in the stage 2 studies.
- January and February 2015: Stage 2 studies in the affected countries and other countries, as necessary, will have been approved and begun.
Once data on effectiveness are obtained, large-scale vaccination will be planned, including financing, assignation and usage systems.
No specific timeline can be announced with regard to the antiviral and immunotherapy treatments.