Brentford said in a statement https://www.brentfordfc.com/news/2021/january/brentford-fc-statement--next-two-fixtures-suspended they returned positive results on Monday and were advised by the league's medical team to close their training ground to carry further rounds of testing. Brentford's postponed games include Wednesday's home tie against Bristol City and a trip to Reading on Saturday. "The club (Brentford) informed the EFL that they would be unable to fulfil the fixtures following recent positive COVID-19 tests and the requirement for players and staff to self-isolate as per EFL and government guidance in order to mitigate against the risk of further infection," the EFL said in a statement https://twitter.com/EFL_Comms/status/1348955384032108550.
Bees’ next two outings in the division have been suspended after a series of Covid cases at the club
Brentford's next two Championship games have been postponed following a significant coronavirus outbreak at the club. Bees manager Thomas Frank last week returned a positive test and now another round of testing has confirmed further cases within the camp. The training ground has now been closed at the advice of the Football League while Wednesday's game against Bristol City and Saturday's trip to Reading have both been postponed and will be rearranged for a later date.
Brentford and QPR’s matches in the Championship on Saturday have been postponed because of Covid-19 outbreaks at their opponents. QPR’s trip to Luton has been called off after several positive coronavirus tests among Luton players and staff, while Brentford’s fixture at Bristol City is off because several Bristol City players have displayed coronavirus symptoms. Several Bristol City players displayed Covid symptoms on Friday.