COVID-19 convalescent plasma fails to improve clinical outcomes among hospitalized patients
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Compared with placebo, convalescent plasma with neutralizing anti-SARS-CoV-2 antibodies showed no improvement in hospitalized patients with COVID-19 at day 14, according to a study published in CHEST.
Further, outcomes for patients without endogenous antibodies also did not differ between treatment groups at day 14, according to researchers.
“Before the trial, we hypothesized that patients without endogenous antibodies (those ‘seronegative’ for anti-SARS-CoV-2 antibodies) would benefit the most from COVID-19 convalescent plasma treatment; trial results did not support this hypothesis,” Wesley H. Self, MD, MPH, senior vice president for clinical research and deputy director of the Vanderbilt Institute for Clinical and Translational Research, told Healio. “In the trial, convalescent plasma did not appear to provide benefit for patients who had their own endogenous antibodies nor those without endogenous antibodies.”
In a multicenter, blinded, randomized, placebo-controlled clinical trial, Self and colleagues analyzed 960 adults (median age, 60 years; 42.7% women; 19.2% Black) hospitalized with COVID-19 for less than 14 days to determine if convalescent plasma improved clinical outcomes in this patient population. They also sought to present efficacy estimates for patients with and without endogenous anti-SARS-CoV-2 antibodies.
As Healio previously reported, convalescent plasma failed to reduce respiratory failure or death in patients with moderate to severe COVID-19 pneumonia within 30 days.
Additionally, convalescent plasma was found to reduce the risk for hospitalization in patients with milder COVID-19 among outpatients if it was given to them within 9 days of symptom onset.
To further assess the efficacy of rigorously selected COVID-19 convalescent plasma with neutralizing anti-SARS-CoV-2 antibodies, researchers randomly gave patients one unit of COVID-19 convalescent plasma (n = 487) or placebo (n = 473) and assessed for illness severity in both groups after 14 days of treatment based on the seven categories of WHO’s COVID-19 Clinical Progression Scale.
Researchers analyzed illness severity between groups using a multivariable ordinal regression model that incorporated one-seventh support intervals (1/7 SIs) to quantify uncertainty.
Secondary efficacy outcomes included 28-day mortality, time to hospital discharge, time to recovery and various types of support-free days up until day 28.
Between the convalescent plasma group and the placebo group, researchers found no difference in the COVID-19 Clinical Progression Scale score at day 14 (adjusted OR = 1.04; 1/7 SI, 0.82-1.33).
At baseline, 144 patients from the convalescent plasma group and 139 patients in the placebo group were seronegative, meaning they lacked endogenous anti-SARS-CoV-2 antibodies. Again, no difference was found in COVID-19 Clinical Progression Scale score between patients receiving convalescent plasma vs. placebo whether they had endogenous antibodies (aOR = 1.15; 1/7 SI, 0.74-1.8) or not (aOR = 0.96; 1/7 SI, 0.72-1.3).
For 28-day mortality, researchers observed 89 deaths (18.5%) among those receiving convalescent plasma and 80 deaths (17.2%) among those receiving the placebo (aOR = 1.04; 1/7 SI, 0.69-1.58), with no difference overall or in the subgroups who were seronegative and seropositive.
Additionally, researchers found no difference between treatment groups for the other secondary efficacy outcomes in the total cohort and based on the presence of endogenous antibodies.
“Especially when combined with results from other similar trials conducted across the world over the past 3 years, we believe these findings provide strong support for clinicians not routinely administering COVID-19 convalescent plasma to patients hospitalized with acute COVID-19,” Self told Healio.
Self said future studies should look into other passive immunity therapies to ensure that they are clinically effective.
“While passive immunity therapies like convalescent plasma still have potential to assist with future pandemics, I believe rigorous evaluation of those therapies should be conducted before they are routinely administered to patients within usual care,” Self said.
For more information:
Wesley H. Self, MD, MPH, can be reached at wesley.self@vumc.org.