Speaking to reporters about the situation, Allen said he was "super frustrated" about not being allowed to participate in practice because of the false positive:
“I got a call at six in the morning saying I tested positive and honestly, it's nothing you want to hear and I'm sitting there like, 'I feel fine, there's nothing wrong.' I come in, try to get in the building and I have to go through protocol. I went through the test that was right here that gives you results in 15 minutes and that came back negative. I'm super frustrated that I wasn't here yesterday."
Irregularities at the BioReference lab in New Jersey that the NFL uses to examine its COVID-19 tests returned 77 positive tests from 11 different teams Sunday.
Per ESPN's Adam Schefter, all of the tests came back negative after being rerun by the lab.
Dr. Jon Cohen, executive chairman of the BioReference lab, said in a statement released Monday that an investigation determined the false positives were likely "caused by an isolated contamination during test preparation in the New Jersey laboratory."
Per Sal Maiorana of the Rochester Democrat and Chronicle, Allen, Quinton Jefferson, Vernon Butler and Harrison Phillips all had to miss Buffalo's practice Sunday because of the false positives.
All four players were allowed back on the field Monday.
The Bills will open the regular season at home against the New York Jets on Sept. 13.