Today, if there is a known vaccine treatment for a disease, the medical establishment considers it unethical to withhold that drug from trial participants, as would happen in a placebo group.
If someone knows they receive the placebo, then that undermines it being a placebo. You already have a control group…people who choose not to take the vax.
If someone knows they receive the placebo, then that undermines it being a placebo. You already have a control group…people who choose not to take the vax.
Only if psychological effects could impact the result. That doesn’t apply with vaccines, does it?
There can be psychological side effects, such as pain or anxiety.
So not efficacy
I dont think so. Not sure what you are trying to say here.