It would take 2 weeks for IgG, but I have seen no evidence that the foreign viral m-RNA disintegrates.
This is from MSK debunking some of the myths going around.
https://www.mskcc.org/coronavirus/myths-about-covid-19-vaccines
From what I’ve read, the mRNA doesn’t go away. Once triggered by a wild virus, our bodies continue to produce the spike protein causing an excessive immune response and auto-immune disease or worse. But we shall see a few months down the road. Unfortunately lab animal tests were skipped in the development.