Swiss pharma giant Roche announced Tuesday promising results from clinical trials of an anti-Covid cocktail developed with US biotech firm Regeneron.

The results of the Phase 3 trial showed that the combination of the antibodies casirivimab and imdevimab "reduced hospitalisation or death by 70 percent in non-hospitalised patients with COVID-19," it said in a statement.

The cocktail also "significantly shortened the duration of symptoms by four days," from 14 to 10.

Roche said the tests were carried out on people believed to be at higher risk of contracting a severe Covid-19 infection, typically the elderly and those with underlying serious health conditions.

Several pharmaceutical companies have been developing antibody treatments which prevent the virus from replicating in the body, in the hope of finding an effective treatment to go alongside vaccines to combat emerging variants.

Roche noted that the treatment is the only monoclonal antibody combination which remains effective when confronted with the major variants, some of which are more infectious and cause more serious illness.

Levi Garraway, Roche's chief medical officer and head of global product development, said "new infections continue to rise globally with over three million reported cases last week.

"This investigational antibody cocktail may offer hope as a potential new therapy to high-risk patients -- particularly in light of recent evidence showing that casirivimab and imdevimab together retain activity against key emerging variants," Garraway said in a statement.

Roche meanwhile provided no indication on pricing.

Roche said its anti-Covid cocktail "significantly shortens" symptoms
Roche said its anti-Covid cocktail "significantly shortens" symptoms AFP / SEBASTIEN BOZON

But it told AFP that it had developed a pricing strategy based on countries' income level, according to World Bank data, in a bid to ensure "fair and affordable" access.

The trial results will now be passed on to regulators and submitted for peer review, it said.

The experimental cocktail is also part of several other studies still underway, with some 25,000 hospitalised patients having participated in various clinical trials.

French regulators earlier this month temporarily approved the use of two anti-Covid cocktails based on antibodies, including the one made by Roche and Regeneron, for early treatment of the disease in adults at risk of developing serious illness.

But they stressed that the treatments had yet to receive approval in the EU and that more incoming safety and efficacy data was still being evaluated.

And at the end of February, the European Medicines Agency did meanwhile provisionally approve use of the Covid-19 therapy made by Regeneron on its own, saying it prevented patients with the disease from getting worse.

The EMA said preliminary results showed treatment with REGN-COV2 reduced the amount of the virus in the back of the nose and throat and led to fewer medical visits.

Regeneron's synthetic antibody treatment was used to treat former US President Donald Trump after he contracted coronavirus last year.

It received emergency approval from US regulators last November.