The Ethics of Human Challenge Trials Using Emerging Severe Acute Respiratory Syndrome 2 Variants

Abstract

The world’s first COVID-19 human challenge trial using the D614G strain of SARS-CoV-2 is underway in the United Kingdom. The Wellcome Trust is funding challenge stock preparation of the Beta and Delta variant for a follow-up human challenge trial, and researchers at hVIVO are considering conducting these trials. However, little has been written thus far about the ethical justifiability of human challenge trials with SARS-CoV-2 variants of concern. We explore two specific characteristics of some variants that may initially be thought to make such trials unethical and conclude that SARS-CoV-2 variant challenge trials can remain ethical.

Pandemic vaccine testing: Combining conventional and challenge studies

“…8,[10][11][12][13][14][15][16] Indeed, some were puzzled that the United Kingdom is launching challenge trials after conventional trials have completed successfully. 17 This commentary concerns circumstances when either design would otherwise be permitted as a standalone (an assumption that in our views obtained 8,18,19 and will continue to obtain 20 in COVID); it argues that in such circumstances, both now and in some future pandemics, it may be even more advisable to combine conventional and challenge testing for surer, faster, and more comprehensive vaccine assessments and fuller understanding of the infection and the disease.…”