He was positive again by way of a nasal swab PCR test. Doesn’t even really mean anything. Doesn’t mean he was “infected”, assuming the test was accurate. And there will be residual immunity for most likely forever. You are coming into contact with numerous viruses every single day. If we tested for any of them by way of PCR we would be finding positive tests for just about everything. As long as we continue to test people for no real reason we are going to find “positive cases” forever.