A major study has found that convalescent plasma does not reduce the risk of intubation or death for COVID-19 patients.

However, the study also revealed that the antibody profile in the blood of people who have had the virus is extremely variable and this may modify the response to the treatment.

The Canadian-led international research team found that patients receiving convalescent plasma experienced significantly more serious adverse events than those receiving standard care.

The majority of those events were an increased need for oxygen and worsening respiratory failure. However, the rate of fatal incidents was not significantly different from the control group of patients who did not receive the blood.

“It has been thought that the blood plasma of COVID-19 survivors would help those seriously ill from the virus but, unfortunately, it does not,” said Donald Arnold, co-principal investigator of the study, hematologist and professor of medicine at McMaster University.

“We are cautioning against using convalescent plasma to treat COVID-19 hospitalized patients, unless they are in a closely-monitored clinical trial.”