I was a vaccine trial participant and got injected 6 months ago. I'm still alive. AMA.
They want to keep the trial running as long as possible to get longer-term data (understandable) but it is also potentially unethical to not tell someone if they got a placebo if they are at-risk and a known-good vaccine is otherwise available. I'm in the UK where they are already vaccinating thousands of people everyday with the Pfizer one, so I expect them to figure out the unblinding details very shortly.
FWIW, I usually get no side effects with a flu shot but others get more so I'm sure it varies person to person.