Northampton's Premiership rugby clash against Leicester on Saturday has been cancelled after several Saints players returned positive results for the coronavirus.
Premiership Rugby said the Saints' training ground had also been closed.
"The health and safety of players, management, staff and match officials is our priority," a Premiership Rugby spokesperson said.
"We wish those who have tested positive at Saints a speedy and safe recovery."
Under Premiership Rugby regulations, a panel will now be convened to determine the allocation of points, but Leicester can realistically expect to be awarded four points and Saints two, with a 0-0 scoreline declared.
In a statement, the Saints said: "In this week's round of PCR testing ahead of the east midlands derby, the club returned a number of positive tests and had further players unavailable for selection following the contact tracing process.
"In close consultation with Public Health England, the match has subsequently been called off and Saints' training also cancelled until the next round of testing - scheduled for January 11.
"The players involved have already begun a 10-day isolation period."
It is the fifth Premiership game to be cancelled in such circumstances this season.