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Monday, December 4, 2023

Blood test exposes missed COVID cases

Researchers at The Australian National University (ANU) have developed a new blood test capturing previous exposure to COVID-19.

Initial results suggest many more people have been exposed to the virus in Australia than have been detected so far. 

“We screened 3,000 blood samples provided by healthy people  around Australia for antibodies to the novel coronavirus SARS-CoV-2,” Associate Professor Ian Cockburn  said, who co-led the research with Professor Elizabeth Gardiner.  

He said the new highly sensitive test measures the antibodies that follow previous infection with SARS-CoV-2 and the study was conducted just before Australia’s second wave of outbreaks. 

“Our best estimate is that around 0.28% 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,” said Associate Professor Cockburn. 

The testing was conducted at ANU between 2 June and 17 July this year, ahead of Melbourne’s outbreak, and before testing had increased in response to the second wave.  

Researchers found eight in 3,000 healthy people were likely to have been previously infected after accounting for false positives. 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.

The new blood test, developed by the ANU research team, looks  for antibody signatures  in blood  to find evidence of previous  COVID-19  infection.  

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

Professor 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.” 

Director of The John Curtin School of Medical Research, Professor 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.” 

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