The research released this week was funded by the Department of Health and largely involved researchers from the Australian National University’s John Curtin School of Medical Research, as well as deputy chief medical officer Nick Coatsworth.
Some 2991 elective surgery patients were screened, with 41 having antibodies to the virus.
This equates to 0.28 per cent or 71,400 Australians who could have had the virus based on a population of 25.5 million.
Noting the small sample size, Coatsworth emphasised the number of undetected cases was simply an estimate.
“It doesn’t precisely respond to reality,” he told reporters in Canberra.
“It’s not going to change our policy, we base our restrictions policy on the number of acute cases of COVID-19.”
Study co-lead Elizabeth Gardiner hopes antibody tests will be helpful for easing restrictions, as well as for the rollout of a potential coronavirus vaccine.
“It’s like a footprint for someone that had an exposure,” Gardiner told AAP on Wednesday.
The study came as the Actuaries Institute suggested hundreds more Australians than officially recorded could have died from COVID-19 early in the pandemic.
An Actuaries Institute research paper found an otherwise unexplained spike in deaths from pneumonia, stroke and diabetes, all causes of death related to COVID-19 in some way, during March and April 2020. At that time, testing for the virus was not widespread.
“The last week of March and the first week of April each had much higher deaths than predicted,” said Jennifer Lang, Convener of the Actuaries Institute’s COVID-19 Working Group.
It adds to the debate over classifications and whether people have died with, or of, COVID-19.
While it’s currently uncertain how long COVID-19 antibodies last for, they can last a long time for other viruses.
In regards to a vaccine, such testing could look at the power of the antibodies to protect against the virus.
Gardiner says it’s still safest for someone with antibodies to get the vaccine because it’s unclear how the virus mutates.
“We just don’t know enough yet about this virus.”
Given Coatsworth’s involvement in the research, Gardiner expects it to be discussed by the nation’s expert medical panel in regards to rolling out the blood tests across the community, particularly in schools.
Gardiner hopes they consider how it can help to restart elective surgeries.
“There’s a massive backlog of people waiting for elective surgery, we can probably open that up a bit wider and get people having their elective surgery with confidence.”
The study is currently under peer review for the Journal of Infectious Diseases, and the team are expecting to hear back within a few weeks.
“We’re very confident of the study and the peer review will make it even stronger,” Gardiner said.
The study was conducted over June and July, with the last blood sample taken on July 17 when Australia’s coronavirus cases were at about 11,000.
The paper notes reported cases are likely to only represent a fraction of actual infections, as 40 per cent of cases are mild, asymptomatic or undiagnosed.
The Department of Health’s website puts total confirmed coronavirus cases in Australia at 26,738 up until Tuesday.
-with Sean ParnellJump to next article