Why do you gain resistance to some illnesses after having them but not others?
In: 1
tl;dr nobody knows (yet)
You gain a resistance to every virus, bacteria, and fungus that your body encounters. Sometimes you gain a really strong resistance that lasts for a lifetime (like measles) and sometimes you get a really pathetic resistance that wears away every two years (like RSV). Sometimes you don’t become immune, but the second infection is way less likely to kill you (like malaria or COVID-19). Sometimes you become mostly immune, but the disease is really good at hiding from your immune system so it establishes a chronic infection, like hepatitis C, HIV, or syphilis.
In some cases, we know the reason why. HIV and herpesviruses stay around forever because they hide inside of your cells and live there forever, so even if your immune system gets good at fighting, it just can’t eradicate every last virion. In some cases the reason is unclear. Immunity to RSV is very short-lived and I don’t think anybody knows why. Or for the flu, it’s because the flu mutates very quickly.
Latest Answers