Samuel was already ruled out due to a hamstring injury.
Perhaps adding insult to injury, the investigation has revealed that Bourne may have violated NFL rules surrounding the wearing of a face mask.
Masks are required for all team and league personnel, players included, while traveling to and from games. They also are required inside all team facilities with the exception of practices and workouts.
49ers head coach Kyle Shanahan was fined $100,000 after Week 2 for improperly wearing a face mask. The team was fined an additional $250,000 for the violation.
NFL players are also strongly encouraged to wear masks on the sidelines during games. However, that is different for the 49ers and Buffalo Bills. Players on those teams must wear masks on the sidelines of their home stadiums due to local restrictions.
There was some speculation by NBC Sports Bay Area that Bourne's test may have been a false-positive after a subsequent test returned negative. Both Ian Rapoport of NFL Network and Adam Schefter of ESPN doubt that to be the case, though.