coffee, a good question. I’ve looked at recall information. It seems that problems with vaccines are typically found quickly. That is, there might be short-term side effect after vaccine uptake, but not long-term. It seems to make sense in terms of how immunity reacts to a threat. If there are long-term vaccine cases, please point me to them.
As to short-term, there is a lot of data by now. First, original Phase 3 trials are now more than a year old. So, they would have safety info. Second, real world tests are now done on millions of people and statistics collected.
That said, there are some decisions that are made as pressed by time and conservative approach – such as having, for now, doses for younger adults and children being same as for older people.
Immune response seems to be universally higher with younger age, and risk lower… These decisions are based on Phase 3s being set up for a reasonably high dose to pass the test from the first attempt, and lack of data on lower doses. Whenever FDA authorizes 10 mcg for children < 12 y.o. (v 30 mcg for adults) or when regular authorization will be available, hopefully it will be possible for all young people, even above ba mitzva to use lower doses.