Trials of an inhaled coronavirus treatment found that hospital patients who took the drug had a 79% lower risk of developing severe disease.

According to early results of the study, patients who received the drug, known as SNG001, were more than twice as likely to recover from Covid-19 as those who received a placebo.

The treatment has been developed by the pharmaceutical company Synairgen.

Previous studies involving asthmatic patients have shown that the drug is well tolerated, enhances the lungs’ anti-viral defences and improves lung function during cold or flu infection.

The current trial was carried out on a double-blind and placebo-controlled basis – meaning neither the researchers nor the 101 patients knew whether they were receiving SNG001, a special formulation of the naturally occurring anti-viral protein interferon beta 1a (IFN-beta), or a placebo.

It found that the odds of developing severe disease – needing ventilation or resulting in death – during the treatment period of up to 16 days were reduced by 79% for patients receiving the drug compared with patients who received the placebo.

Results of the study indicate that, over the treatment period, the measure of breathlessness was markedly reduced in patients who received SNG001.

Three people (6%) died after being randomly assigned the placebo, while there were no deaths among those who received the drug, Synairgen said.

In patients with more severe disease at time of admission, SNG001 treatment increased the likelihood of hospital discharge during the study, but researchers say the difference was not statistically significant.

Professor Tom Wilkinson, professor of respiratory medicine at the University of Southampton and trial chief investigator, said he is “delighted with the positive data produced from this trial”.

He added: “The results confirm our belief that interferon beta, a widely known drug that, by injection, has been approved for use in a number of other indications, has huge potential as an inhaled drug to be able to restore the lungs’ immune response, enhancing protection, accelerating recovery and countering the impact of Sars-CoV-2 virus.”

Professor Stephen Holgate, Medical Research Council clinical professor of immunopharmacology at the University of Southampton and co-founder of Synairgen, said the treatment “restores the lungs’ ability to neutralise the virus, or any mutation of the virus or co-infection with another respiratory virus such as influenza or RSV, as could be encountered in the winter if there is a resurgence of Covid-19.”

Speaking to members of the press on Monday, Prof Holgate added: “That’s one of the reasons we are really so excited about this, because it’s not like a vaccine, which is very specific for a particular set of structural molecules on the surface of a virus, it is the body matching its own immune response.”

Synairgen chief executive Richard Marsden said the second element of the trial will involve a further 120 patients in a home environment who are in the “at-risk” category.

“The objective here is to protect this vulnerable population and prevent them from going into hospital and accelerate their recovery,” he said.

Mr Marsden said patients wishing to take part in the home trial can visit www.covidtrialathome.com to see if they are eligible.