Convalescent plasma reduces hospitalization risk in COVID-19
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Convalescent plasma, when administered within 9 days of symptom onset in patients with COVID-19, may reduce the risk for hospitalization, according to data published in The New England Journal of Medicine.
“While everyone was focused on treating people in the hospital after progression of disease, we saw the need to keep people out of the hospital rather than wait until they were near death,” David J. Sullivan, MD, of the Johns Hopkins Bloomberg School of Public Health, in Baltimore, told Healio. “We planned the highest level of evidence a randomized control trial to rigorously test how well it works when given early and at high dose. Our trial started in June of 2020 and was expanded throughout the United States to recruit participants in an evolving pandemic.”
To assess the safety and efficacy of polyclonal convalescent plasma in preventing hospitalization in patients with COVID-19, Sullivan and colleagues conducted a double-blind, randomized, controlled trial across 23 sites. A total of 1,225 patients with SARS-CoV-2 were randomized to receive infusions of either COVID-19 convalescent plasma or control plasma. Patients who had been previously hospitalized for COVID-19, were planning hospitalization within 24 hours of enrollment, or who had previous reactions to transfusion products were excluded from the study.
The primary outcome was COVID-19-related hospitalization within 28 days of receiving the transfusion. There were no pre-specified secondary outcomes. Monitored safety outcomes included transfusion-related events that appeared as “severe transfusion reactions, acute respiratory distress syndrome or adverse reactions of grade 3 or 4.” A medical monitor who was unaware of the group assignments evaluated adverse events and changes from baseline.
Between June 3, 2020, and Oct. 1, 2021, a total of 1,181 patients were included in a modified intention-to-treat analysis. Of those, 592 received convalescent plasma and 589 received control plasma infusions. There were no imbalances among the trial group, but men aged 65 or older were represented less than younger men and women, the researchers wrote.
According to Sullivan and colleagues, hospitalization occurred in 2.9% of patients who received convalescent plasma and in 6.3% of those who received control infusions, resulting in an absolute risk reduction of 3.4 percentage points (95% CI, 1-5.8) and a relative risk reduction of 54%. Results were similar in subgroups according to sex, BMI, vaccination status and status, and hypertension and diabetes status.
In all, 12 participants in the convalescent plasma group, and 26 in the control group, experienced disease progression requiring the use of oxygen in the hospital. Three patients in the control plasma group died. A total of 89 grade 3 or 4 adverse events were reported, with 34 of those occurring in convalescent plasma group and 55 in the control group.
“Antibodies work best in high dose given early in outpatient disease,” Sullivan said. “Polyclonal convalescent plasma maintains resiliency in defeating variants, including omicron, where we have had to remove monoclonals from our therapy tools. Post COVID-19 and post-vaccination plasma in high doses effectively neutralizes all variants to date, including omicron.
He added: “Convalescent plasma given in the outpatient has better efficacy than some allowed COVID-19 drugs, and when convalescent plasma was given within 5 days of onset, it appeared to associate with just as effective hospitalization prevention as the monoclonals.”
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