Tretter (illness) was placed on the reserve/COVID-19 list Thursday, Nate Ulrich of the Akron Beacon Journal reports.
Tretter announced via his personal Twitter feed that he has tested positive for the virus but is vaccinated, so he'll have a chance to play Saturday. If he's sidelined in Week 16, Nick Harris will likely draw the start at center as the Browns face off with the Packers on Saturday.