The Ethics of Human Challenge Trials Using Emerging SARS-CoV-2 Virus Variants

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 variant (B.1.351) for a follow-up human challenge trial, and researchers at Imperial College London are considering conducting that trial. However, little has been written thus far about the ethical justifiability of human challenge trials with SARS-CoV-2 variants of concern. While vaccine resistance as such does not increase risks for volunteers in COVID-19 challenge trials, 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.