This is a Human Challenge Trial: have vaccinated participants exposed to either covid or placebo (rhinovirus)! There are heavy ethical dilemmas here, even when

This is a Human Challenge Trial: have vaccinated participants exposed to either covid or placebo (rhinovirus)! There are heavy ethical dilemmas here, even when using young and healthy candidates. IIRC there was one Human Challenge Study being run in the UK, though they've been awfully quiet for months.