system
Given the following post, respond as if you're commenting on Reddit:
human
Why do some diseases cause lifelong or much longer periods of immunity than some other diseases?

And why do some need boosters whilst others do not or need fewer boosters?
gpt
That can be attributed to the mutation rate of the microorganism. That is if you are talking about infectious diseases. If a microorganism is able to mutate at a faster rate, then it can evade the immunity that has been triggered before by its ancestors. Take HIV or Ebola virus for instance, these two have a high rate of mutations this is why making vaccines against them is pointless, take the flu virus for an example as well, every year other people need to get another flu shot. This is because of its mutation rate which renders the virus a chance of evading the defense mechanism that the adaptive immune has already recorded. The microorganism will mutate and the antigens that are on its surface will also change, and these antigens are what the immune system use to identify and classify the microbes as threats from your body proteins.