The NFL's chief medical officer says asymptomatic players are not spreading COVID-19 based on his observations during this season.

Dr. Allen Sills appeared on the NFL Network on Thursday and said the league hasn't "seen this phenomenon that people have discussed, which is asymptomatic people in the facility spreading the virus to others."

Sills told ESPN later Thursday: "We've got our hands full with symptomatic people."

"Can I tell you tonight that there has never been a case when someone without symptoms passed it on to someone else? No, of course I can't say that," he told ESPN. "But what I can say to you is that I think it's a very, very tiny fraction of the overall problem, if it exists at all."


He also said to ESPN that "asymptomatic transmission inside our facilities just didn’t fit with what we were seeing."

He told the NFL Network that the key is "symptom recognition and prompt testing."

"As we’ve gone back and looked throughout the entire season, what we’ve seen consistently is that when people have symptoms, that’s when they seem to be contagious to others," he said. "And that’s why we’re asking people to come forward and acknowledge symptoms because that’s the point at which they’re vulnerable and the point at which they expose themselves to others."

Last weekend, the NFL agreed with the NFL Players Association to scale back testing for vaccinated players. The move aligned with guidance from the Centers for Disease Control and Prevention, which recommends "diagnostic testing" only for symptomatic or close-contact vaccinated people and "screening tests" only for unvaccinated people.

The NFL previously required vaccinated players to get tested weekly before amending the protocols. The NFLPA had advocated for daily testing for vaccinated players but eventually agreed to "target" testing.

The league has seen COVID-19 spike over the past couple of weeks, and Cleveland Browns center JC Tretter, the players' union president who has been pushing the league for daily COVID-19 testing all season, tested positive for the virus Thursday.