A study led by researchers at Johns Hopkins Bloomberg School of Public Health suggests that a more widespread use of convalescent plasma could have significantly reduced the death toll during the first year of the COVID-19 pandemic. The research, published in the Proceedings of the National Academy of Science, estimates that thousands of lives could have been saved if convalescent plasma had been more broadly administered, especially to high-risk outpatients and hospitalized patients within the first few days of admission.
Potential Lives Saved
The study estimates that between July 2020 and March 2021, convalescent plasma treatment saved between 16,476 and 66,296 lives in the United States. The researchers analyzed weekly convalescent plasma usage data, national mortality data, and mortality reduction data from meta-analyses of randomized controlled trials to arrive at these figures. Furthermore, the study explored the potential impact of more extensive convalescent plasma use.
Researchers used optimistic assumptions, and they concluded that if 100% of patients hospitalized with COVID-19 had received high-titer convalescent plasma within three days of admission, between 37,467 to 149,318 (an approximately 125% increase) or between 53,943 to 215,614 (an approximately 225% increase) more lives could have been saved during the same period.
Impact on Hospitalizations
The study also assessed the potential for reducing hospitalizations through outpatient convalescent plasma treatment. The authors estimated that if 15% of outpatients had received convalescent plasma, between 85,268 and 227,377 hospitalizations could have been avoided. Increasing the outpatient treatment rate to 75% could have prevented between 426,331 and 1,136,880 hospitalizations.
Challenges and Recommendations
Arturo Casadevall, MD, PhD, Bloomberg Distinguished Professor at the Bloomberg School and senior author of the study, emphasized the potential of convalescent plasma as a readily available and cost-effective therapy. "This is a therapy that can reduce mortality, be immediately available, and is relatively inexpensive—we should be prepared to use it much more in a future infectious disease emergency or pandemic," he stated.
The researchers noted that initial studies on convalescent plasma effectiveness had mixed results due to challenges in ensuring sufficiently high anti-SARS-CoV-2 antibody concentrations and the administration of plasma to patients already severely ill. However, later studies, including a Johns Hopkins-led clinical trial, demonstrated that early convalescent plasma use in outpatients reduced the relative risk of hospitalization by 54%.
The authors recommend that public health preparedness plans for future outbreaks include the capacity to collect and deliver convalescent plasma at scale, highlighting its safety and lower cost compared to newer, patented COVID-19 treatments. The average cost of convalescent plasma in the U.S. was approximately $750 per unit during the pandemic.
Study Limitations
The authors acknowledged several limitations in their study. The exact number of convalescent plasma units used during the study period is not precisely known, and the mortality reduction estimates used to calculate lives saved varied widely. It is also uncertain whether these estimates accurately reflect the use and efficacy of convalescent plasma in clinical settings across the U.S.
Casadevall suggests establishing outpatient centers for early convalescent plasma treatment during future outbreaks, leveraging existing medical knowledge and practices without requiring new technology.
