I think it's more that placebo studies of vaccines could be unethical. Vaccines are preventative treatment. A placebo study would mean that, say, we give the vaccine to 50, and a placebo to 50, and then wait some time (or, for much more unethical, deliberately inject people with the virus), and compare the results.
For something like the common flu, this might be fine, but for something as dangerous as measles, this can be deadly.
I am interested to hear from someone knowlesgeable how vaccines are supposed to be tested.
I think this misrepresents the conversation that actually happened. Paraphrasing, it was something like this:
While it could be taken from that convo that Trump did say he doesn't know if he should follow the constitution, I think that it is clear that he was probably saying something like "I don't know where the Constitution stands on due process."
I'll say though, it is crazy for him to say he doesn't know what the Constitution says. I know he probably does that for legal reasons. Anyway, for a president who swore to follow the constitution seemingly not knowing anything about the constitution is preposterous, to say the least.