You're describing T-cell immunity. Which is the missing part when the fear-mongering media says that antibody levels drop after X months. So what? Memory B cells and T cells kick back in as soon as your body encounters the virus again.That happens. As I stated earlier in this thread, my cousin was in a house with 9 other people that all had Covid symptoms and positive tests and never tested positive or showed any symptoms and never developed antibodies in the month after exposure. I won't say there were 9 cases as only one of the 9 required medical care though she ended up in the ICU. Every major contagion in history has some people that for one reason or another seems to have some level of natural immunity. Typhoid, Black Death, Spanish Flu, etc all had people that came through unscathed despite being surrounded by it. Of course it could just be a fluke and not anything special about the human, but I've found that interesting. There are some research groups (primarily in India) that are studying people that have shown some levels of natural immunity (meaning no antibodies but still some reason they do not seem to catch the virus). They are trying to determine if there is something deeper in the systems of the people that protects them. To my knowledge they've not published anything as of yet, but I'm keeping an eye out for those.
There's obviously some immunity mechanism keeping re-infection to infinitesimal levels despite the drumbeat of bullshit to the contrary.