Northampton Saints’ derby against Leicester Tigers has become the latest victim of Covid-19 outbreaks in English rugby union.
The fixture, which was due to take place on Saturday, is the fifth since Christmas to be cancelled in such circumstances.
Northampton said they had reluctantly agreed to cancel the match after “a number of positive tests” at the club.
Champions Exeter, meanwhile, still expect to play Bristol at the weekend despite some Chiefs players testing positive.
Premiership Rugby bosses say they will publish new protocols for match days and training to curb infections.
“We are incredibly disappointed and frustrated that we are unable to proceed with such an important fixture for the club,” said Northampton director of rugby Chris Boyd.
“The East Midlands Derby is a day that Saints supporters will have circled in their calendar months in advance. It’s a game entrenched in history and one our players particularly relish being a part of.”
A Premiership Rugby panel decides how to allocate points depending on the circumstances of each cancellation.
Typically, the team that has had to pull out gets two points and a defeat while their opponents get four and a win.
Saints believed they had enough players despite outbreak
Northampton said they had hoped to avoid a second consecutive cancelled fixture, after London Irish were forced to call off last Sunday’s match.
“The club has been absolutely rigorous in how we have followed the protocols laid out for us,” added Boyd.
“Despite returning a number of positive tests this week, we were confident that we have more than enough of our squad still healthy and available to play the game if required.
“However, we are following the advice we have been given, which was not to play the game and to close our training facility until next week.
“While this is a bitter pill to swallow, the health and safety of the players, staff and families of everyone at both Saints and Tigers is of course paramount.”
Exeter director of rugby Rob Baxter said they planned further testing to make sure no infectious players faced Bristol.
“We’re one of those clubs that do feel a responsibility to try and get on top of anything very, very quickly and certainly not risk players going onto the field against opposition,” he said.
The government has allowed elite sport to continue during a third national lockdown prompted a by a surge in cases.