Vaccines got us rid of smallpox among other things. Any possible effects vaccines *might* have are small in comparison on the population level. You may get a vaccine that kills you for a disease that you weren’t at risk of acquiring. But that is rare. Nevertheless, more research is welcome. You are looking for serious adverse reactions for a massive amount of people that show no signs in the first year after vaccination. Sounds unlikely to me. There is little pressure to fund such studies.