I'm in the trial. It's really exciting, not least because form a purely selfish point of view, I might be immune already! ...or not. But it's exciting either way! AMA?
What if something goes horribly wrong and the vaccine trial causes unwanted side effects? Why risk it, what are they paying you?
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.