It actually is how the human immune system works, and in particular, there’s a huge amount of evidence that humoral immunity is protective and long lasting for Covid. Worrying about this is roughly the same degree of reasonable as worrying about getting any of the other common coronaviruses that circulate.

I know you’re not going to accept this, but there is quite literally no good evidence that boosters for Covid do anything for otherwise healthy people who have already been infected.

Regardless, the point is, if you won’t go to a language meetup because you’re worried about this, you’re likely doing far more damage to yourself from social isolation and anxiety than the virus would ever do to you. It’s time to live your life.