We’re told that viruses have "no cure," yet during pandemics people recover and are declared virus-free. I was bothered by that this morning and so when I searched it out, I learned that in many cases it’s actually the immune system clearing the virus, not a direct cure.

Okay, but I have more questions;

Why does it seem like many of the viruses that become global pandemics like COVID end up being the ones the immune system can eventually clear from the body, while others that spread less dramatically like HIV or herpes, can remain in the body permanently and one has to just cope and regulate till they die?

Why are the pandemic-type viruses that are abrupt and have less response time like temporary while the ones that don’t spread in the same "global way" stay permanent even after years of research?

I just don't get it.