The head of NSW’s busiest COVID-19 testing lab says rising numbers of people will return undefined coronavirus results as the testing blitz picks up cases that shed the virus weeks ago.

With the Prime Minister’s deadline for ramping up testing, contact tracing and containment approaching next month, the focus for pathology laboratories will be on interpreting inconclusive results, Professor Bill Rawlinson, director of Serology, Virology and OTDS Laboratories (SAViD), NSW Health Pathology based at Prince of Wales Hospital.

Senior hospital scientist Anna Condylios at work in the lab of the Prince of Wales Hospital. Credit:Kate Geraghty

“We are at the stage when individuals may only be positive for one of the several targets that PCR tests pick up,” Professor Rawlinson said, referring to the molecular testing performed samples collected by the nasal and throat swabs at COVID clinics.

“These indeterminate results are going to increase because there will be people who had [the virus] a long time ago and still have some residual RNA [ribonucleic acid],” he said.