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Canberra Today 12°/16° | Saturday, September 25, 2021 | Digital Edition | Crossword & Sudoku

New blood test: Many more people exposed to covid

Associate Prof Ian Cockburn, left, and Prof Elizabeth Gardiner at the John Curtin School of Medical Research at ANU. Photo: Jamie Kidston, ANU.

INITIAL results from a new blood test, which captures previous exposure to COVID-19, shows many more people have been exposed to the virus in Australia than have been detected so far. 

ANU researchers developed the new blood test, and Associate Prof Ian Cockburn, who co-led the research with Prof Elizabeth Gardiner, said: “We screened 3000 blood samples provided by healthy people?around Australia for antibodies to the novel coronavirus SARS-CoV-2.”

“Our best estimate is that around 0.28 per cent of Australians – one in 350 – had been infected with SARS-CoV-2 by that time. This suggests that instead of 11,000 cases we know about from nasal swab testing, about 70,000 people had been exposed overall.”

The new highly sensitive test measures the antibodies that follow previous infection with SARS-CoV-2. The study was conducted between June 2 and July 17, just before Australia’s second wave of outbreaks, ahead of Melbourne’s outbreak, and before testing had increased in response to the second wave.

Researchers found eight in 3000 healthy people were likely to have been previously infected after accounting for false positives.They say no one in the study had been identified as COVID-19 positive before.

The researchers say that even with a conservative view of the results, the number translates to potentially around 30,000 people with the virus at that time.

“When you get infected with?SARS-CoV-2?your body mounts an immune response?which?largely?consists of producing?antibodies,”?Associate Prof Cockburn?said.

“Our test measures?those antibodies showing who has previously been exposed to?coronavirus.

“Estimating how many people have had SARS-CoV-2 enables us to better understand the spread of the disease and how effective community testing is, and?can determine if there is evidence of herd immunity.”

Prof Elizabeth Gardiner said: “Our high-throughput robotic capacity enabled us to rapidly evaluate thousands of samples.”

“This will be important for assessing antibody levels in people receiving SARS-CoV-2 vaccines in the future,” she said.

Director of The John Curtin School of Medical Research,?Prof Graham Mann said: “These highly sensitive ways of detecting?antibodies are going to find many uses, especially in surveying for spread in the community, especially among people without symptoms.”

“It is another weapon in our armoury to combat further waves of the virus,” he said.

The study has been posted on the MedRxiv preprint server and has not been peer reviewed. 

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