Coach Mike Zimmer said Wednesday he doesn't know whether Thielen might be cleared to play this week.
"We'll just have to wait and see as the week goes on," Zimmer said.
Thielen was placed on the reserve/COVID-19 list Monday.
NFL Network's Tom Pelissero reported Tuesday that Thielen tested positive for COVID-19 but also had a negative test. Further testing will determine whether it was a false-positive.
If the star receiver did indeed test positive, he would miss Sunday's game. If it was a false-positive, he should suit up for the 4-6 Vikings.