The latest people to test positive for coronavirus in New South Wales are believed to have been together at a Christmas party, but authorities are desperately trying to determine how the unlinked cluster broke out.

An increase of 18 cases and the emergence of a new ‘Croydon cluster’ on Wednesday have again put the spotlight on whether NSW went hard enough when the first case was detected.

Health authorities are warning that all Australians need to stay vigilant in coming days as the virus may have spread to other parts of the country.

Already there are signs it has.

On Wednesday night, a spokesman for the Victorian government confirmed authorities believed three new cases in their state were linked to the Sydney cluster.

Lax quarantine administration at Sydney Airport with literally hundreds of exemptions a week combined with discredited “proportionate” /hotspot strategy now having consequences in Victoria. Time for @GladysB and NSW to clobber #Coronavirus and take effective steps now. @SParnis https://t.co/kj7A34Hht7

— Bill Bowtell AO (@billbowtell) December 30, 2020

What we know about the Victorian cases so far

The infection of the three women, two aged in their 40s and one in her 70s, brought to an end the state’s 61-day streak of no COVID-19 cases.

The women, from Mitcham, Hallam and Mentone, are isolating at home – as are their close contacts – and have provided details of the sites they had visited in recent days.

High-risk sites:

• Mentone/Parkdale Beach on 27 December
• Century City Walk and Mocha Jo’s, Glen Waverley on 28 December
• Katialo restaurant, Eaton Mall, Oakleigh on 28 December.

Other possible exposure sites, and times, include:

• Fountain Gate Shopping Centre shops including Kmart, Big W, Target, Millers, King of Gifts, Lacoste on 26 December
• Holy Family Parish Doveton Catholic on 26 December
• Check the Department of Health and Human Services website for a full list, including possible times of infection.

Victoria’s Commander of COVID-19 response Jeroen Weimar said his state was deploying its “full outbreak approach” to track the cases and contain the spread.

“We are so thankful that these people did the right thing and got tested. We always knew this virus had us in a precarious position and we need to make sure we do everything we can to stamp out any further transmissions,” Mr Weimar said.

“Now more than ever people should not let down their guard. Maintain physical distancing, practise good hand hygiene. Stay at home if you’re unwell and, most of all, get tested if you have any symptoms at all.”

Victoria is expected to release further details about the cases, and possible sites of transmission, on Thursday.

What we know about the new NSW cluster

NSW chief medical officer Kerry Chant said the family, all living in the suburb of Croydon, gathered several times over the Christmas period – when authorities suspect the virus was transmitted.

“As you understand, close families often get together at this time of year with multiple other members of families on multiple days,” Dr Chant said.

She said 34 close contacts of the family members had been identified and authorities were bracing for an increase of connected cases.

On Wednesday NSW Premier Gladys Berejiklian announced changes to NYE restrictions. Photo: AAP

Concerns NSW did not go hard enough

Deakin University chair of epidemiology Catherine Bennett said she did not want to be “inflammatory” but the number of unknown cases, including the Croydon cluster and two in Wollongong, had become “alarming”.

“That’s telling you they haven’t got the complete handle on it,” Professor Bennett told The New Daily. 

Professor Bennett said the numbers would bounce around in coming days as some people only experience symptoms late in the incubation period, but hopefully, NSW Health had isolated those new cases.

“We have to be mindful we’ll see waves (of case numbers), but what we’re looking for is how many of those are in quarantine already, and what they learn about the Wollongong cases and the Croydon cluster,” she said.

“Hopefully, they find those links.”

Professor Bennett said NSW had handled the situation well and did not need a city-wide lockdown, but warned it would not take much for the outbreak to get out of hand.

“Does it mean lockdown? No. But do you need to think about masks and numbers in venues? Well, all of those things need to become much more the table,” she said.

Dr Catherine Bennett said the country needed to remain vigilant.

“It’s about trying to manage that risk, and supporting what the health department is doing, to avoid a major lockdown in January.”

Indoor gathering limits have effectively been halved for New Year’s Eve, with Greater Sydney, Central Coast, Wollongong, Nepean and Blue Mountains areas all capped at five.

Outdoor gatherings have been capped at 30 for those areas.

The Northern Beaches hot spot has been sliced in two and has a five-person limit for indoor gatherings and a five and 10 outdoor limit for the southern and northern zones respectively.

The next potential day for a super spreading event is Thursday when people will gather for NYE parties.

What happens then, will be critical for the state, Professor Bennett said.

“One incubation period from Christmas is New Year,” she said.

“So we could have a few people becoming infectious, who were exposed over Christmas who then take it to different households. That could mean by the second week of January you’re seeing this take off.”

To help keep the cluster contained, Sydneysiders needed to get tested if they have symptoms and wear masks, she said.

“Masks are one way of helping avoid other restrictions.”

Warning for other states

Until the incubation period had lapsed the whole country needed to be alert (but not alarmed) as it is possible COVID-19 has spread out of Sydney and into other states, Professor Bennett said.

“The virus is in the community and we don’t know every case,” she said.

“The risk is demonstrably higher than understood a week ago and that is true Australia wide.

“We don’t know where everyone from Sydney might have been. We put restrictions on people coming back into Melbourne, but it could have come in earlier.”

Victorians stuck

On Wednesday night, Victoria confirmed new border restrictions would be in place at 11.59pm on Thursday.

Victorians who have been in the Blue Mountains or Wollongong, and who want to return home, must do so before that time or face restrictions such as mandatory home quarantine.

Update: New border restrictions will come into effect from 11:59pm 31 December.

If you have visited the Blue Mountains or Wollongong regions from 27 December, you have until then to return to Victoria.

Thread ⤵️ pic.twitter.com/GFAMN380ku

— Victorian Department of Health (@VicGovDH) December 30, 2020

Victorians who have found themselves stuck in Sydney after not being able to leave before the border shut are frustrated the state government has no way home for them.

When the Victorian government announced residents had eight hours to get home or face hotel quarantine Nikita McHugh decided to stay.

With no way home, Nikita McHugh is stuck in lockdown in Sydney.

Nikita hadn’t seen their parents in almost six months and did not want to spend Christmas isolated – but since hotel quarantine has been taken off the table, they have no way of getting home.

“I have no problem doing 14 days’ hotel quarantine to protect the state, but we aren’t given that option,” Nikita said.

“We weren’t given any warning we would be shut out.”

The lack of options to get home had left Nikita and their brother in “limbo”.

“I live in Victoria. I have a life there. I’m having to stay here indefinitely. Every other state is offering hotel quarantine, so do they not trust their system still?”

On Wednesday, Victoria’s Police Minister Lisa Neville said decisions about the border were being reviewed daily but no one was ready to open up.

“We’re still a long way from that border being open,” she said.

“I know we were concerned about the Wollongong spread and the case there, and that occurred I think through churches, so we’ll continue to monitor this and if we need we’ll extend that red zone,” she said.