Hundreds of people are being turned away from COVID-19 testing clinics, while others are camping out in their cars to ensure they receive a swab, as long lines continue to cause chaos around the country.
The clinic on Plough Inn Road at Leumeah in Sydney's south-west has already closed, with police warning people to avoid it.
Barriers have also been erected at a clinic at nearby Liverpool, before mid-morning.
Further north, cars are also being turned away at Adcock Park in West Gosford.
At Coffs Harbour, some people have been queueing since 11pm yesterday, making the choice to sleep in their car rather than risk missing out.
Hundreds of cars are already lined up, with health authorities urgently requesting help from SES for traffic management.
Police have also warned that the testing clinic at Cessnock in the Hunter Valley would be closing at 11am today.
Queues also began early in Melbourne, where congestion has overwhelmed testing centres in recent days.
The state government is considering allowing asymptomatic people to clear themselves with a rapid antigen test at home.
If it returns a positive result the person will need to queue for a PCR test, but it's thought that the decision would ease pressure on health workers.
Hundreds of Queensland health workers are also struggling to get a test, telling 9News they were having to queue for hours.
So far, 55 health workers have tested positive for COVID-19, while a further 300 are in isolation.
Wait times in Queensland were around five hours, while those who do eventually get in to be tested then face a three-day wait for results.
Currently, Queensland and Tasmania are the only states to require a negative PCR test for incoming travellers.
An expert in COVID-19 testing says the mistake which saw 400 people given the wrong test results shows rapid antigen testing needs to be rolled out to relieve the pressure on PCR sites.
Histopath's operations director Greg Granger, who used to work at SydPath, which was responsible for the blunder, said the mistake shows the system is "overwhelmed."
"I can certainly confirm that the pressure is overwhelming and that alternative sources need to be found," he told Today.
"The rapid antigen testing is one that comes to mind.
"I can say with complete authority the systems they have there are entirely robust and the team in microbiology are world class."
He said pathology staff worked over Christmas and even if more sites were added, there wouldn't be staff to man them.
"This extraordinary demand is only going to get worse," he warned. "It is of concern for me. And it really should be a concern for the entire sector."