Researchers at the CSIRO Disease Preparedness Center tested the longevity of SARS-CoV-2 at three temperatures in the dark, showing reduced survival rates as conditions became hotter, the Agency said Monday.

The scientists found that at 20 degrees Celsius (68 degrees Fahrenheit), SARS-CoV-2 was "extremely robust" on smooth surfaces — like mobile phone screens — that had survived for 28 days on glass, steel and plastic notes.

At 30 degrees Celsius (86 degrees Fahrenheit), the survival rate dropped to 7 days and dropped to just 24 hours at 40 degrees Celsius (104 degrees Fahrenheit).

The virus has survived for shorter periods on porous surfaces such as cotton — up to 14 days at the lowest temperature and less than 16 hours at the highest — the researchers said.

This was "significantly longer" than previous studies which found that the disease could survive on non-porous surfaces for up to four days, according to a paper published in the peer-reviewed Virology Journal.

Trevor Drew, director of the Australian Center for Disease Preparedness, said that the study involved drying samples of viruses on different materials before testing them using an "extremely sensitive" method that found traces of live viruses capable of infecting cell cultures.

"This doesn't mean that this amount of virus would be capable of infecting someone," ABC said to the public broadcaster.

He added that if a person was "careless with these materials and touched them and then licked your hands or touched your eyes or nose, you might get infected more than two weeks after they had been contaminated."

People 'far, far more contagious'

Drew indicated that there were several caveats, including that the study was conducted with fixed levels of virus likely to represent the peak of a typical infection, and that there was no exposure to ultraviolet light that could rapidly degrade the virus.

Humidity remained stable at 50%, according to the study, as increases in humidity were also found to be detrimental to the virus.

According to the CSIRO, the virus appears primarily to spread through the air, but more research was needed to provide further insight into the transmission of the virus through the surface.

"While the precise role of surface transmission, the level of surface contact and the amount of virus needed for infection is yet to be determined, determining how long the virus remains viable on the surface is critical to the development of risk mitigation strategies in high-contact areas," said Debbie Eagles of CSIRO.

The main message remains that "infectious people are far more infectious than surfaces," Drew told ABC.

"However, it may help to explain why, even when we get rid of infectious people, we sometimes get these breakouts again, sometimes even in a country that is considered to be free," he said.