Yeah, you are right. I realized it, it just works when we log in. If we just visit the forum without log in, the mark isn't visible.
It's not a vaccine, but a natural antibody.
When you log out, the virus dies. So when you are very close to die then just log out and you are cured 100%.
Virus dies and your account is over. "Out of online"
I can't try it yet because my account is still healthy. It seems my account has a strong defense and outperformed antibody. But maybe infected very soon after I quote your post above. Let's see!!