Four cases of coronavirus from the Omicron variant have been confirmed in NSW after the discovery of two more infected people.
Almost 150 people have arrived in NSW from southern African countries where the new Omicron COVID-19 variant is running rampant, with four cases now confirmed.
The two new cases arrived on a Singapore Airlines flight from southern Africa on Sunday, and every other person who was on that flight is now a close contact who needs to get tested and isolate for 14 days immediately.
Both of the newly confirmed cases are fully vaccinated and are now in special health accommodation.
Genomic testing on Sunday confirmed two overseas travellers who arrived in Sydney had been infected with the new coronavirus variant.
Both passengers were asymptomatic when they arrived on Saturday night and are in isolation in the Special Health Accommodation. Both are fully vaccinated.
NSW Premier Dominic Perrottet said 141 people have come to the state from the nine countries of concern over the past 24 hours, and all have been sent to hotel quarantine for 14 days.
Although he has ordered all international arrivals to quarantine at home for 72 hours, Mr Perrottet insisted the NSW international and state borders would remain open.
The three-day quarantine order is on top of a federal government requirement for travellers to enter quarantine for two weeks if they have been in South Africa, Lesotho, Botswana, Zimbabwe, Mozambique, Namibia, Eswatini, Malawi or the Seychelles in the past 14 days.
"Ultimately we need to open up to the world (and) we need to do so safely," he told reporters on Monday.
"We don't need to have a knee-jerk reaction, we need to have a proportionate and balanced response to the situation that's in front of us."
"The responses should not be 'Let's shut down'."
Mr Perrottet also stressed NSW was better equipped to confront new variants.
"We've got to learn to live alongside the variants of the virus that come our way," he said.
"And the vaccination rate here is one of the highest in the world.
"That is not the case in the southern African nations."
The premier has said there are no plans to adjust the state's reopening roadmap, which has restrictions easing for the unvaccinated on December 15.
However, restrictions will be tailored in response to the variant if needed, he said.
Meanwhile, the state added 150 new infections to its caseload on Monday.
For the fifth consecutive day, no new deaths were reported.
Hospitals are treating 170 patients, five more than the previous day, including 25 people in intensive care. Ten require ventilation.
NSW is 94.5 per cent single-dosed for everyone 16 and over, while 92.4 per cent are fully vaccinated.
Of 12- to 15-year-olds, 81.3 per cent have received one jab and 76.5 per cent both.
Australian Associated Press
Sign up for our newsletter to stay up to date.