According to the authors of the study, which found disposable tissues to be better than jet dryers at removing pathogens missed by ineffective cleaning, people should dry their hands with paper towels to avoid spreading the new coronavirus.

Global health authorities have highlighted the crucial importance of washing hands with soap and water to protect against Covid-19, which has killed tens of thousands and spread around the world.

"We believe that our results are relevant to the control of the novel coronavirus that is spreading at pace worldwide," said the authors, led by Ines Moura from the University of Leeds. "Paper towels should be the preferred way to dry hands after washing and so reduce the risk of virus contamination and spread."

Four volunteers had their hands contaminated using a bacteriophage – a virus that infects bacteria and is harmless to humans – and then did not attempt to wash the microbes away. They then dried their hands either with paper towels or a jet air dryer in a hospital toilet and went on to touch various surfaces including door handles, stair rails, phones and stethoscopes. 

Researchers found that using both paper towels and jet dryers reduced the contamination on hands.

But for 10 out of 11 surfaces sampled, the jet method left "significantly greater environmental contamination". Microbes were found on all surfaces touched after using the jet dryer, with contamination on average 10 times higher than after the use of paper towels.

"Clearly how much virus remains on peoples' hands after washing depends to a large extent on how efficiently people are at washing their own hands," said Paul Hunter, professor in medicine at the University of East Anglia, in response to the research.

"If people do not wash their hands properly then other people may be at risk if standing close to someone using such a jet dryer. This study reinforces the need to wash hands properly so as much virus is removed as possible before drying."

The study was due to be presented at this year's European Congress on Clinical Microbiology and Infectious Diseases (ECCMID) in Paris this month, which was itself cancelled due to the coronavirus pandemic.