The World Health Organization says a clinical trial in 52 countries will study three anti-inflammatory drugs as potential treatments for COVID-19 patients.
"These therapies - artesunate, imatinib and infliximab - were selected by an independent expert panel for their potential in reducing the risk of death in hospitalised COVID-19 patients," it said in a statement on the Solidarity PLUS trial.
The trial involves thousands of researchers at more than 600 hospitals, WHO director general Tedros Adhanom Ghebreyesus told a news briefing from Geneva.
Finland is one of the first countries to enrol patients in the Solidarity PLUS trial, he added.
"Finding more effective and accessible therapeutics for COVID-19 patients remains a critical need," Dr Tedros said.
"There are many variants and all variants can appear anywhere on the planet. And so having so many sites in so many different countries and regions will help us get to these answers as fast as possible," said Marie Pierre Preziosi, co-lead of the research and development blueprint at the WHO.
Artesunate is already used for severe malaria, imatinib for certain cancers and infliximab for diseases of the immune system such as Crohn's Disease and rheumatoid arthritis.
The WHO warned countries to come together to combat the fast-spreading Delta variant of the coronavirus and urged equitable access to essential countermeasures.
"At the current trajectory, we could pass 300 million reported cases early next year. But we can change that. We're all in this together but the world is not acting like it," Dr Tedros said.
The WHO last week called for a halt on COVID-19 vaccine boosters until at least the end of September as the gap between vaccinations in wealthy and poor countries widens.
The original Solidarity trial last year concluded that all four treatments evaluated - remdesivir, hydroxychloroquine, lopinavir/ritonavir and interferon - had little or no effect in helping COVID-19 patients.
The WHO expects final results from this trial next month.
So far, only corticosteroids have been proven effective against severe and critical COVID-19.
The WHO said artesunate, produced by Ipca, is used to treat malaria.
In the trial, it will be administered intravenously for seven days, using the standard dose recommended for the treatment of severe malaria.
Imatinib, produced by Novartis, is used to treat certain cancers. In the trial, it will be administered orally, once daily, for 14 days.
Infliximab, produced by Johnson and Johnson, is used to treat diseases of the immune system. In the trial, it will be administered intravenously as a single dose.
