Human Challenge Studies to Accelerate Coronavirus Vaccine Licensure

Abstract

Controlled human challenge trials of SARS-CoV-2 vaccine candidates could accelerate the testing and potential rollout of efficacious vaccines. By replacing conventional phase 3 testing of vaccine candidates, such trials may subtract many months from the licensure process, making efficacious vaccines available more quickly. Obviously, challenging volunteers with this live virus risks inducing severe disease and possibly even death. However, we argue that such studies, by accelerating vaccine evaluation, could reduce the global burden of coronavirus-related mortality and morbidity. Volunteers in such studies could autonomously authorize the risks to themselves, and their net risk could be acceptable if participants comprise healthy young adults, who are at relatively low risk of serious disease following natural infection, if they have a high baseline risk of natural infection, and if during the trial they receive frequent monitoring and, following any infection, the best available care.

Keywords: coronavirus; ethics; human challenge studies; randomized controlled trials; risk-taking; vaccines.

Figure 1.

The process to vaccine licensure through a controlled human challenge trial and large study to assess short-term safety (black) compared to the conventional phase 3 trial route to licensure (grey). Submission for licensure could occur substantially earlier with a controlled human challenge trial.