The two were at practice Thursday along with QB Cam Newton, meaning the Patriots are nearing full strength after their run-in with the virus.
Gilmore, 29, was taken with the No. 10 overall pick by the Bills back in 2012. He played out his rookie contract, but the Bills elected to pick up his fifth-year option for the 2016 season.
Gilmore would later depart for a five-year, $65 million contract that includes $31 million guaranteed with the Patriots. He made a base salary of $9.5 million for the 2019 season.
In 2020, Gilmore has appeared in four games for the Patriots and recorded 11 tackles, one interception, a forced fumble and two pass defenses.