Two more coronavirus cases have been found in Sydney’s Northern Beaches, bringing to four the number diagnosed in the area in the past 48 hours.

Premier Gladys Berejiklian confirmed the latest infections on Thursday morning, where she again urged everyone in the area to turn out for virus testing.

“We want to get on top of this and don’t want this concerning us in the last few days before Christmas,” she said.

“We’re urging everyone to be as vigilant as ever.”

On Wednesday, NSW Health confirmed surprise virus infections in a Northern Beaches woman in her 60s and a man in his 70s. They are close contacts of each other.

The source of the pair’s infections is yet to be found. NSW Health is urgently undertaking genomic sequencing and contact tracing.

There are few details about the cases revealed on Thursday, except that one is in Frenchs Forest and the other from further north.

People reported waiting hours for testing at Mona Vale on Thursday. Photo: AAP

NSW Health issued a string of alerts for venues and shops in Avalon and Palm Beach after the first two positive cases said they had visited several places while infectious.

There were some media reports on Thursday that the pair failed to isolate after their virus tests. State Health Minister Brad Hazzard refused to be drawn on that.

“From time to time, people might not respond as quickly as on an objective medical basis that we would like them to but we have never commented on those particular cases, and we won’t, because we want to encourage people always to feel they can come forward,” he said.

NSW Health said everyone living in the Northern Beaches area should monitor for COVID symptoms and get tested immediately if they appeared.

• See a full list of the latest NSW Health venues of concern here

Ms Berejiklian said authorities would ban visitors from aged care facilities in the Northern Beaches “until we identify the source of infection and feel more confident we have it under control”.

On Thursday morning, there were long queues outside a COVID-19 testing clinic at Mona Vale Hospital, even before the additional two infections were confirmed.

One local woman said she was at the Avalon Woolworths at the same time as one of the infected people, but said she wasn’t worried

“I don’t feel sick or anything but it’s a formality,” she told the ABC.

She said she frequently commuted into the city and was surprised that cases had popped up in Avalon, which is about 37 kilometres from the Sydney CBD.

A man, also from Avalon, said it was the third test he had done at the Mona Vale clinic, but felt it was an important precautionary step.

“We heard there was a hotspot in Avalon… my wife has been to some of the locations where the people who tested positive have been,” he said.

“We are over 70 and we are concerned.”

The first cases in Sydney’s north came just hours after a van driver who transports international airline staff also tested positive for the virus.

There is no suggestion the infections are linked.

All five new infections came after nearly a fortnight without locally acquired infections in NSW.

The outbreak has already prompted concerns about whether the recently opened Queensland and Western Australian borders will again be shut to people from NSW over Christmas.

Before the latest diagnoses, WA Premier Mark McGowan had refused to rule out restrictions if further infections were detected in NSW.

“If the advice comes back that we need to put up a hard border, then we will,” he said on Wednesday.

Acting Queensland Premier Steven Miles said the government was not considering fresh border restrictions “at this stage”. But the next 48 hours would be important.

Elsewhere, Victoria notched up another day without cases in the community on Thursday. It has seven active cases, all in returned travellers in hotel quarantine.

-with agencies