After a dozen days without a coronavirus case, the mystery cluster in Sydney’s west has authorities racing to find its origin before it spreads further.
But experts say the cases may be the tip of the iceberg.
On Thursday, NSW confirmed 12 more coronavirus cases after its 12-day streak – with four linked to returned overseas travellers and another four connected to the Liverpool Hospital dialysis cluster.
However, the origin of the four mystery community transmission cases in south-western and western Sydney is what authorities are trying to find.
And with the fourth case confirmed as a student who attended Sydney’s Macquarie University, contact tracers are moving to stop the spread.
The university’s sports and aquatic centre and 10 Hadenfeld Avenue building were closed on Thursday for deep cleaning.
Fortunately, NSW has suppressed clusters before and the second wave in Victoria has provided clues as to how to respond more effectively.
Victoria’s health department has learned from its early missteps in tracing coronavirus clusters and NSW has the benefit of that knowledge, Deakin University epidemiology chair Professor Catherine Bennett says.
“Victoria’s response to outbreaks now makes the response at the start pale in comparison,” Professor Bennett told The New Daily.
“NSW had the heads up each time their community transmission has sparked up, so it has always been on the front foot.”
Despite a promising 12-day run without a new case, the community transmission proves the virus still remains undetected throughout NSW.
The size of the issue is not yet known, with venues across Sydney’s west tagged as potential transmission points and Premier Gladys Berejiklian flagging that more locations are expected to be added to the list.
“NSW has had few restrictions for a while now so it makes it harder for them to rule our hidden asymptomatic and/or untested cases that might still be passing the virus on at low levels in the community,” Professor Bennett said.
“It was a good sign the wastewater detected virus where at least one of these cases lives – shows that system is working.”
Health authorities connected two of Wednesday’s mystery cases.
NSW chief health officer Kerry Chant said a man in his 50s and a woman in her 50s had been linked.
“What has subsequently transpired is a household contact of the gentleman in his 50s is actually a co-worker of the lady in their 50s,” she said.
“They both are healthcare workers who work at a private healthcare clinic.”
Premier Berejiklian said this week’s cases in Sydney had shown that some businesses were not properly complying with COVID rules.
“It makes the job of our contact tracers that much more difficult if businesses aren’t doing the right thing. And I have no patience any more for businesses, in particular, who aren’t doing the right thing,” she said.
How does Victoria’s and NSW contact tracing stack up?
Victoria’s health department continues to suppress the ‘‘complex but manageable’’ outbreaks in Melbourne, but there is hope the metropolitan region can move to fewer restrictions in the weeks ahead.
“The current two weeks will hopefully demonstrate that the new aggressive outbreak-control techniques are working to close down the current spread,” Professor Bennett said.
“It will give the health department the confidence that they have a system that can work as restrictions ease as they are containing the outbreaks so quickly, wider population movement has less impact on the outcome.
“Just as has been the case in NSW these last months without blanket restrictions.”
New Zealand has taken its contact tracing to a whole new level, even tracing the origin of two cases back to a rubbish bin.
“While we cannot be certain, our hypothesis is that the virus may have been transmitted to a person via the surface of a rubbish bin which was used by another returnee who was likely infectious at the facility,” the NZ Ministry of Health said about the September cases.
A team of health officials carried out an extensive investigation, including viewing CCTV footage and a bin was identified as a common factor.
“This is not dissimilar to the case at the Rydges [hotel] in Auckland, where we believe a maintenance worker may have picked the virus up from pressing a button on a lift shortly after someone with COVID-19 used it.”
Meanwhile, in the UK, the national testing system has had another setback with Swiss pharmaceutical giant Roche saying problems at a new warehouse have delayed the dispatch of some products.
Roche is the main supplier of diagnostic tests to the National Health Service Test and Trace program, which has already suffered setbacks including a technical glitch that delayed reporting of 15,000 positive results.
Roche said the delay in dispatching some of its diagnostic products to the NHS was caused by unforeseen problems that arose during a switch from an old warehouse to a new UK distribution centre in September.
NHS Test and Trace has already struggled to match government promises of a “world-beating” system, with testing capacity failing to keep up with a surge in demand in September.
Last week’s technical glitch meant contact tracing relating to 15,000 infected people was delayed.