The Professional Game Board said more work needs to be done before Premiership rugby teams in England can start training.
A five-week break has been implemented in the Premiership, with the Champions Cup and Challenge Cup quarter-finals pushed back.
Bristol Bears continued their fine form with a comfortable victory over Harlequins, who beat Premiership leaders Exeter Chiefs last week.
There was no debut victory for Bath new boy Rhys Webb as Bristol Bears continued their charged at a packed Rec.
Exeter plundered eight tries in a crushing victory over Northampton as they took another step closer to finishing top of the Premiership.
Henry Purdy and Lewis Thiede touched down within two minutes of one another to see Bristol Bears past Northampton Saints.
Exeter Chiefs rallied in the second half against Sale Sharks, but the Premiership leaders still slipped to a first defeat since November.
Five tries in each half saw Premiership basement side Saracens make light work of thumping Worcester Warriors on Saturday.
Wasps claimed their second win of the Premiership season by overcoming Bristol.
Saracens won a fifth straight Premiership match, though they are still far behind Leicester Tigers, who were defeated by Exeter Chiefs.