The NFL has 119 officials, enough needed to fill 17 crews. The league has no swing officials to use as substitutes.
So what happens when (not if) one or more officials test positive for COVID-19?
In a non-bye week, the crew that is off can fill open spots. An official also could pull double duty, working a Thursday game and either a Sunday or Monday game in the same week.
The league will have more options on a bye week.
But the NFL is not leaving anything to chance, training its officials on how a five-person crew would work in a pinch, Football Zebras reports. Officials are holding their annual clinic remotely, and among the training topics is the redistribution of responsibilities with less than a full crew.
Shortages in many states have reduced some high school officiating crews to five, or even four, officials, according to Football Zebras.
The league used officiating crews of five people between 1947-64 before the line judge was added in response to scrambling quarterbacks, per Football Zebras. The NFL added a side judge in 1978.
In addition to preparing for a reduced crew, the NFL also is addressing other measures to try to prevent the spread of COVID-19, including the use of facial masks and electronic whistles by officials and regionally assigning replay officials to limit travel.