Sky News host Chris Smith says Australians “should think twice before booking those Christmas flights” or at least check the refund policy with concerns any COVID-19 outbreak could cause certain states to slam borders shut again.

“Queensland has finally opened its borders to NSW from December 1, and likely, to Victorians, if they score another infection-free tally, tomorrow morning,” he said.

“How long that border will stay open will depend on how nervous they get if a cluster occurs in NSW or Victoria which can easily happen.

“Even today, wastewater analysis showed that the virus was in the Liverpool area of Sydney and 39 suburbs have been placed on alert.”

Global Biosecurity Professor Raina MacIntyre said, “we’ve seen throughout the pandemic, we’ve seen breaches of different kinds and we can expect that, at times, things won’t flow smoothly and there’ll be problems”.

Minutes from the New South Wales parliament revealed 169 security guards were sacked from hotel quarantine and four overseas travellers escaped from quarantine.

“At the peak of the epidemic in Victoria, around July, the number of cases was so great they couldn’t keep up with the contact-tracing and there were delays in contact-tracing,” Professor Macintyre said.

“So for every case, there might’ve been 10 to 20 contacts, and so on a day when they were having 500 cases a day, there might’ve been 5,000 or 10,000 contacts to trace.

“You can imagine if you don’t get through all of those within 24 hours, you’re going to have a bigger and bigger backlog each day… in hotel quarantine, it’s different because you have a fixed number.”