The painstaking process of piecing together the movements of the region's every coronavirus patient falls to a specialist team based in Wollongong.
At the peak of COVID-19 in the Illawarra Shoalhaven Local Health District - in late March - that team was tracing the contacts of scores of positive cases to identify others at risk and keep the wider community safe.
Contact tracing looks at where people have been, who they've seen over the period of time when they would have been infectious - in the case of COVID it's the two weeks prior to diagnosis that are scrutinised.
It's about breaking the chain of transmission - and that's something the ISLHD public health unit have done a pretty good job of.
There's been just one case of community transmission of COVID-19 in the past eight weeks - an Illawarra man in his twenties who was diagnosed two weeks ago.
The man's close contacts have been identified - though the source of his infection is still under investigation.
The ISLHD public health unit team - led by director Curtis Gregory - are actively monitoring the man and his contacts to ensure they remain isolated - and well.
"At its peak, we had 70 to 80 people with confirmed cases of COVID-19 in home isolation throughout the health district," Mr Gregory said.
"At the same time we had between 180 and 200 people who we'd traced as close contacts of those cases, who were also required to self-isolate for 14 days from the last contact.
"We contact the confirmed cases daily to monitor their symptoms, and their contacts every couple of days to check if they develop any symptoms and if so they will be tested."
Contact tracing is a method long used by public health, to curb the spread of any infectious disease - such as whooping cough, measles and influenza.
Working with the NSW Food Authority, the unit found traces of the rare strain of salmonella in apple strudle and a chocolate slice supplied to the IRT facilities by Betta Maid bakery.
Salmonella bovismorbificans was found in 31 infected residents - two of whom died - and the bakery was fined, and subsequently closed down.
A decade earlier, in 2005, the public health unit was also called in after an outbreak of the potentially deadly legionnaires' disease in Wollongong.
The outbreak - which lasted three months - led to the mass testing of Wollongong's air conditioning water cooling towers. Fourteen cases were identified - aged from 18 to 88 - with nine hospitalised.
"So we've had outbreaks and pandemics before that have been challenging and intensive," Mr Gregory said.
"What I think makes COVID-19 different is the extended timeframe plus the scale of the pandemic."
What's also different is that COVID has been identified as a category four notifiable disease under the public health act.
There's five categories - salmonella is a category two; legionella a category three. Other category four conditions include bird flu, SARS, tuberculosis, typhoid and ebola. HIV is a category five disease.
"Categories four and five are severe enough that authorities can serve a public health order if someone needs treatment or quarantine," Mr Gregory said, "or if they're non-compliant we can require them to stay at home in isolation."
Fortunately the district's public health unit has not needed to use this "emergency power" during the COVID crisis - with locals complying well with self-isolation requirements.
The unit received a surge in staffing during the pandemic's peak. With 114 of the 122 confirmed cases in the region now recovered, staffing levels are back to normal - yet there's flexibility to surge again if there's a second wave of coronavirus.
The Wollongong team features different specialists - epidemiologists, environmental scientists and registered nurses with expertise in public health.
Their process for contact tracing is intensive, and differs depending on how infectious the condition is - and how it's transmitted.
For instance salmonella is a food-borne illness so details of what patients have eaten and where they've sourced their food is required. Ross River fever is transmitted by mosquitoes, so an environmental audit is required.
HIV is a blood-borne disease while conditions like measles and COVID-19 are airborne so spread when someone coughs, sneezes or even talks.
"When you have that person to person transmission, that's when it's vital to identify all close contacts of the case," Mr Gregory said.
"And you need to look at how infectious a condition is. Measles for instance is a highly infectious disease caused by a virus that is spread from person to person through droplets in the air - and it lasts for half an hour in the airspace after the infected person has left.
"COVID is not quite as infectious and needs closer personal contact than measles, which is why physical distancing is so important, and is also spread through contact with surfaces. That's why cleaning and good hand hygiene is vital."
The incubation period is also important - for COVID it's generally three to seven days after exposure that people will get symptoms. But it can be up to 14 days - which is why health authorities have put the two-week isolation period in place.
Cases have to answer a lengthy questionnaire to identify contacts; using prompts to trigger their memory.
The Australian government's COVIDSafe app can assist if downloaded. However the district's public health unit has had limited opportunity to use the app, as new cases in recent weeks have predominantly been in people in hotel quarantine in Sydney.
The young man with the recent case of community transmission didn't have the app downloaded.
Using the information they've gathered, public health staff then need to determine whether there's been "incidental" or close contact.
"If an infected person has been in a shop for a few minutes that's seen as an incidental or casual contact," Mr Gregory said.
"But if they've been to some type of social event or worked in an office and had more extended contact with people, then there's a higher chance others will become infected."
The location - in a confined indoor space or outdoors - and the distance from other people are also taken into account.
"If you're standing three metres away from a person outside there's less chance of infection," Mr Gregory said, "than if you're one metre away in a shared office space.
"The longer you're in that environment, the higher the risk of exposure."
That's where the concept of physical distancing comes in - and the move away from personal greetings like hugs and kisses or shaking hands.
Those in the same household are always classified as close contacts, and home isolation has been a real challenge Mr Gregory said.
"Usually when a household member is sick, others in the household will care for them," he said. "Now we're asking them to isolate even from each other and that's been one of the challenges."
And while the first point of contact cannot always be uncovered, the priority remains to stop further transmission in the community.
"It's about making sure people who are sick with COVID, or potentially sick, are no longer circulating through the community," Mr Gregory said. "That they're not providing points of exposure to anyone else."
More than 38,000 people have undergone COVID testing in the region so far, giving the public health unit a good picture of what's happening in the community.
"We drew in additional staff in March/April to man the phones, to conduct well-being checks and look at case management and contact tracing, and can quickly upscale our response again if cases spike," Mr Gregory said.
"We're designed to be flexible - and to be quick. Once a case is confirmed, within four to six hours we have contacted and interviewed them so that we are then able to chase down their close contacts.
"So we'd urge people to keep getting tested, to maintain social distancing and hand hygiene - to help keep on top of COVID-19."
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