He becomes the second NFL quarterback to be placed on the reserve list over coronavirus concerns after Atlanta Falcons' Danny Etling, according to NFL Network.
Stafford, a starting quarterback for the Lions, had his streak of 136 straight regular-season starts snapped last season due to a back injury.
The 32-year-old can be activated off the reserve list once he receives medical clearance, which requires him to pass NFL Players' Association (NFLPA) treatment and protocols.
Under the agreement approved by the league and NFLPA last month, players have the choice to opt out of the 2020 season due to the pandemic.
Over 30 players have chosen to miss the campaign as NFL training camps opened across the country this week, with the season scheduled to start on Sept. 10. (Reporting by Hardik Vyas in Bengaluru Editing by Toby Davis)