Convalescent Plasma Didn't Help High-Risk COVID Patients: NIH

Ralph Ellis

August 20, 2021

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A study says convalescent plasma did not stop the progression of COVID-19 in high-risk patients when given during the first few weeks of their symptoms, the National Institutes of Health said in a news release.

A clinical trial using the convalescent plasma was stopped in February because the plasma didn't slow down the infection as hoped, the release said.

"We were hoping that the use of COVID-19 convalescent plasma would achieve at least a 10% reduction in disease progression in this group, but instead the reduction we observed was less than 2%," said Clifton Callaway, MD, the clinical trial's principal investigator and a professor of emergency medicine at the University of Pittsburgh.

"That was surprising to us. As physicians, we wanted this to make a big difference in reducing severe illness and it did not."

Convalescent plasma, also called survivor's plasma, comes from the blood of patients who have already recovered from COVID-19.

In August 2020, the FDA granted Emergency Use Authorization to allow doctors to give convalescent plasma to hospitalized patients with COVID-19. Scientists wanted to know if the plasma would slow down the progression of the virus in recently infected people who were not so sick that they required hospitalization.

Of the 511 people in the study, the disease progressed in 77 (30%) in the COVID-19 plasma group compared with 81 patients (31.9%) in the placebo group. The reason the intervention did not produce the expected results is unclear, Callaway said.

"The results show that convalescent plasma does not appear to benefit this particular group," said Nahed El Kassar, MD, a study co-author and medical officer in the Blood Epidemiology and Clinical Therapeutics branch of the National Heart, Lung, and Blood Institute (NHLBI) Division of Blood Diseases and Resources.

"But the findings answer an important clinical question and may help bring researchers a step closer to finding more effective treatments against this devastating disease."


NIH: "NIH study shows no significant benefit of convalescent plasma for COVID-19 outpatients with early symptoms."

FDA: "FDA Issues Emergency Use Authorization for Convalescent Plasma as Potential Promising COVID-19 Treatment."