Friend just told me that shortly after getting a vaccine, you should try your best to avoid getting sick as your body recovers from a vaccine.
This seems counter intuitive.
Opportunistic infections caused by other diseases are the result of your body spending resources to pursue one type of antigen while the second disease brings in completely different ones that you aren't ready to handle.
But in the case of vaccines, the disease it targets is supposed to have the same antigens. The fact that you already have a full immune response towards those antigens should, if anything, make it borderline impossible to get an actual infection shortly after being vaccinated.

I tried to research the topic, but search engines just think I'm talking about basic covid antivax questions and nothing actually answers my question.
Neither of us are antivax btw, we know it works, we just don't like governments making us take them.