The effort was led by the organisation 1Day Sooner, which has been discussed in the forum before (also), and whose team and advisory board include a number of people associated with EA. See also the Washington Post op-ed Pandemic ethics: The case for experiments on human volunteers, by Richard Yetter Chappell and Peter Singer.
EDIT: Non-paywalled article
Update from Vox’s Future Perfect: UK challenge trial will infect volunteers with Covid-19 to test vaccines.