you don't know how vaccines actually work, so let me simplify it for you again! :)
so, imagine your body has a bunch of cops right, your white blood cells, and they need training. their usual training would just be fighting off the usual pathogens. but what about big big ultra bad pathogens? they need to prep for it. how do you prep? a vaccine. vaccines act as training/boxing dummies for those cops. get it yet? good.