It took nine days for the New South Wales health department to contact Antoinette Chidiac after she visited Trim’s Fresh in Merrylands, western Sydney, where there was a positive Covid case in mid-July.
Across NSW, people have been experiencing long delays between visiting a high-risk Covid exposure site and being notified to isolate and test as a close contact, prompting warnings from one epidemiologist that the contact tracing system is “overwhelmed”, which would be “a recipe for disaster”.
For Liz Giusti in Liverpool, who visited a Sydney Woolworths in mid-July, and Jodie Wright, who also visited a Woolworths last month, there was no notification at all.
“I checked in to the supermarket QR code,” Giusti told Guardian Australia. “I later realised, after scrolling through my check-in history on the Service NSW app, that my visit was within the same hour as the positive case. But I still wasn’t alerted.
“I saw my local Woolworths on the NSW Covid-19 case locations map, which I had checked out of curiosity over a week after my visit,” Giusti said.
They are among many people Guardian Australia is aware of who have learned they were a close contact from sources such as neighbourhood Facebook community groups and supermarket social media statements, rather than NSW Health.
NSW Health stopped publishing lower risk exposure sites in greater Sydney in mid-August after the list ballooned to thousands of locations.
On Friday, Service NSW said customers would soon receive an alert inside the current check-in app if they had attended a venue of concern”, and said more changes to the app alert system would arrive “in coming weeks”.
But in the meantime, epidemiologists said it seemed clear the NSW system was struggling.
Emma Miller, a professor in epidemiology and infectious disease surveillance at Flinders University, said contact tracing was “the most important public health activity we can undertake in trying to manage Covid outbreaks and the pandemic”.
“That contact tracing process needs to be operating at an optimal level, which the Doherty model specifies.”
Underlying the Doherty Institute modelling, which the federal and state governments are relying on to ease restrictions once certain vaccination targets are hit, are assumptions about the efficiency of the contact tracing process.
In a National Contact Tracing Review presented to national cabinet in November 2020, the former chief scientist Dr Alan Finkel stressed that “reducing the duration” between Covid testing of a positive patient and quarantine of close contacts “to fewer than 48 hours” lowered community transmission “substantially”.
Rapid contact tracing was a mainstay of the fight to keep the pandemic at bay, Miller said.
“To then hear widespread anecdotes of close contacts whose NSW Health alert was late, or never came at all” was “evidence of a system no longer operating at optimal levels”, she said.
“We are starting to see fraying around the edges in the NSW system, where people are not being alerted of possible contact with Covid in an efficient manner.”
It was sign of “a contact system that is overwhelmed”, she said. “It is a recipe for disaster.”
Miller said such gaps in the system could cause rates of infection to increase.
“Especially with how contagious the Delta variant is. And we have other strains coming down the pipeline. The importance of high-quality contact tracing cannot be overstated.”
What is causing the delays?
NSW Health acknowledged that the Delta outbreak and growing case numbers had created “significant challenges” for the health system.
“Confirmed cases now receive a text message from NSW Health as soon as a positive result is reported,” a spokesperson said. They were followed up by NSW Health staff “as soon as possible” to conduct interviews in order to manually identify any additional close contacts.
“Where a high-risk exposure venue is identified from the case interview, QR code information is used to identify and inform people who may have been exposed at that venue,” the spokesperson said.
Dr Paul Gardner-Stephen, the chief technology officer at DEWC Systems, and an academic specialising in mobile communication infrastructures and informatics, also at Flinders University, said the QR check-in tracking system was extremely valuable.
“Without it, we’d be up the wazoo with Covid.”
But he said there were “a great many unknowns” in trying to gauge what was causing the widespread delay of close contact alerts.
“From the outside, it is difficult to tell if the NSW Health system has been able to muster enough resources onto the contact tracing task for the scale of this outbreak.
“The data is obviously there. In principle, you sign in with your QR code and within a few seconds it is sitting in a database.
“When you have a dozen cases, you can handle it. But once you reach over 1,000 cases a day, for the NSW contact tracing team to process all of those seems almost impossible.
“This is an unprecedented situation. It is the first pandemic in the information age that societies have had to tackle. You have complex systems interfacing between different government departments, you have privacy legislations. You have higher numbers than anticipated.”
Gardner-Stephen said the automated system may need to be “scaled up”.
“Depending on the complexity of their IT system and whether it was architectured to be flexible enough … the challenge for the government is to scale up as quickly as possible, given the absolute imperative to do so.”
The consequences of the system being overwhelmed were dire, Miller said.
“It means we aren’t getting a true sense of how large the problem is and how many people are at risk.
“Does the tree fall in the forest? If we aren’t managing case contacts efficiently, we will have a forest completely hollowed out before anyone really notices.”
