system
Given the following post, respond as if you're commenting on Reddit:
human
What happens if you get a vaccine for a disease you already have antibodies for?

With the Covid stuff going around, I'm sure there's some people who gained antibodies without realizing it.
Does nothing happen?
gpt
If you already have circulating antibodies from a prior infection (or a previous vaccine), your body would mount an immune response against the foreign antigen in the vaccine in a manner similar to how it deals with other pathogens your body encounters on a daily basis. This results in your body having greater stores of immune cells that can quickly produce antibodies against the infection. This is the principle behind "booster" shots or vaccines that are given in a series of multiple injections. It wouldn't result in any adverse effects beyond what you'd expect with a typical vaccine (that is, some injection site pain, headache, or muscle aches for a couple of days).