It's worth pointing out that during a pandemic, while participating in a trial does carry a risk, so does not participating. A participant has some substantially greater probability* than the general population of avoiding an infection which apparently carries a risk of death or long term debilitating effects.
* You'll have to incorporate the probability of being in the control group, of course, but the overall probability is still significant.
Participating also carries risks beyond simply that of the vaccine. Being exposed to any kind of healthcare setting is extremely dangerous right now. I'm taking part in the Moderna trial, and honestly I'm considering dropping out before the second injection. The risk of going into a clinic multiple times where I hear people coughing all over the place is starting to seem unacceptable to me given that I'm fairly certain I've been given the placebo.
My life can begin to go back to normal potentially months before it otherwise would.
Howso? Socialization is a multi-party dynamic. Folks might not care/believe you if you state 'I'm vaccinated' until it's widely accepted.
You'd have to ask my friends. But they're all more interested and curious than suspicious!
It's interesting because that's, not once, ever been a concern. If people don't want to spend time with me until vaccination is more widespread, then that's fine. But the intersection between those who don't trust that I've been vaccinated and those who don't trust vaccination anyway is probably pretty large...