Cardiff City’s Championship home match with Coventry City and two League Two games on 26 December have been called off because of positive Covid-19 cases.
Cardiff, who also had to postpone Saturday’s game with Derby, have “several cases of Covid-19 within the playing squad and staff”.
Northampton Town have also had to call off their home game against Walsall.
Forest Green also informed the EFL that they cannot play their game at Newport, their third straight postponement.
These are the first three games affected in the traditional Boxing Day programme.
More fixtures are likely to be postponed around the country as national figures rise following the effect of the Omicron variant, with daily lateral flow testing now taking place at clubs for all first-team players and staff.
Northampton’s club statement said: “In light of the increased transmission rate of the Omicron variant, the EFL will now review the circumstances surrounding the postponement.
“In addition it will assist affected clubs throughout this challenging period to help them mitigate against the risk of infection amongst players and staff, while ensuring their obligations to the EFL regulations are maintained.”
Newport’s club statement said: “Our Boxing Day fixture at home to Forest Green Rovers is postponed. Forest Green informed the EFL that it would be unable to fulfil the fixture at Rodney Parade due to a number of positive Covid-19 cases in their squad.”