Surrey's opening match in the divisional stage of the County Championship, against Durham at Chester-le-Street, has been cancelled following a positive Covid-19 test.
The unnamed member of Surrey's squad returned a positive result ahead of the Division Two match, which was due to start on Monday. In a statement, the ECB said a "significant number" of Surrey squad members had been deemed close contacts.
"The player has begun to self-isolate along with a significant number of the Surrey squad who have been identified as close contacts," the statement said.
"Due to the required isolation protocols and the extensive impact on Surrey's available playing squad, reluctantly the decision has been made that the match will not go ahead."
The board is due to make a decision on how points for the fixture will be awarded.
Covid-19 cases have had a significant impact on the summer, with Derbyshire's match against Essex at Derby abandoned after day one during the conference stage of the Championship. Derbyshire also saw two Blast matches called off because of a shortage of players, while Gloucestershire's Royal London Cup fixture against Middlesex at Radlett fell victim to an outbreak.
Earlier in July, Kent had to call up an entirely new squad on the eve of their match against Sussex, days after England were forced into a similar position by a number of Covid positives in their ODI playing group.
There were also a number of Covid-19 cases during the Hundred, although none resulted in games being cancelled.