The arthritis drug tocilizumab saves lives and accelerates recovery in patients admitted to hospital with Covid-19, an extensive UK trial has confirmed.

The Recovery trial run by Oxford university studied 4,000 people who needed oxygen therapy but were not in intensive care. Tocilizumab cut patients’ mortality risk by about 15 per cent, while reducing the need for mechanical ventilation and shortening the time in hospital.

“This is a very significant step forward,” said Professor Martin Landray, joint chief investigator. “The benefits of tocilizumab come on top of those from dexamethasone, so we now have two therapies that together will cut your chance of dying from Covid in hospital by between a third and a half.”

His colleague Professor Peter Horby, the other chief investigator, said: “Previous trials of tocilizumab had shown mixed results, and it was unclear which patients might benefit from the treatment. We now know that the benefits of tocilizumab extend to all Covid patients with low oxygen levels and significant inflammation.”

Tocilizumab is made by Roche of Switzerland and sold under the trade names Actemra and RoActemra to treat various forms of arthritis. The company says it has been prescribed to 1.6m people in 110 countries over the past 10 years.

Asked whether there will be enough tocilizumab available to treat Covid-19 patients, the company said: “We work urgently to accelerate manufacturing capacity to maximise production wherever possible, with the goal of increasing available supply globally.”

A single infusion for a Covid patient costs the NHS between £500 and £1,000, doctors say. Although biosimilars — generic versions of tocilizumab — are being developed, they are not yet available in the UK.

The drug damps down excessive activity by part of the body’s immune system, a cause of symptoms in both arthritis and serious Covid-19. It works by blocking the receptors in human cells that respond to a messenger molecule called interleukin-6. IL-6 plays a key role in activating biological inflammation.

“Because we are targeting the immune response to Covid rather than the virus itself, tocilizumab therapy will not be affected by the evolution of future variants of the virus,” said Landray.

A related arthritis drug called sarilumab — also an IL-6 receptor blocker — has shown some evidence of effectiveness against severe Covid-19 in smaller trials but Landray said confirmatory data were needed.

Dr Charlotte Summers, a lung specialist at Addenbrooke’s Hospital in Cambridge and a member of the independent UK Covid-19 Therapeutics Advisory Panel, said: “The Recovery trial findings about tocilizumab are really exciting. I would give a single intravenous dose to anyone with Covid-19 who is sick enough to come into hospital and needs oxygen.”

Athimalaipet Ramanan, professor of paediatric rheumatology at the University of Bristol, said: “After dexamethasone, this is the most significant advance in the treatment of Covid that has an impact in reducing deaths. Recovery has clearly shown the importance of doing large clinical trials to address key questions.”