You still need to test for safety, that's definitely true. At least you know you have a viable candidate though I guess. People were actually volunteering for

You still need to test for safety, that's definitely true. At least you know you have a viable candidate though I guess. People were actually volunteering for a challenge trial for Covid prior to theraputics being available - because Covid actually is low-risk for the groups in the challenge trial (young people) and the vast majority of people recover. I don't think theraputics are necessary for a challenge trial, as long as there is sufficient benefit, the risk is sufficiently low, and volunteers are aware of the personal risks (aware this criteria is ambiguous!). HIV is incurable, however there are excellent therapeutics. Despite this, the prognosis of HIV is much worse than someone with Covid.