United’s Premier League clash with Brentford on Tuesday is in doubt after multiple positive cases were detected among players and staff on Sunday morning, the BBC reported.
All the players involved had tested negative ahead of Saturday’s 1-0 win at Norwich.
Training was switched to non-contact, individual drills outside to prevent further spread of the virus.
Villa chose to cancel their training session on Sunday due to a number of positive cases, according to The Athletic.
Only one Villa player is believed to be positive with more cases among training ground staff.
Tottenham’s trip to Brighton, scheduled to take place on Sunday, was postponed earlier in the week after an outbreak in the Spurs camp affecting 13 players or staff.
Spurs also face being eliminated from the Europa Conference League after a date could not agreed to replay their final group game against Rennes.
Leicester have also been affected with seven players missing for their 4-0 thrashing of Newcastle on Sunday.
Arsenal manager Mikel Arteta has called for clarity over how many positive cases are required for a match to be postponed.
The Gunners’ season opener at Brentford in August went ahead despite four cases among Arteta’s squad.
Premier League sides were told to return to emergency protocols this week to limit the spread of the virus amid fears over the potential impact of the surging Omicron variant on the English top flight.
From Wednesday, supporters will have to provide proof of vaccination or a negative test result to enter stadiums with more than a 10,000 capacity in England as part of a range of measures designed to slow the spread of Omicron.
Nearly the full 2020/2021 Premier League season was played behind closed doors due to coronavirus restrictions.
However, English clubs have been able to host capacity crowds since the start of the current campaign.