Stafford might be forced to skip the Lions' game against the Vikings on Sunday.
The Lions placed quarterback Matthew Stafford on the team's reserve/COVID-19 list, ESPN's Adam Schefter reports.
Schefter also reported Wednesday that Stafford had "high-risk, close contact from a non team member" on Monday.
According to Schefter, Stafford could come off the team's list and play in the Lions' game Sunday against the Vikings pending his test results.
Tom Pelissero of NFL Media reported Wednesday that Stafford will be eligible to play Sunday against Minnesota if he tests negative and asymptomatic.
The Lions will have to fly Stafford on a private plane to Minnesota because he will still under his five-day isolation window when the team departs Saturday, Pelissero reported. Stafford will also not be able to practice all week.
Before Stafford's placement on the list Wednesday, he was on the list for a day during the summer after a false positive test.
Detroit did not report any positive COVID-19 tests Wednesday morning. On Tuesday, however, the Lions put linebacker Jarrad Davis on the team's reserve/COVID-19 list.
In the Lions 41-21 loss to the Indianapolis Colts on Sunday, Stafford went 24-of-42 for 336 yards with three touchdowns and one interception. Through seven games, Stafford has thrown for 1,916 yards and 13 touchdowns.
If Stafford is not able to go on Sunday, quarterback Chase Daniels will start against the Vikings. Detroit (3-4) sits third in the NFC North and ahead of the Vikings (2-5).
Kickoff for Sunday's game is set for 1 p.m. ET.