The right-back is still sidelined with the illness that ruled him out of the 2-2 draw at Aston Villa on Saturday.
Diogo Dalot played at Villa Park and will be a strong contender to feature against the Bees in our first visit to the Brentford Community Stadium tonight (Wednesday).
West Ham visit Old Trafford on Saturday, in a 15:00 GMT kick-off, before a break in fixtures due to the international calendar.
It means we may not see Wan-Bissaka back in the squad until the Emirates FA Cup fourth-round tie at home to Middlesbrough on Friday 4 February.