Dr Nathan Bartlett, a University of Newcastle viral immunologist, said the drug would be used to "prevent diseases caused by common cold viruses and all respiratory viruses".

"We're currently testing it against a number of viruses including coronaviruses related to the current one. We've done extensive testing on influenza and rhinovirus," he said.

"Based on our understanding of this medicine's mechanism of action, we believe it's broadly applicable to any respiratory virus.

"It would potentially be effective in protecting against the current coronavirus disease - Covid-19 - however that is yet to be investigated directly."

Dr Bartlett said the drug - named INNA-X - "does look very promising".

"We're hoping to move it into phase one clinical trials before the end of this year."

This involves tests for safety and tolerance of the drug in people.

Dr Bartlett heads the Viral Immunology and Respiratory Disease Group at Hunter Medical Research Institute [HMRI].

He is working on the drug with a company called Ena Therapeutics.

"You'd take it as a protective measure. It's a way of priming your airways to be more resistant to infection."

It would be targeted towards those at greatest risk of serious illness caused by respiratory virus infection.

This includes the elderly and people with a range of conditions such as asthma, chronic obstructive pulmonary disease [COPD] and cystic fibrosis.

Dr Bartlett said there was a "massive unmet need in the way we treat or prevent viruses or respiratory virus infections".

"That's been the big issue with respiratory viruses in general - the lack of commercially available antiviral drugs."

He said the latest coronavirus disease - Covid-19 - is one of numerous respiratory viruses circulating among the population.

He said coronaviruses, rhinoviruses and influenza were "respiratory viruses that usually cause the clinical condition we know as the common cold".

"Most of us get mild symptoms. Occasionally you will get variants of these viruses - newly emerged viruses. These can lead to more severe symptoms, usually related to lower respiratory tract diseases such as bronchitis and pneumonia," he said.

He said the best protection was hand-washing and social isolation.

"But when you get a virus like this novel coronavirus in which there is no immunity within a community, the potential for this virus to spread very quickly is there."