In Australia, federal government-funded research has revealed far more people have potentially been exposed to the coronavirus than anticipated.
Researchers from the Australian National University have now developed a new test which picks up previous Covid-19 infection in a patient's blood.
The study indicates eight in 3000 healthy and previously undiagnosed Australians had likely been infected with the virus.
"This suggests that instead of 11,000 cases we know about from nasal swab testing, about 70,000 people had been exposed overall," Associate Professor Ian Cockburn said.