You've been infected with COVID more times than you can count. The only reason you do not know that is because your immune system works.
YOU have COVID pretty much most of the time if you go to the store or whatever wherever. The reason you do not know this is because YOUR BODY IS FIGHTING THE VIRUS.
Once your body fights off the virus, that does not mean you never get the virus ever again.
You can get it again a week later. BUT YOUR BODY FIGHTS IT OFF AGAIN.
And AGAIN.
And AGAIN!
It is only when your immune system gets overwhelmed that you succumb to the virus and the problems it causes.
When I was a kid, I used to get strep throat every year for a spate of a few years. It was relentless. Eventually, my body learned how to fight the thing, and I never got it again. I never got a vaccine for it, but damn, I wish I had one so I didn't have to suffer the strep throat for those years.
Strep throat did not go away. It is still out there. But my body keeps fighting it off every time I get the virus from someone I catch strep throat from. It is the same as shit like Influenza, or COVID.
That's how this shit works, man.