The spike protein remains with you indefinitely.
How mRNA Vaccines Prevent COVID-19
“The immune system starts building an immune response and making antibodies,” says Aisha Langford, PhD, MPH, assistant professor in NYU Langone’s Department of Population Health. “And that’s how we train the immune system to recognize the spike protein, and that’s what protects us from being infected.”
Your body continues to produce antibodies until all the spike proteins have been destroyed. At the end of this natural immune process, your immune system has the knowledge it needs to recognize the spike protein and fend off future exposure to the virus. So if the virus enters the body, the immune system will identify and attack it."
In effect, you have modified your own genetic make-up to fight COVID without actually gaining immunity and without reducing transmissibility.
"The mRNA vaccines do not enter the nucleus of the cell, so it cannot change your DNA. After the mRNA delivers instructions to your cells, the body breaks it down and eliminates it."