 A drug that is approved is said to be "safe and effective when used as directed".Some very rare limited exceptions to this multi-step process involving animal testing and controlled clinical trials can be granted out of compassionate use protocols, as was the case during the 2015 Ebola epidemic with the use, by prescription and authorization, of ZMapp and other experimental treatments, and for new drugs that can be used to treat debilitating and/or very rare conditions for which no existing remedies or drugs are satisfactory, or where there has not been an advance in a long period of time.The studies are progressively longer, gradually adding more individuals as they progress from stage I to stage III, normally over a period of years, and normally involve drug companies, the government and its laboratories, and often medical schools and hospitals and clinics.