Outbreaks of emerging infectious diseases, for which there are no vaccines or effective therapies, present unusual challenges to designing trials to evaluate new preventive or therapeutic products. Challenges may include such issues as the necessity to conduct studies in places with limited infrastructure for doing so, as well as the urgency to find safe and effective products as quickly as possible. Urgency may be due not only to the need to save lives, but also the need to obtain clear answers before the outbreak peters out. If the disease is highly fatal, ethical issues may arise regarding randomization and type of control to use.

The Ebola outbreak in West Africa in 2014 highlighted such challenges. Trial designs that were contemplated or implemented during the Ebola outbreak will be discussed, including the rationale, advantages, and limitations of each. Suggestions for other, innovative designs for potential use during future outbreaks will be welcome.