Early data from a clinical study by Mayo Clinic and partners has found that investigational convalescent plasma is safe for the treatment of severely ill patients with Covid-19.

The findings are based on analysis of safety data from the initial 5,000 hospitalised patients transfused with convalescent plasma under the US Food and Drug Administration (FDA)’s Expanded Access Program (EAP) for Covid-19.

According to researchers, the report involved assessment during the first seven days after transfusion in patients hospitalised with severe or life-threatening Covid-19, or those at high risk of progressing to severe or life-threatening condition.

Out of all patients, 66% were in an ICU and around 20% had multi-organ dysfunction or failure.

Meanwhile, serious adverse events relating to transfusion of the plasma were observed to be less than 1%. The seven-day incidence of mortality was 14.9%.

Though the study was not intended to assess the efficacy of convalescent plasma, a seven-day mortality incidence of 14.9% is said to suggest ‘no signal of toxicity beyond what is expected in plasma use in severely ill patients’.

Researchers plan to collect and review more safety data and continue studies on efficacy of this antibody-based therapy for Covid-19.

Mayo Clinic EAP head Michael Joyner said: “This is just the beginning of the reporting process. We are optimistic but must remain objective as we assess increasing amounts of patient data.”

As of 11 May, the EAP for convalescent plasma enrolled more than 14,000 patients and more than 8,900 patients were infused.

In addition to Mayo Clinic, the convalescent plasma programme involves Johns Hopkins University, Icahn School of Medicine at Mount Sinai, and Michigan State University, along with other academia and government agencies.