Week 4 will be remembered as the first time Covid-19 made a heavy impact on the 2020 NFL season.

Most of the week’s attention was directed at Tennessee — news came out each day beginning Monday of more Titans positive tests. That led to the postponement of the Titans vs. Steelers game to Week 7. Late in the week, Cam Newton’s positive test threw New England’s game at Kansas City into doubt. And a false positive on the New Orleans Saints threatened to affect their game against the Detroit Lions.

This is a timeline of each day’s new COVID-19 developments during Week 4.

MORE: Explaining the NFL’s COVID-19 rules

Sept. 24: First Titans positive test

Tennessee defensive back Greg Mabin tested positive for COVID-19 on Sept. 24. Titans head coach Mike Vrabel said Mabin was removed immediately from the facility upon the positive test outcome. 

Mabin had been signed on Sept. 21 to the Titans practice squad. During the pandemic, the NFL has instituted additional protocols for signing players that Mabin would have had to pass.

Sept. 26: Titans coach tests positive; Terrell to COVID-19/Reserve list

Tennessee outside linebackers coach Shane Bowen received a positive test result the Saturday before the Titans traveled to play at the Minnesota Vikings. The Titans have said they went through all the required league contact-tracing procedures after Bowen tested positive. 

Outside of Tennessee, the Atlanta Falcons placed rookie cornerback A.J. Terrell on the COVID-19/Reserve list. Terrell’s contact tracing didn’t return any concerns, so the Falcons and Bears played as scheduled in Week 3. No further Atlanta or Chicago players have been placed on the COVID-19/Reserve list since.

Sept. 27: Titans play at Vikings

With Bowen at home, Vrabel was the Titans’ defensive play-caller against Minnesota. As the week goes on, the Vikings will come under increased scrutiny due to playing Tennessee, but no Vikings have tested positive.

MORE: What happens when an NFL player tests positive for COVID-19?

Sept. 28: Two positive Titans tests

The first news comes out of positive tests with the Titans – one player and one personnel person. Vrabel also confirmed this Monday that Bowen had tested positive, that the Titans had followed protocol and that Bowen hadn’t been in Minnesota.

Sept. 29: Eight more Titans positives

Three more Titans players and five more personnel people received positive test results. This led to all in-person activities at the Tennessee facility to be shut down, along with the facility in Minnesota temporarily being shut down. The NFL did not yet make any decisions in regards to Tennessee’s Week 4 game, which was scheduled to be a home contest against the Steelers.

Three Titans players were placed on the COVID-19/Reserve list: DaQuan Jones, Beau Brinkley and Tommy Hudson. 

Sept. 30: Another positive Titan

The Titans placed linebacker Kamalei Correa on the COVID list. Vrabel told media that the Titans were preparing to play as early as Monday. Vrabel also told media that players needing treatment were allowed into the facility in masks, and he said some of the players who tested positive were experiencing flu-like symptoms.

In Minnesota, players were allowed back into the facility with increased health protocols.

Oct. 1: NFL postpones Titans-Steelers

The NFL announced it’d be postponing the Titans vs. Steelers game “to ensure the health and safety of players, coaches and game day personnel.” Titans cornerback Kristian Fulton was added to the COVID list.

Additionally, the NFL released a memo of increased protocols for teams that had been exposed to the coronavirus, which included two daily tests for everyone working with such a team.

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Oct. 2: NFL reschedules Titans-Steelers

Two more Titans, including receiver Adam Humphries, were added to the COVID list. The NFL also announced how it’d be shifting schedules to account for the Titans-Steelers postponement: The teams would play Week 7, with the Steelers and Ravens having their Week 7 game moved to Week 8.

That made Tennessee and Pittsburgh’s official bye Week 4, while Baltimore had its bye moved up a week to Week 7. The NFL also reiterated its fine structure for missing COVID tests – a $50,000 fine for one missed test and a one-game suspension for a second.

Oct. 3: Cam Newton tests positive

The positive tests expanded outside of Tennessee as news came out Saturday morning that Patriots quarterback Cam Newton had tested positive for COVID-19. The Titans also had another positive test – 2019 first-rounder Jeffery Simmons – and the Chiefs had one as well, in practice squad QB Jordan Ta’amu (whose Week 4 role was playing Newton on the K.C. scout team).

Adam Schefter’s initial report indicated the NFL would like to move the Patriots’ game in Kansas City to Tuesday.

Oct. 4: Saints receive false positive; Patriots-Chiefs rescheduled

Overnight into Week 4 Sunday, news came out that Saints fullback Michael Burton had received a positive COVID-19 test, which likely would’ve moved the New Orleans game against the Lions. But multiple reports came out Sunday morning that indicated Burton had a false positive and that the rest of the Saints had tested negative, so they played as scheduled against Detroit at 1 p.m. Sunday.

Just before games kicked off, the NFL announced how it’d shift the schedule for Patriots-Chiefs. Those teams would play Monday at 7:05 p.m. ET on CBS, while Monday Night Football would shift backward by 35 minutes to kick off at 8:50 p.m. ET between the Falcons and Packers on ESPN.