Knox (calf) was placed on the reserve/COVID-19 list Saturday after testing positive, the Bills' official site reports.
Knox was already going to miss Sunday's game against the Jets due to his calf injury, so perhaps the bigger issue is that the team's tight end room is almost completely depleted, as fellow tight ends Lee Smith, Tommy Sweeney (currently on PUP list), and practice squad player Nate Becker have been defined to have been in close contact with Knox. They have all been placed on the Reserve/COVID-19 list and cannot take Knox's place in Sunday's game.