I agree but I’m afraid I don’t see how the challenge trial is different. The standard trial lets people catch the virus somehow in the world. The challenge trial takes control of that. That’s the difference. That’s the only difference. And the only purpose is to get meaningful results faster.
I think the ethical conversation needs to be about the active infection of healthy people, thereby exposing them (actively is the key word, perhaps the only key word) to a pathogen. IMO the most relevant and informative comparison is to living kidney donors. Almost none of the comments in this thread so far are relevant to the question of whether to introduce challenge trials in place of standard trials.
As it happens, I was part of the process in which a loved one participated in the founding of a living kidney donor program, by being the first person (at that hospital) to volunteer to donate a kidney to a stranger. I will never forget what the surgeon said to my loved one: “This surgery will do you no good. It is my job to ensure that it does you no harm.” We all know that the surgeon could not promise that, and that my loved one was being exposed to significant potential harm.
I think we’re probably done here, but if we want to explore the ethical questions surrounding challenge trials, and the ethical weighting that they require, I will be interested in the conversation. I will expect that the conversation acknowledge the already-existing medical situations represented by living kidney donors, and that those who comment on SARS-CoV-2 challenge trials be willing to explain how living kidney donation is different.