The lab used by the NFL for COVID-19 tests said Monday that an isolated contamination caused 77 “most likely false positive results.”

In a statement, BioReference Laboratories said the test results on Saturday were contaminated during preparation at its lab in New Jersey. Eleven clubs were affected, and the tests were reexamined and found to be false positives.

“The NFL immediately took necessary actions to ensure the safety of the players and personnel,” said Dr. Jon R. Cohen, executive chairman of BioReference, which does all COVID-19 testing for the 32 NFL teams in five labs across the country. "Re-agents, analyzers and staff were all ruled out as possible causes and subsequent testing has indicated that the issue has been resolved. All individuals impacted have been confirmed negative and informed.”

Among teams reporting false positives, the Minnesota Vikings said they had 12, the New York Jets 10 and the Chicago Bears nine. The entire episode puts the NFL and its testing procedures through BioReference in a precarious position with the opening game kicking off on Sept. 10.

There are five labs nationwide that service the 32 teams, with only the New Jersey facility having the false positives this weekend. Anyone testing positive for COVID-19 — even a false positive upon a retest — is required to have two more negative tests before being cleared to return.

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The New York Giants said Monday that two staff members whose test results initially came back as false positives were back at work. Both were given a point of care test Sunday morning, the results of which were known within the hour, and were administered the standard test they undergo on a daily basis, the results of which were known Sunday night. Both results were negative.

Two other Giants staffers were deemed through contact tracing to have been in close contact for more than 15 minutes with their peers who had the false positives. They also returned to work Monday.

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