It could prevent the transmission of coronavirus. For those infected it could shorten the duration of the illness and reduce the severity of symptoms.
The spray, developed by Canadian company SaNOtize, kills the bug in the upper airways, preventing it from incubating and going to the lungs, lab tests in the US and Britain showed.
Patients treated with spray saw an average viral log reduction of 1.362 in the first 24 hours, which shows a decline of around 95 per cent of the virus.
Within 72 hours the viral load plummeted by more than 99 per cent.
Dr Stephen Winchester, chief investigator of the UK trial, said: “I expect this to be a major advance in the global battle against the pandemic.
“Simply stated, I think this could be revolutionary.”