CDC uses the 3 month reference point when not to retest, if a person is asymptotic. He is well past 3 months now: March -> October (6 to 7 months). So, he should be quarantined if he now tested positive, with current guidance. Time will tell if 3 months could really mean 3 months plus “x” more months. Maybe future tests will be developed to determine if one is positive and infectious versus positive and not infectious. Hopefully he wasn’t a false positive, either!