The World Health Organisation has updated its guideline on Covid-19 therapies to recommend against the use of convalescent plasma - a transfusion of blood plasma from someone who has recovered from Covid-19 – in treating infections.

Current evidence shows that convalescent plasma does not improve survival or reduce the need for mechanical ventilation, while it has significant costs, says the WHO.

An independent panel of experts looked at pooled data from 16 randomised controlled trials, including 16,236 patients with non-severe, severe, and critical Covid-19 infection.

While the evidence that convalescent plasma offers no benefits in non-severe patients was of high certainty, it was less so in the case of severe and critically ill patients.