system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If a one time infection by certain viruses (e.g. chicken pox) usually leads to immunity, why can other viruses recur in the same person countless times?
gpt
They can't, but what happens is that what we call the common cold for example isn't one virus. It's dozens and dozens of different strains of roughly the same virus. When you get sick and then heal from the cold, you have immunity against that particular strain. Not against the hundreds of others one that are still out there.