Study suggests more of us exposed to COVID-19 than known
As case numbers begin to drop, Australia seemingly begins to step closer to suppressing coronavirus. But alarming new research suggests that more people could have been exposed to the virus than previously thought.
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Blood samples taken from healthy Australians suggest more people could have been exposed to COVID-19 than previously thought.
Australian National University (ANU) researchers have developed a new way to test for “historic” cases and determine people who may have come into contact with the virus.
The test measures the body’s natural immune response and looks for antibody signatures in the blood, which show up if a person has been exposed to a virus.
They can then pinpoint if markers specific to COVID are present and how strong they are, to determine if a person is likely to have been exposed.
A total of 3000 people had blood tested between June and July as part of the research, of which 41 were found to have “some kind of evidence” of being positive.
This was narrowed down to just eight — through process of elimination, probability and logic — who researchers believe were likely to have been previously infected, or are a “true positive”.
“What we’re saying is that a small number of these people had it in the past,” ANU Associate Professor Ian Cockburn says. “Either those people had essentially what they thought was a cold … or maybe they never got tested. They may be asymptomatic people.”
“Those people we can say with really high confidence that they were exposed.”
Prof Cockburn estimated about one in 350 people had been infected by SARS-CoV-2 at the time of the study, and suggested this could mean the number of people exposed to the virus was as high as 70,000.
The research analysed samples of blood collected for a separate study from elective surgery patients in Victoria, New South Wales, South Australia and Western Australian, during the first wave of the pandemic.
That study, of which deputy Chief Medical Officer Dr Nick Coatsworth is an author, was then used as a basic for the ANU research.
Prof Cockburn said the research was “important public health information” to have going forward, especially in Victoria.
“These kinds of studies let us know how many people have had COVID, what proportion are asymptomatic,” he said.
“And we test a lot of people, but [it shows] what fraction of the burden that is capturing.”
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