Coronavirus testing at the Blackwater Showgrounds. Photo - Steve Vit
Coronavirus testing at the Blackwater Showgrounds. Photo - Steve Vit

COVID-19 test accuracy probed following the Blackwater case

Following revelations Blackwater man Nathan Turner returned a false positive COVID-19 test after his death, questions have been raised regarding the accuracy of testing.

According to Co-Division Head of the Population Health and Immunity Division at The Walter and Eliza Hall Institute in Melbourne Professor Ivo Mueller, current testing does have some areas of weakness.

Professor Mueller said the current testing's main problem revolved around sensitivity.

"I think the test we have is very accurate, but it needs to be checked," he said.

"There is an inherent problem in terms of sensitivity, if the viral load is too low it will not be picked up, or not reliably picked up."

Should a patient get tested too early on in their sickness or too late into their recovery, tests may not be able to identify the virus.

Although this problem is not ideal, Mr Mueller said it was easily controlled through 'doing more than one test'.

"The good situation we have here in Australia is the infection rates are so low that our laboratories are retesting positives on a regular basis," he said.

"It's unfortunate in this case [Blackwater] that there was a false positive that wasn't confirmed, but I think generally our systems are very robust and particularly because the infection rates are low, we can really cross check things really well."

Mr Mueller also stressed the idea COVID-19 tests did not work autonomously but relied on several other factors.

"The test doesn't work on its own, it's part of a system that includes the test, the sample collection, the quality control, the quality insurance and then also how the results are communicated," he said.

When it comes to antibody testing, Mr Mueller is less enthusiastic about their accuracy.

Due to a range of factors, including how different people's bodies react to viral infections, antibody testing varies in accuracy.

Mr Mueller said antibody testing had the potential to be able to help health professionals understand the dynamic of the infection.

"We have technology in some of our work with malaria that allows us to see antibodies as a way to tell not just if somebody has been exposed, but when they were exposed. So we can differentiate if someone was exposed in March or more recently," he said.