A new study shows that an experimental procedure that uses convalescent plasma—essentially blood from recovered patients—to treat COVID-19 is safe.
Researchers from Mayo Clinic, Michigan State University, and Johns Hopkins University, tracked 5,000 patients who received convalescent plasma transfusions and found few side effects and low mortality in those receiving the experimental treatment.
The study, a pre-print version not yet peer-reviewed, was posted Thursday on a health sciences server called Medrxiv (pdf). Pre-print studies report new medical developments that are not yet approved to be used to guide medical practice.
The researchers measured the impact of convalescent plasma transfusions on hospitalized adults with severe or life-threatening COVID-19 in the first four hours after receiving the experimental treatment, and then seven days on.
They found that what are known as serious adverse events (SAE) occurred in fewer than 1 percent of the treated patients after seven days, while the mortality rate was 14.9 percent, leading them to conclude the treatment is safe.
“Given the deadly nature of COVID-19 and the large population of critically-ill patients included in these analyses, the mortality rate does not appear excessive,” the researchers wrote in the study abstract.
“These early indicators suggest that transfusion of convalescent plasma is safe in hospitalized patients with COVID-19,” they added.
“The seven-day mortality rate was 14.9% reported here is not alarming, particularly because some of these plasma transfusions may be characterized as attempts at rescue or salvage therapy in patients admitted to the ICU with multi-organ failure, sepsis and significant comorbidities,” the researchers noted
In total, there were 36 reported SAEs, including 11 transfusion-related acute lung injuries, seven instances of transfusion-associated circulatory overload, and three cases of severe allergic transfusion reactions.
The study noted that a treating physician concluded that only two out of the 36 SAEs were definitely related to the convalescent plasma.
In April, the Food and Drug Administration (FDA) asked patients who had recovered from COVID-19 to donate plasma to help in the development of blood-related therapies.
The agency said people who have fully recovered from COVID-19 have antibodies in their blood to ward off future infections, and their plasma could potentially be used to devise treatments for severely ill patients.
“Convalescent plasma is an antibody-rich product made from blood donated by people who have recovered from the disease caused by the virus,” the FDA said in a release April 16, adding that there are studies suggesting “that convalescent plasma has the potential to lessen the severity or shorten the length of illness caused by COVID-19.”
Researchers of the above-described study, titled “Early Safety Indicators of COVID-19 Convalescent Plasma in 5,000 Patients,” noted that they were prompted to explore the new treatment after encouraging results from a study of the SARS-CoV-1 outbreak. That examination found that 80 patients in Hong Kong who were diagnosed with the illness, which bears some similarity to SARS-CoV-2, the scientific designation for COVID-19, were discharged earlier from hospital after receiving convalescent plasma within 14 days.
“These results are consistent with the notion that convalescent plasma may be an effective treatment of coronavirus infections and that earlier administration is more likely to be successful,” the researchers wrote.