NFL chief medical officer says 'symptomatic' players are responsible for COVID-19 spread

But in a very interesting interview with NFL Network, chief medical officer Allen Sills revealed the current spread of COVID in the league is being driven by individuals who do have symptoms -- not the other way around. 

"Clearly if you want to look at the overall pattern and concern about transmission, it is not being driven by people who have no idea that they are infected and they are infecting scores of others. This is being driven by people with symptoms and the exposures during that symptomatic period," Sills detailed in a follow-up interview with ESPN.

Sill's findings come not long after the NFL altered its testing policy, fine-tuning it to focus more on players and personnel with symptoms whether they are vaccinated or not. (Unvaccinated players still have to be tested daily.) The new methods have caused some to question whether asymptomatic, vaccinated personnel are spreading the virus but going undetected.

"Asymptomatic transmission inside our facilities just didn't fit with what we were seeing," Sills said.

He further explained: "Once it replicates enough to cause you to have symptoms... now there's enough there for us to say that you're going to be shedding it out in a live form to infect someone else. It's really a matter of degree of how strongly we think you may be infected. You have to get to a point where you're infected enough that you're beginning to shed active viral particles, and that usually correlates with the onset of symptoms."

One of Sill's main points was that players who had symptoms but initially tested negative appear to be the biggest offenders because they contribute their symptoms to something else go about their day.

"We were seeing people walk around for two or three days and expose others because they didn't speak up about their symptoms because they had gotten that negative test," he said. "So we're at our best when we're testing at the onset of symptoms."