A recent study suggests that many lives could have been preserved during the initial year of the COVID-19 pandemic if convalescent plasma had been utilized more extensively. This is especially true for outpatients at a high risk for severe illness and for patients admitted to hospitals within their first few days of hospitalization.
A recent study by researchers from Johns Hopkins Bloomberg School of Public Health indicates that thousands of lives could have been preserved during the first year of the COVID-19 pandemic had convalescent plasma been utilized more widely, focusing on high-risk outpatients and hospitalized patients during their initial days of admission.
Convalescent plasma, taken from individuals who recovered from COVID-19, began being used early in the pandemic. This decision came from a group of physicians who referenced its previous success as a treatment during past infectious disease crises, such as the 1918-1920 influenza pandemic and the SARS outbreak from 2002-2004. Generally, plasma from patients who have recently recovered from infections like COVID-19 contains antibodies that can aid in blocking or diminishing the severity of the infection in other individuals.
During the first year of the pandemic, over 500,000 patients in the U.S. received convalescent plasma treatment.
In their new research, released online on October 1 in the Proceedings of the National Academy of Science, the authors estimate that administering convalescent plasma to hospitalized COVID patients may have saved between 16,476 and 66,296 lives in the U.S. from July 2020 to March 2021. To reach these conclusions, the researchers analyzed data on weekly usage of convalescent plasma, national mortality statistics, and meta-analyses of randomized controlled trials concerning the reduction in mortality related to convalescent therapy.
The team also evaluated the number of lives that could have been saved if convalescent plasma had been used more extensively among hospitalized COVID patients. Using the most favorable assumptions, they estimated that if all hospitalized COVID patients had been given high-titer convalescent plasma within three days of admission from July 2020 to March 2021, approximately 37,467 to 149,318 (a roughly 125% increase) to 53,943 to 215,614 (about a 225% increase) lives could have been saved in the pandemic’s first year.
From July 2020 to March 2021, a total of 647,795 units of convalescent plasma were administered to hospitalized COVID patients. This figure served as a gauge for the number of patients treated.
“This therapy can lower mortality rates, is readily accessible, and is relatively inexpensive, making it crucial for use in future infectious disease emergencies or pandemics,” remarks senior author Arturo Casadevall, MD, PhD, Bloomberg Distinguished Professor of Molecular Microbiology and Immunology at the Bloomberg School.
Casadevall was one of the staunch early advocates for convalescent plasma treatment at the pandemic’s onset. The principal author of the study, Quigly Dragotakes, PhD, is a postdoctoral fellow in Casadevall’s lab.
The researchers also assessed the number of hospitalizations that could have been prevented between July 2020 and March 2021 based on various assumptions:
- If 15% of outpatients had received convalescent plasma, it is estimated that 85,268 to 227,377 hospitalizations would have been avoided.
- If 75% of outpatients received convalescent plasma, between 426,331 and 1,136,880 hospitalizations would have been avoided.
Throughout the first year of the pandemic, convalescent plasma was only approved for patients hospitalized with COVID.
Initial research on the effectiveness of convalescent plasma in the United States and other nations produced mixed outcomes. According to Casadevall and colleagues, this inconsistency was partly due to the difficulty in ensuring that convalescent plasma had high enough anti-SARS-CoV-2 antibody concentrations. Additionally, many early studies administered convalescent plasma to patients who were already too ill to benefit significantly from the treatment.
Later investigations showed promise for convalescent plasma, including a clinical study led by Johns Hopkins that revealed early treatment among outpatients reduced hospitalization risk by 54%. (These findings were publicized in December 2021.)
The researchers emphasize that the application of convalescent plasma during the pandemic was safe and highlighted its cost—averaging around $750 per unit in the U.S.—which is less than newer, patented COVID treatments.
The authors urge that public health emergency preparedness for future outbreaks, epidemics, and pandemics include plans for large-scale collection and distribution of convalescent plasma.
However, the authors acknowledged several limitations in their study. Although the estimates of convalescent plasma units used during their analysis accounted for most of the treatments during the study period, the precise number of units used remains unclear. This lack of data is partly attributed to national Blood Centers of America not capturing local treatments in the initial pandemic stages. Moreover, the mortality reduction estimates they relied on greatly varied and may not have reflected the actual use and effectiveness of convalescent plasma therapies in clinical settings across the U.S.
“We must be prepared to establish outpatient centers to provide early treatment with convalescent plasma during future outbreaks,” says Casadevall. “Although this would involve setting aside hospital space, we wouldn’t need any new technology—this is well-established medical practice.”
