Below is the NFL's wording on its rules for players returning from COVID-19 cases.
Following a positive test, if the player is asymptomatic, he can return once:
10 days have passed since the initial positive test; OR
Five days have passed since the initial positive test and the player receives two consecutive negative PCR virus tests at least 24 hours apart within that five-day period
Following a positive test, if the player demonstrates symptoms, he can return when:
At least 10 days have passed since symptoms first appeared; AND
At least 72 hours have passed since he last experienced symptoms
In either case, a player who tests positive must be cleared by his team's head physician before returning.
Additionally, all players who have tested positive and recovered (or who have tested positive for antibodies) will undergo additional cardiac screening.
Below are the NFL's protocols for cardiac screening:
Following a mild, symptomatic infection, a player must complete at least a three-day progressive exercise protocol under the supervision of the team medical staff with appropriate clinical monitoring.
Following a moderate to severe infection, a player must complete a progressive exercise protocol for a recommended seven days or for a period equal to twice the duration of the hospitalization.
The NFL also has implemented contact tracing. Conducted by a third party called IQVIA, the contact tracing is implemented after an infected player receives a positive test result in an effort to identify people who came in close contact with that person. Kinexon Proximity Recording player tracking devices are being used to identify in-game close contacts, and the devices must be worn during all team activities.
Teams have been instructed to notify health authorities of positive tests as required by applicable local regulations or laws.
In order to account for the possibility of false positive tests. Initial positive tests are followed by two more tests (a nasal swab and a point-of-care test). While those who initially test positive must still isolate while awaiting their backup test results, they can be cleared on the same day if both backup tests immediately come back negative.