Ethical guidelines for deliberately infecting volunteers with COVID-19.

Global fatalities related to COVID-19 are expected to be high in 2020-2021. Developing and delivering a vaccine may be the most likely way to end the pandemic. If it were possible to shorten this development time by weeks or months, this may have a significant effect on reducing deaths. Phase II and phase III trials could take less long to conduct if they used human challenge methods-that is, deliberately infecting participants with COVID-19 following inoculation. This article analyses arguments for and against such methods and provides suggested broad guidelines for regulators, researchers and ethics committees when considering these matters. It concludes that it may be possible to maintain current ethical standards yet still permit human challenge trials in a context where delay is critical. The implications are that regulators and researchers need to work together now to design robust but short trials and streamline ethics approval processes so that they are in place when applications for trials are made.