"In severely ill patients with Covid-19, the immune system overreacts, generating cytokines such as interleukin-6. Clinical trials have tested whether drugs that inhibit the effects of interleukin-6, such as 'tocilizumab' and 'sarilumab', benefit hospitalised patients. These studies have reported benefits," the WHO said in a statement.

The WHO recommendation follows research published on 6 July in the Journal of the American Medical Association, which analysed 27 studies in 28 countries involving nearly 11,000 patients, concluding that treatment with drugs that block the effects of interleukin-6 decreases the risk of death and the need for mechanical ventilation in hospitalised patients.

The research, coordinated by WHO in partnership with UK institutions King's College London, University of Bristol, University College London and Guy's and St Thomas NHS Foundation Trust, also concluded that 'tocilizumab' and 'sarilumab', commonly indicated for rheumatoid arthritis, were most effective when given with corticosteroids.

"In hospitalised patients, the administration of one of these drugs in addition to corticosteroids reduces the risk of death by 17 percent compared to the use of corticosteroids alone. In non-ventilated patients, the risk of need for mechanical ventilation or death is reduced by 21 percent compared with the use of corticosteroids alone," the WHO said.

"Pooling the results of studies from around the world is one of the best ways to find treatments that will help more people survive Covid-19. We have updated our clinical care treatment guidance to reflect this latest development," said Janet Diaz, WHO's clinical management officer for health emergencies.

For Manu Shankar-Hari, MD, professor of critical care at King's College London, this research has proven that "interleukin-6 antagonists reduce Covid-19 deaths, i.e. save lives and prevent progression to severe disease requiring respiratory support with a ventilator".