Three Championship games on 26 December and 10 more in the EFL have been called off because of Covid-19 cases.
Cardiff City v Coventry City, Stoke City-Barnsley and Peterborough-Reading have been postponed in the second tier.
Four games in League One and six in League Two have also been called off.
The English Football League says "there is optimism that disruption can be minimised" and confirmed that league, Carabao Cup and Papa John's Trophy ties can continue "where safe to do so".
League Two leaders Forest Green, who have now suffered three successive postponements, head the list of six games called off so far in the fourth tier.