The Sept. 10 contest between the Kansas City Chiefs and the Houston Texans had fans in the stands — 15,895 of them — but far fewer than the number Arrowhead Stadium can hold, 76,000.
"I want to remind everyone that Covid-19 is anywhere and everywhere," Kansas City Health Department Director Dr. Rex Archer said in a statement. "While we’re all tired of it, frustrated and even angry at how it has altered and stricken our lives and livelihoods, we must continue to think of those who have not and will not survive it."
NFL games this season have had a drastically different look because of Covid-19, a disease that has killed more than 198,600 people in the United States, according to NBC News' count.
The Chiefs have announced a number of steps to help prevent the spread, including a mask requirement, changes to concessions and rules about social distancing.
The team said that the person who tested positive last week and their group was in the lower level of the stadium and that its policies kept the potential exposure low.
The infected person and their group were wearing masks when they entered the stadium, the team said.
"By design, the stadium's COVID protocol plan limited potential exposure to a single seating zone within the stadium," the Chiefs said in a statement Thursday.
The city's health department said the Chiefs responded quickly, which helped everyone who may have been exposed to be quickly identified.
The Chiefs said in Thursday's statement that its contact tracing mechanisms, like scanned data from parking and tickets, allowed the team to identify those who the person sat with, where they entered and any staff the person interacted with.
The statement suggested that whether its plan to have some fans in the stands will work depends in part on those going to the games.
"Compliance with the protocols remains a key component to making this plan effective," the Chiefs said.
Not all NFL teams are allowing fans at games this season, although some have set a date for when they expect to do so, according to NBC Sports.
More than 108,900 cases of Covid-19 have been confirmed in Missouri, with more than 1,800 deaths, according to NBC News count.