What you need to know about COVID-19 today, Monday January 4.

NSW records zero locally acquired cases. 

NSW has recorded no new locally acquired coronavirus cases over a designated 24-hour period for the first time in almost three weeks.

In the 24 hours to 8pm Sunday, the state recorded only seven new cases in returned overseas travellers in hotel quarantine.

However, two new local cases were recorded after that 24-hour period ended, which will be included in tomorrow's official update. The cases are connected to the Berala BWS case, Acting Premier John Barilaro said on Monday.

NSW recorded no locally acquired cases of coronavirus overnight. Image: Getty. 

Despite the better news, Mr Barilaro said testing numbers were still "far too low" and implored residents in western Sydney to attend clinics if they have the slightest of symptoms, even if they have been tested previously.

Some 22,275 people were tested in the 24-hour period ended Sunday night, up slightly from 18,923 the previous day.

The government wants to see about 30,000 or 40,000 tests a day.

Sydney wedding breaches restrictions with 600 to 700 guests. 

Sydney Police are investigating a significant breach of coronavirus restrictions in Sydney's southwest, after 600 to 700 guests attended a wedding over the weekend. The attendance numbers are double the venue's COVID-safe capacity of 350 and the operator has consequently been fined $5,000. 

Guests at the wedding are yet to be penalised.

NSW Police Minister David Elliott told 2GB on Monday morning that the Fairfield wedding was a “blatant breach of the [health] order”.

“It has infuriated me,” Elliot told 2GB. “It’s not the way that I wanted to spend my Monday morning, I can assure you.”

“It’s only going to take one person to do the wrong thing, and then we have another Avalon on our hands.”

At the Monday press conference, Elliott also said: "This isn't one or two people coming from an area in lockdown or, you know, this isn't a dozen people that turned up unannounced, this is twice the amount of people that were allowed to attend that wedding reception in an area not far from Berala."

Mandatory mask rules in Sydney enforced from today.

Masks are now mandatory in some indoor settings in Greater Sydney. Image: Getty. 

Sydneysiders who flout new mandatory mask rules from Monday risk a $200 fine as the public health order comes into effect.

But Health Minister Brad Hazzard has asked NSW police to exercise discretion in handing out fines to those who ignore the new rules.

Masks are mandatory in shopping centres, on public transport, in places of worship, hair and beauty premises, entertainment venues such as cinemas and other indoor venues like post offices and banks. Hospitality workers are also required to wear one.

Mandatory masks have been introduced as a suburban bottle shop at the centre of a coronavirus cluster causes a headache for contact tracers.

Thousands isolating due to Black Rock cluster in Melbourne. 

In Victoria more than 2500 close primary and secondary contacts of those infected by the Black Rock cluster, in bayside Melbourne, are quarantining to avoid a major spread.

Victoria's border is now closed to all travellers from NSW, with some Victorian residents unable to make it home.

More than 1500 people have applied for exemptions to the strict border ban, but so far just 117 have been granted, including for end-of-life visits and funerals.

The Black Rock Cluster has now grown to 21 cases. 

New restrictions for Queensland returnees from Victoria. 

Anyone who has travelled to Victoria, which has a new coronavirus cluster, in the past two weeks has been banned from visiting Queensland's aged care facilities and hospitals.

The new restriction came into force from 1am on Monday and also applies to people wanting to visit other vulnerable facilities such as disability accommodation and prisons.

"We're responding quickly to protect people in these facilities by restricting any visitors who have been in high-risk locations so we can keep them as safe as possible," Chief Health Officer Jeannette Young said on Sunday.

Visitors from Victoria in Queensland are also being asked to get tested for coronavirus and self-isolate until they get their test results.

Queensland recorded zero new coronavirus cases on Sunday, and the state has so far racked up 110 days without a case of community-based infection.

There are 13 active cases in Queensland, all from hotel quarantine. 

Tens of thousands of people asked to isolate over BWS in Berala.

Queues for COVID-19 testing across Sydney have emerged in light of the latest outbreak. Image: Getty. 

Tens of thousands of Sydneysiders have been asked to isolate for 14 days due to "major concerns" over the transmission of COVID-19 during brief interactions at a western suburbs bottle shop. 

BWS in Berala was an exposure site for up to nine hours a day every day between December 22 and New Year's Eve, skipping only Christmas Day.

Most who dropped by the bottle shop across the Christmas period are now considered close contacts and need to isolate for 14 days even if they only attended the outlet for a short time.

More than 1000 people attended on Christmas Eve alone.

The COVID-19 cluster in Berala is up to 13 cases, with genetic sequencing revealing the source is a patient transfer worker who took a family of returned overseas travellers to a health facility.

The worker became infected and passed the virus to a colleague, who attended the Berala bottle shop for a "very fleeting amount of time" on December 20.

Acting Premier John Barilaro said on Monday the government had no qualms about tightening restrictions around Berala if unsourced COVID-19 cases began to emerge.

He admitted contact tracing at the BWS was a colossal task, as QR codes are not mandatory at NSW bottle shops.

- With AAP. 

Feature image: Getty. 

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