Benjamin Tang had braced himself as he watched news footage from emergency department around the world over-run by the 2009 swine flu pandemic; the hallways clogged with patients and staff pushed to breaking point.
His own intensive care unit at Nepean Hospital had treated huge numbers of seriously ill patients with the infection who made it through triage.
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"When I looked at their records I realised many of these people had presented to other EDs prior to coming to us, but no one had picked up that they were really very sick," Dr Tang said.
"Influenza can sometimes kill otherwise healthy people in the prime of their lives. No one was able to identify patients who were at high risk of developing pneumonia and could die.
![In a world first, Dr Ben Tang and co-researchers have developed a blood test to predict which flu patients will develop ...](http://web.archive.org./web/20170617100854im_/https://www.fairfaxstatic.com.au/content/dam/images/g/w/r/u/t/3/image.related.articleLeadwide.620x349.gwrnd2.png/1497578047687.jpg)
"Their symptoms were almost identical to most other patients who just had the simple flu and could have been sent home," said the intensive care doctor at Nepean Hospital and researcher at Westmead Institute for Medical Research.
"That's when I thought maybe we could come up with a way that would help front-line doctors identify which patients would need intensive care and which patients they could send home," he said.
In a world first, Dr Tang and co-researchers have developed a blood test to predict which flu patients will develop potentially life-threatening secondary infections that demand urgent medical treatment.
Currently doctors can only test for the presence of the influenza virus, but can not determine which of their patients will be at high risk of rapid deterioration.
![Dr Ben Tang has developed a way of predicting if people are susceptible for the flu virus.](http://web.archive.org./web/20170617100854im_/https://www.fairfaxstatic.com.au/content/dam/images/g/w/r/v/r/7/image.related.articleLeadwide.620x349.gwrnd2.png/1497578047687.jpg)
The High-risk Influenza Screen Test (HIST) measures an early warning signal – a single-gene biomarker dubbed IF127 – released into a patient's bloodstream that mobilises their immune system against serious infection, the researchers reported in the European Respiratory Journal published on Thursday.
The researchers had cracked the genetic code released by immune cells that warn the body of serious infection, such as pneumonia triggered by the influenza virus, found the clinical trial of more than 1000 patients and laboratory testing, culminating in the largest biomarker study of influenza virus infection.
"We're eavesdropping on the immune system to pick up when the body first mounts a defence against a serious, life-threatening, infection," Dr Tang said.
The test's 90 per cent accuracy rate was "unprecedented" for an infectious diseases screening test, Dr Tang said. The risk of missing one in 10 patients with serious infections was a "pretty good trade-off" for such a test, he said.
It would enable doctors to take a patient's blood sample and get a result within the critical 24-hour window.
"The earlier the treatment the better chance of survival. Without adequate and timely intensive care the risk of dying was over 50 per cent," Dr Tang said.
Swift and appropriate treatment could cut the risk of death threefold, he said.
One in five Australians will contract influenza this year, and it kills 1500 to 3500 people each year, including an estimated 800 to 1000 people in NSW, according to government modelling.
The flu is responsible for 18,000 hospitalisations nationally every year, and costs the health budget $85 million annually.
NSW Health recorded 35,409 influenza notifications from late June to late September in 2016 and at least 191 patients with influenza were admitted to intensive care or coronary care units.
"The early warning means we have a greater chance to treat the patient's infection before it overwhelms them and potentially kills them," Dr Tang said.
The test could play a critical role during pandemics by identifying those at greater risk of serious complications when there may be delays in developing vaccines for specific flu strains, Dr Tang said.
![MEXICO CITY - APRIL 29 2009: People sit in the waiting room at the Mexico City Navy Hospital to be checked for flu-like symptoms.](http://web.archive.org./web/20170617100854im_/http://www.smh.com.au/content/dam/images/g/w/r/n/k/8/image.imgtype.articleLeadwide.620x349.png/1497496764062.png)
The test will enable doctors to get a result within the critical 24-hour period. Photo: Joe Raedle
But it still had many hurdles to jump before it could be routinely used.
The next step for researchers was to assess its cost benefit and impact on patient outcomes and health budgets, the researchers concluded.
The Australian-patented test has patents pending in the US, Europe and China. The researchers were seeking a commercial buyer before the test could apply for approval with Australian and international medical regulators.