Because if you cannot interpret the data from a group, then what good is the group?
Not that these people were infected and exposed to different things in their daily lives?
So if some of your placebo group got naturally infected during the course of the 12-18 month phase 3 and naturally developed antibodies, that invalidates your vaccine or shows contamination in your study?
With a placebo group that yields uninterpretable data, you still don't know what's wrong and basically have to explain away everything you see. If the placebo group developed antibodies, then it's because they developed them naturally; if they got sick, then it's because they got exposed to something, etc...
Do you know the purpose of randomization in a randomized controlled trial?
It implies that if you find some subject in your placebo group got naturally infected, you need to assume that your vaccine group has been exposed to the same risk.
And if you know your vaccinated sample is at risk of developing antibodies from outside contact, not just from the vaccine you are testing, does that ring any bells when you try to conclude your vaccine's efficacy?
It is exactly because there is a placebo group that you can be alerted to such contamination.
All data is clue, even if it's a clue that says "you messed up, you should start the trial again", it is still valuable because you may have avoided killing people with an ineffective vaccine. When finding antibodies in your placebo group, if you simply dismiss it as "uninterpretable" and attempt to "solve" the problem by cancelling the placebo group, you should not be doing medical research.
Fortunately, professionals do not learn how to do medical research from ostriches.
Human challenge trials lasting 2 months in a secure facility solves all of these issues.
I'm afraid this is wishful thinking, based on what I have explained in previous posts as well as predictions on vaccine development time from the world's top experts. It would be great if true, but unlikely.
For mice, it's basic. For people, you need to think instead of opening a textbook, reading that you need control group, so you do a control group. For me, a person, it's disrespectful to haul my ass into the hospital to get my blood time and time again after injecting me with saline when you have something that can potentially vaccinate me.
I didn't say the phase 3 needs to be nixed; I said human challenge trial can be done in parallel to get something out there ASAP. Safety is already established in phase 2, which is pre-human challenge trial. Reliability will be determined in the human challenge trial, over a smaller but controlled group. In the meantime, it's better to have something that at least partially works (or completely) than to have nothing at all until phase 3 ends in 12-18 months.
I simply do not agree with you or Bltzio that this is a standard case that defaults to the textbook approach to experimentation. I think this is a very urgent situation and executive decisions need to be made to speed things up drastically.
Like what Bltizo said, when you enroll in a clinical trial you're not there to get immunity, you are there to help conduct a research. If you find the possibility of being given a placebo disrespectful, then just don't volunteer yourself, I'm sure there are plenty of people who are more understanding and willing to help.