The World Health Organization on Tuesday advised that plasma taken from the blood of recovered coronavirus patients should not be given to people with mild or moderate illness.
"Current evidence shows that it does not improve survival nor reduce the need for mechanical ventilation, and it is costly and time-consuming to administer," the UN health agency said in advice published in the British Medical Journal.
The hypothesis for using plasma was that the antibodies it contains could neutralize the novel coronavirus, stopping it from replicating and halting tissue damage.
However, several studies testing convalescent blood plasma have shown no apparent benefit for treating COVID-19 patients who are severely ill.
And a US-based trial was halted in March after it was found that plasma was unlikely to help mild-to-moderate patients.
