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. 2020 May 11;221(11):1752-1756.
doi: 10.1093/infdis/jiaa152.

Human Challenge Studies to Accelerate Coronavirus Vaccine Licensure

Free PMC article

Human Challenge Studies to Accelerate Coronavirus Vaccine Licensure

Nir Eyal et al. J Infect Dis. .
Free PMC article


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.
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.

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    1. World Health Organization. DRAFT landscape of COVID-19 candidate vaccines. Accessed 20 March 2020.
    1. Spinney L. When will a coronavirus vaccine be ready? Guardian 17. March, revised 19 March, 2020.
    1. Centers for Disease Control and Prevention. People who are at higher risk for severe illness Accessed 8 March 2020.
    1. Begley S. Who is getting sick, and how sick? A breakdown of coronavirus risk by demographic factors. STATnews 3. March 2020. Accessed 1 April 2020.
    1. Novel Coronavirus Pneumonia Emergency Response Epidemiology Team. Vital surveillances: the epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19)—China, 2020. CCDC Weekly 2020; 2:113–22. - PubMed

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