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Tom Brady is one of the 40 million Americans who have tested positive for COVID-19 so far. Brady recently told Rick Stroud of the Tampa Bay Times that he contracted the virus shortly after the Buccaneers' championship boat parade following Tampa's 31-9 win over the Chiefs in Super Bowl LV. 

Brady is one of the 176 million Americans who are fully vaccinated. Brady's team is one of two NFL teams (the Atlanta Falcons being the other) to announced that their entire roster is vaccinated. But despite the league's reported 93% vaccination rate, Brady believes that the virus will present more of a league-wide challenge in 2021 than in 2020, before vaccinations were available. 

"I think it's going to be challenging this year," Brady said, via Jelani Scott of "I actually think it's going to play more of a factor this year than last year, just because of the way what we're doing now and what the stadium is going to look like and what the travel is going to look like and the people in the building and the fans.

"It's not like last year, although we're getting tested like last year. It's going to be, I definitely think guys are going to be out at different points and we've just got to deal with it."

To the average fan, the NFL will look more like the league did in 2019 than it did in 2020. The biggest change (as far as the game day experience is concerned) is the return of full stadiums, as fans will be permitted to attend games without size limits. 

That being said, there are a host of rules for players both vaccinated and unvaccinated. The new rules for the 2021 season include: 

  • Vaccinated players will be tested once a week, while unvaccinated players will undergo daily tests. Social distancing rules are in effect for unvaccinated players inside team facilities. 
  • Unvaccinated players who test positive are subject to at least a 10-day quarantine. Vaccinated players who test positive can return after two negative PCR tests taken at least 24 hours apart and if they are asymptomatic for 48 hours. 
  • Teams will have to forfeit games (resulting in a loss) if they are canceled before of a COVID-19 outbreak amongst unvaccinated players, and neither team's players will be paid. 

According to the NFL's research, 0.3% of vaccinated players tested positive for COVID-19 from August 1-21. That jumped to 2.2% for unvaccinated players, via Yahoo Sports

"We know that vaccines are working," NFL chief medical officer Dr. Allen Sills recently said, via "What we are seeing are some vaccinated people who test positive. But their illness tends to be very short and very mild, and that's exactly what the vaccines were designed to do. Let's all remember the vaccines were designed to prevent serious illness, hospitalization and death. They're doing a terrific job of that so far, not only in the NFL where we haven't seen any serious cases but in society as a whole."

Brady, Gronk and the gang are back. Are the Bucs ready to hoist the Lombardi Trophy again? Download the CBS Sports app and get the latest news, insights, and surprising predictions from our team of experts. Favorite the Bucs now if you've already downloaded the CBS Sports app so you don't miss a thing.