Medics across the UK have been told to consider the asthma drug budesonide for certain coronavirus patients who are ill with the infection at home.
While those on ventilators or oxygen in hospital are routinely given the steroid dexamethasone, less serious cases were advised to just rest, drink plenty of fluids and take painkillers to ease any fever.
With at-home patients still often feeling seriously unwell, scientists from the University of Oxford found inhaling budesonide twice a day for two weeks speeds up an individual's self-reported recovery by 72 hours.
Although only interim results of an ongoing study have been released, this has prompted the UK's Medicines and Healthcare Products Regulatory Agency (MHRA) to issue an alert recommending healthcare professionals consider budesonide on a "case-by-case basis".
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Budesonide is an inhaled corticosteroid, which are known to ease inflammation; a key driver of coronavirus complications.
Laboratory studies suggest budesonide also reduces the coronavirus' replication and expression of a cell's Ace2 receptor, which the infection uses to invade the body.
"It is encouraging to see the NHS has announced it now permits off-label use for inhaled budesonide in primary care on a case-by-case basis following the results from the Principle trial," said co-lead investigator Professor Chris Butler.
"We all look forward to the full findings from the trial and any further recommendations on ways GPs can treat COVID-19 [the disease caused by the coronavirus] patients in their homes."
Matching the trial participant criteria, budesonide is only being recommended for patients with a confirmed coronavirus infection who are enduring ongoing symptoms that appeared within the past 14 days.
They must also be aged 65 or over with no underlying health issues, or 50 or older with a long-term medical condition.
The MHRA's interim statement stresses budesonide is not being advised for routine use and "recommendations may change as more data become available".
Speaking of the Principle study, the results of which are yet to appear in a peer-reviewed journal, Professor Butler said: "You can be pretty damn sick with this thing even if you don't require oxygen. People will [generally] only be admitted to hospital if their oxygen is running low.
"You won't be admitted for a trivial reason and you can be really really sick with this [virus] at home."
Professor Butler, who has overcome the coronavirus himself, added: "If someone could have taken three days off my illness duration, I would have been extremely grateful."
This arm of the Principle trial was initiated after it was observed relatively few asthma and chronic obstructive pulmonary disease patients were treated in hospital with the coronavirus, with inhaled corticosteroids potentially being protective.
To learn more, the Oxford scientists analysed over 1,700 participants who tested positive for the coronavirus.
They were given either "usual care", defined as largely "supportive" therapies like paracetamol, or usual care plus 800 micrograms of budesonide twice a day.
There was no placebo comparison, which is considered the gold standard of research.
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Results reveal the time to "self reported recovery" was three days shorter in those on budesonide.
This was true regardless of the participant's age, symptom severity or duration, or underlying health.
"Three days shorter [ill health] certainly sounds worthwhile to me," said Professor Kevin McConway from The Open University, who was not involved in the study.
Just under a third (32%) of those on budesonide recovered within 14 days, versus around one in five (22%) in the usual care group.
They also "subsequently remained well until 28 days" and reported "greater wellbeing after two weeks".
Among the 92% of the participants "who had the opportunity to contribute data for 28 days follow up", 8.5% in the budesonide group were hospitalised or died with the coronavirus, versus 10.3% of those just on usual care.
"Since fewer than expected people were admitted to hospital in the trial, and with COVID-19 cases and hospitalisations continuing to drop in the UK, it is not clear from this interim analysis whether budesonide reduces hospitalisations," wrote the scientists.
More data will be revealed once the 28 day follow up analysis is completed for all the participants.
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The scientists believe their results could change how the coronavirus is treated in the early stages of ill health at home.
According to co-trial investigator Dr Gail Hayward, a suitable drug "needs to be a relatively cheap treatment, easy to use, have few side effects and wide availability".
"Budesonide has all these characteristics," she added.
When asked about the drug's price, Dr Hayward said: "Working out the treatment cost is complicated because it involves the overall picture. The cost of the inhaler itself is about £14 [$19.27]."
Professor Butler added: "We anticipate medical practitioners around the world caring for people with COVID-19 in the community may wish to consider this evidence when making treatment decisions, as it should help people with COVID-19 recover quicker."
Principle was launched in April 2020 with "the intention drugs shown by the trial to have a clinical benefit could be rapidly introduced into routine NHS primary care".
The ongoing trial is evaluating a range of potential at-home treatments to reduce a coronavirus patient's recovery time, while preventing hospital admissions and deaths.
In January 2021, the Principle scientists found the antibiotics azithromycin and doxycycline "are not effective treatments for COVID-19 in the early stages of the illness, changing clinical practice in the UK and internationally".
"Unlike other proven treatments, budesonide is effective as a treatment at home and during the early stages of the illness," said co-trial investigator Professor Richard Hobbs.
"This is a significant milestone for this pandemic and a major achievement for community-based research."