last year is first time humans had ever taken mRNA, it's a new technology of sorts.No idea. We don't know anything about the possible long term effects of the vaccine and very little about the possible long term effects of the Covid virus itself. Only time will tell. However, we do know that the vaccines have not gone through a full approval process yet and that they were developed unlike previous vaccines.
last i heard Novavax was expected to get EUA this month. it's plant based DNA from a tree bark in south america.
one in UK has completed phase 2 and is a traditional vaccine made from dead virus cells.