Parts of NSW will return to mandatory mask-wearing and restrictions on private gatherings after a second community case of coronavirus was confirmed on Thursday.

The wife of the man from Sydney’s eastern suburbs who tested positive on Wednesday, sparking the fresh alarm, was also diagnosed with COVID on Thursday.

It came as state health authorities said genomic testing had linked both infections to a returned traveller from the US in hotel quarantine in Sydney.

NSW Premier Gladys Berejiklian said “precautionary measures” would return across the greater Sydney, Illawarra and central coast areas from 5pm Thursday.

“We know that the incubation period of this virus is 14 days and everybody has to be on high alert moving forward, especially over the
next few days,” she said.

The restrictions will last until at least midnight Monday. They include:

• Limiting gatherings in private homes to no more than 20 people;
• Mandatory masks in indoor settings such as public transport and supermarkets. This rule also applies to retail and hospitality staff;
• No singing or dancing in indoor venues, including places of worship and entertainment venues (weddings excepted).
• Drinkers at indoor bars must be seated.

“We believe this is a proportionate response to the risk ahead of us,” Ms Berejiklian said.

However, she acknowledged the limits on private gatherings would be difficult for some, with Mother’s Day on Sunday.

“We know that transmission in the family home is a high risk,” she said.

“I appreciate that it’s Mother’s Day but we also appreciate that 20 people within the home is manageable for people to celebrate that important day.”

Tweet from @NSWHealth

Chief health officer Kerry Chant said 10 close contacts from the infected man had returned negative tests – the other is his wife, who also has the virus.

She first returned a test with a “very, very high CT value” and her level of infectiousness increased in a second test. Authorities think they have caught her early in her infection cycle.

Dr Chant said health authorities were trying to trace the links between the infected returned traveller – who arrived in Australia on April 26 and tested positive to the virus on their first day – and this week’s two Sydney cases.

“There is a missing link, someone that, because there is no direct contact that we’ve been able to establish yet,” she said.

“What we’re concerned about is there is another person that is, as yet, unidentified that infected our case, and then the hypothesis is that our case passed it on to the household.”

She identified three venues of concern that predate the first community infection, but said authorities were using to try to trace the spread of the virus. They are:

• Fratelli Fresh, Westfield Sydney, and F5 Pitt Street, 1.15-2.15pm, Tuesday, April 27;
• Bondi Trattoria, 34 Campbell Parade, Bondi Beach, 12.45-1.30pm, Thursday, April 29;
• See the latest NSW Health venues of concern here

Earlier, NSW Treasurer Dominic Perrottet confirmed he was in isolation after being identified as a close contact of the Sydney man diagnosed on Wednesday.

Mr Perrottet was at the District Brasserie, in Sydney’s CBD, on April 30, at the same time as the man in his 50s.

Mr Perrottet said on Thursday his coronavirus test had come back negative, but he would keep isolating for 14 days from April 30, in line with NSW Health requirements.

Sydney Roosters players have also been sent for virus tests and staff told to stay home after the infected man visited the Azure Cafe on Monday, less than 100 metres from the NRL club’s Moore Park headquarters.

Players were rushed in for tests on Thursday, ahead of Friday night’s match against Parramatta.

The main concern centres around the infected man’s visit to the Azure Cafe on Monday, less than 100 metres from the Roosters’ headquarters.

The cafe is a popular coffee stop and lunch venue for both Roosters and Sydney Swans AFL players, as well as sports officials.

Tweet from @sydneyswans

It’s believed, however, that no Roosters were in the cafe at the time of the infected man.