Isn’t that the entire point of vaccines though. To essentially give a small amount of exposure to your immune system so that it

A) knows how to deal with the pathogen specifically

B) doesn’t go wild and kill the host in its own right whilst trying to figure out how to properly deal with the pathogen

My understanding is that without exposure you body kinda throws a lot of different types of t-cells at the issue. Once it kinda knows how to handle it, it just throws the specific variant of t-cells needed.