The virus that causes COVID-19 can survive on banknotes, glass and stainless steel for up to 28 days, much longer than the flu virus, Australian researchers said on Monday, highlighting the need for effective cleaning and handwashing to help combat the disease.

Findings from the study by Australia’s national science agency, CSIRO, appear to show that in a tightly controlled environment the virus remained infectious for longer than other studies have found.

CSIRO researchers said that at 20 degrees Celsius (68 degrees Fahrenheit) the SARS-COV-2 virus was “extremely robust” and remained infectious for 28 days on smooth surfaces such as plastic banknotes and glass found on mobile phone screens. The study was published in Virology Journal.

By comparison, Influenza A virus has been found to survive on surfaces for 17 days.

“It really reinforces the importance of washing hands and sanitising where possible and certainly wiping down surfaces that may be in contact with the virus,” said the study’s lead researcher Shane Riddell.

Experiments done at 20, 30 and 40 degrees Celsius (68, 86, and 104 Fahrenheit) showed the virus survived longer at cooler temperatures, smooth surfaces, and on paper banknotes rather than plastic ones.