Per NFL Network's Tom Pelissero, Thielen was placed on the COVID list Monday. Thielen reportedly tested positive for COVID-19 but then tested negative, so it is unclear if the initial result was a false positive.
Thielen, who is half of one of the best wide receiver duos in the NFL along with rookie Justin Jefferson, leads the league with 11 touchdown receptions this season.
The 30-year-old Thielen is in the midst of his seventh NFL season, and he may be on track for his third career Pro Bowl nod.
After being limited to 10 games last season due to injury, Thielen has bounced back to rack up 49 receptions for 646 yards and 11 touchdowns in 10 games this season. The Minnesota native leads the Vikes in both catches and receiving touchdowns, and he is second to Jefferson in receiving yards, as the rookie paces the team with 848 yards.
Thielen entered the 2020 season with a great deal of pressure to step up after Minnesota traded wideout Stefon Diggs to the Buffalo Bills during the offseason, and the former Minnesota State star has been up to the challenge.
The 6'2", 200-pound wideout has four multi-touchdown games to his credit this season, including two touchdowns in each of the past two games.
He is coming off his best performance of the season with eight grabs for 123 yards and two scores last week against the Dallas Cowboys, although the Vikes were upset 31-28 as their three-game losing streak ended.
With Minnesota sitting at 4-6 on the season, Sunday's game against Carolina is huge in terms of the Vikings keeping their playoff hopes alive.
If Thielen does indeed miss the game, head coach Mike Zimmer's team could employ a run-heavy attack with the NFL's second-leading rusher, Dalvin Cook, carrying the load.
In terms of pass-catchers, Jefferson will step up as quarterback Kirk Cousins' No. 1 target, while Olabisi Johnson and Chad Beebe will be looked upon to play a bigger role at the receiver position.
Cousins could also incorporate tight end Kyle Rudolph more, especially since fellow tight end Irv Smith Jr. is doubtful with groin and back injuries.