WHO warns of rush to use plasma therapy

EVIDENCE that convalescent plasma is effective in treating patients with coronavirus is “low quality”, the World Health Organisation said as the United States issued emergency approval for the use of the therapy.

On Sunday, the US Food and Drug Administration granted authorisation for the technique, but Soumya Swaminathan, the WHO’S chief scientist, said only a few clinical trials of convalescent plasma have produced results.

“At the moment, it’s still very lowquality evidence,” she said. “So we recommend that convalescent plasma is still an experimental therapy, it should continue to be evaluated in well-designed randomised clinical trials.”

The technique involves taking antibody-rich plasma from patients who have recovered from Covid-19 and giving it to those who are suffering from severe active infections in the hope they will recover more quickly.

Evidence is conflicting: one Chinese study showed plasma from people who have recovered from coronavirus failed to make a difference in hospitalised patients, while another, pooled analysis showed it can lower the risk of death.

One challenge, Dr Swaminathan added, was plasma’s variability, since it is drawn from many different people, producing a product that is less-standardised than monoclonal antibodies crafted in the lab.

Bruce Aylward, WHO senior adviser, added that beyond plasma’s efficacy, there were also potential safety risks that must be vetted.

“There are a number of side effects,” he said, ranging from mild fevers to severe lung injuries or circulatory overload.

“For that reason, the clinical trial results are extremely important.”