Ebola is a rare hemorrhagic fever disease caused by infection with one of the Ebolavirus strains (there are currently five known species of this virus). At this time, there are no vaccines or drugs that have been approved by the U.S. Food and Drug Administration (FDA) to prevent or treat Ebola in humans. The National Institutes of Health (NIH) and several companies have experimental Ebola vaccines and treatments in development, some of which have been in development for many years, but approved medicines that effectively treat or prevent Ebola may be years away.
Vaccines are typically given to people before they are exposed to a virus or bacteria. They stimulate the production of antibodies to create an immune system response if the person were to become infected later. Currently, three experimental vaccines are in Phase 1 clinical trials, one by each of GlaxoSmithKline (in collaboration with the NIH’s National Institute of Allergy and Infectious Diseases), NewLink Genetics, and Crucell (a subsidiary of Johnson & Johnson’s Janssen Pharmaceuticals). Other experimental vaccines are in earlier stages of development. The Department of Health and Human Services expects Phase 2 clinical efficacy trials on vaccine candidates to begin in 2015.
A therapeutic drug is given to treat people who are already infected and sick with a virus or disease. With respect to Ebola treatments, several companies are in the process of developing and testing therapeutic drugs, but none have been FDA-approved as effective treatment for humans. Most of the experimental treatments are in the pre-clinical phase of development, with just three that are currently undergoing human clinical trials. On October 16, 2014, Chimerix, Inc. was cleared to begin Phase 2 clinical trials with its Brincidofovir treatment. In March 2014, TKM-Ebola, a drug being developed by Tekmira Pharmaceuticals, was given Fast Track designation by the FDA and is currently in Phase 1 clinical trials. Sarepta Therapeutics’ AVI-7537 drug candidate is also undergoing Phase 1 clinical trials.
While FDA approval of an Ebola vaccine or therapeutic drug for marketing and use in the United States may not occur in the near future, there is regulatory flexibility to allow access to experimental drugs and vaccines prior to approval. Specifically, there are several mechanisms available for pre-approval and the accelerated use of vaccines and therapeutic drugs, such as Expanded Access to Investigational Drugs for Treatment Use, Emergency Use Authorization, orphan drug designation and the use of enforcement discretion based on compassionate use.