The Blues were hit by a series of positive tests before their 0-0 drew at Wolves on Sunday and had a request to postpone the match rejected by the Premier League.
Thomas Tuchel claimed the safety of his players is being put at risk and Chelsea must now prepare for three games in eight days with a heavily depleted squad.
Lewis Baker, Josh Brooking, Bryan Fiabema Alfie Gilchrist, Joe Haigh, Lewis Hall, Xavier Mbuyamba, Dion Rankine, Teddy Sharman-Lowe, Xavier Simons, Harvey Vale and Jay Wareham are all thought to have trained with the first team this week.
Chelsea had just four outfield players on the bench for their game against Wolves.
Romelu Lukaku, Callum Hudson-Odoi and Timo Werner tested positive for Covid last week, and Chelsea asked for the fixture to be called off on Sunday morning after more players went into isolation.
They were also without Trevoh Chalobah and Hakim Ziyech due to injury.
After the Brentford game, Chelsea are due to face Aston Villa on Boxing Day and then Brighton on December 29.
