Restrictions will apply until at least Monday and limit household guests to 20, make masks compulsory in indoor public venues and on public transport, and restrict aged care visitation to two people.
It comes after it emerged this afternoon that the wife of the first Covid-19 community case - a man in his 50s - had contracted the virus too.
The man from Sydney's eastern suburbs had not been overseas recently, and did not work in a hotel quarantine, border or health role, setting off alarms on how he contracted the virus in the community.
"Within two weeks, we'll know if the virus' spread is growing or not," said Professor Raina MacIntyre, an expert in global biosecurity and infectious disease from the University of NSW.
"It is worrying because it's unknown where this man acquired this infection. Who did they get infected from? That's the real question of interest."
MacIntyre believes the man's infection will probably be traced back to hotel quarantine, but wonders how many people would have contracted the virus to link the two.
NSW Health confirmed yesterday that the man has a higher viral load.
"That's really concerning," MacIntyre said.
"This person looks like he's shedding a high amount of virus."
The man travelled to shops throughout eastern, central and western Sydney over a three-day period.