English Premiership rugby is to ban players from taking ice baths and engaging in face-to-face try celebrations in a bid to restrict the spread of the coronavirus.
Several league matches this season have already fallen victim to Covid-19, prompting officials to introduce additional precautions.
Among the measures announced Wednesday by the Professional Game Board - which includes representatives of Premiership Rugby, the Rugby Football Union and Rugby Players' Association - ahead of this week's Premiership games are a ban on ice baths and face-to face try celebrations.
Meanwhile the use of changing rooms will be limited to showering after outdoor training sessions.
A review of schedules must be undertaken by clubs in order to reduce the amount of time spent by players at training facilities.
The measures will, a statement said, "provide additional mitigation against Covid transmission among elite players".
Earlier on Wednesday, Northampton's weekend match against Leicester was cancelled after the Saints returned positive coronavirus test
The club's training ground has also been closed, Premiership Rugby said in a statement.
"The health and safety of players, management, staff and match officials is our priority," said a Premiership Rugby spokesman.
"We wish those who have tested positive at Saints a speedy and safe recovery."
Under Premiership Rugby regulations, a panel will determine the allocation of points. Leicester can realistically expect to be awarded four points and Northampton two, with a 0-0 scoreline declared.
It is the fifth Premiership game to be cancelled in such circumstances this season.
Northampton's away match against London Irish last weekend was scrapped because of positive tests in the Exiles' camp.
In a statement, Northampton 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 Monday, January 11."
Northampton rugby director Chris Boyd said: "We are incredibly disappointed and frustrated that we are unable to proceed with such an important fixture for the club."
Champions Exeter also revealed "some" positive Covid-19 tests in camp, but their clash with Bristol is still scheduled to go ahead.
Chiefs director of rugby Rob Baxter said there had been "a slight impact on the availability of players but not huge".