look at the thread
I have a weird question for the actual experts on here. Is there some way after the fact to know if you had a COVID infection if you *also* had antibodies from having been vaccinated? That is, can a test distinguish vaccine-acquired and naturally-acquired antibodies?
— Nate Silver (@NateSilver538) August 5, 2021
one answer
Yes. The vaccine gives you antibodies for the S (spike) protein, but the tests can distinguish antibodies to the N (nucleocapsid) protein, which will be a feature of infection, but not of vaccination.
— Derek Lowe (@Dereklowe) August 5, 2021
Sad! 