In a randomised trial of 100 patients admitted to hospital with COVID-19, those who received an inhaled formula of the protein interferon beta were at 79 percent lower risk of developing severe disease compared to those who received a placebo.
They were also more than twice as likely to make a full recovery compared with the control group.
The firm behind the treatment, known as SNG001, said the preliminary results suggested "a major breakthrough" in the pandemic.
"We are all delighted with the trial results announced today, which showed that SNG001 greatly reduced the number of hospitalised COVID-19 patients who progressed from requiring oxygen to requiring ventilation," said Richard Marsden, CEO of Synairgen.
The results published Monday have not yet been peer-reviewed and the sample size is relatively small.
But if confirmed the treatment could revolutionise the way COVID-19 is dealt with in hospitals.
Game changer
Interferon beta is a naturally occurring protein, commonly used to treat multiple sclerosis.
It forms part of the body's natural fight against infection, and the novel coronavirus suppresses its production in an attempt to evade an immune response.
Delivering the protein directly into the lungs of patients is designed to trigger a robust immune response to the virus, even in patients whose immune system is already weakened by infection.
"The results confirm our belief that interferon beta... has huge potential as an inhaled drug to be able to restore the lung's immune response," said Tom Wilkinson, professor or respiratory medicine at the University of Southampton.
He said the trial showed SNG001 was effective in "enhancing protection, accelerating recover and countering the impact of SARS-CoV-2 virus."
Naveed Sattar, professor of metabolic medicine at the University of Glasgow said the new treatment "could be a game changer".
"With small (trial) numbers comes less certainty on the true level of benefit, or whether benefits vary between people with differing risk characteristics," said Sattar, who was not involved in the research.
"Such work would require a larger trial but, even so, these results are very exciting."
There are currently a number of treatments available for patients hospitalised with COVID-19.
Last month a Britain-based team of researchers lead by the University of Oxford announced they had successfully reduced the risk of death among seriously ill patients by administering the commonly available steroid dexamethasone.
Several countries have also issued the emergency authorisation for treatment with anti-viral remdesivir.
Agence France-Presse
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