More than 100 new tests done to uncover stealth carriers in Queensland
More than 100 tests have been done to uncover stealth carriers of the novel coronavirus in Queensland since Monday, with three of those tests returning positive results.
Experts estimate 20 per cent to 30 per cent of people who are infected with COVID-19 have little to no symptoms, meaning they could be shedding the virus without realising they are sick.
Serology testing allows authorities to check if a person has recovered from infection without knowing they had it.Credit:Louise Kennerley
Previously, Queensland clinicians were only using one type of test to detect positive cases, by swabbing a person's throat or nose to examine the genetic code of the virus.
From Monday, a blood test called serology testing has been used to look for antibodies generated to fight the virus, allowing authorities to check if a person has recovered from infection without knowing they had it.
Health authorities are unsure about how 4 per cent of Queensland's coronavirus cases were contracted, which could mean they were infected by an asymptomatic person.
Serology testing helped authorities clamp down on a cluster of cases linked to a Cairns hospital laboratory this week.
Chief Health Officer Jeannette Young said work was under way to include random serology testing as part of the federal government's surveillance plan.
"We only started serology testing here in Queensland on Monday and we have done over 100 and three of those were positive."
Virologist Professor Ian Mackay, of the University of Queensland, said a "fair chunk" of people - he estimated as many as a third - likely had the virus without realising it.
"They are a threat because we don't know how many there are. The number of asymptomatic cases could vary from place to place and country to country."
He said increased serology testing at laboratories would help authorities get a better idea of how far the virus has spread but warned not everyone who had been infected with COVID-19 would have generated antibodies.
Professor Mackay said there was not enough evidence to know just how infectious silent carriers were.