A lot of safety data has been done in the trials like never before and this is still on going as is the trials. long term study into immunity are on going Oxford uni I believe has been testing anti body levels for a good 6 months in NHS staff. Again this is on going and more will be done over time. Given the high stakes in this and the high profile of it. This vaccine has been under the spot light like no other. No one involved in it want's to be seen as failing. Covid like no other has so much money thrown at it, so much science and medical time given to it, so much data sharing and so much work into. That's way the time frame for a vaccine has been able to come right down. It's also benefitted from advancements in science that even 5 years ago we did not have. Yes we still don't know everything about covid but we know a hell lot more about than we did. Approval will only be given once it's safe to do so regulation now was never in place years ago never mind decades ago. Until the full and final information is in and it's peer reviewed no one knows if any of this will work or not.
One thing I can say never mind the government spin the vaccination program will take as long as it takes. It can only go at the speed it can go no matter what is thrown at it.
Being cautious is understandable so much about covid has laid bare day to day public health, science, Medical and clinical matter. Which for most pepole they never had a clue happen (eg.contact tracing.) Only for the mass media, the internet, and governments to pick over, cherry pick and take total out of context. That's way the messaging around this has to be bang on. Simple questions a straight reply. Unless a real change in government messaging happens and they have confidence in this. It will never work and the wheel will just go keep going round and round.