Humanity has recently faced two significant viral outbreaks: a hantavirus outbreak on a cruise ship and the resurgence of Ebola in Africa. Currently, there are no vaccines or antiviral treatments for these viruses. Supportive therapy is the main available treatment strategy. Medical experts often emphasize the importance of quarantine and isolation, as well as developing new therapies. However, a therapy that is already accessible but often overlooked is convalescent plasma.
Convalescent plasma involves using antibodies from recovered individuals to aid those currently infected. This method has been employed in infectious disease emergencies since the early 20th century, including the 1918 influenza pandemic. During the first year of the COVID-19 pandemic, over 600,000 Americans received convalescent plasma, saving tens of thousands of lives. In 2023, it was also used during the West Nile virus outbreak in Israel, showing promising results.
Past outbreaks of hantavirus and Ebola virus saw the use of convalescent plasma, although with limited success. Effective use hinges on early administration and sufficient antibody levels. Historically, establishing its efficacy proved challenging due to emergency conditions and brief outbreaks. The COVID-19 pandemic provided a longer timeline for conducting clinical trials. Initial studies in other countries misjudged its efficacy due to administration at late stages of disease. Later trials confirmed its benefits when used early and with adequate antibody levels. This positioned convalescent plasma as a verified therapy.
In 2024, the FDA licensed COVID-19 convalescent plasma for immunosuppressed patients, making it the sole antibody therapy available for COVID. Despite its benefits, medical professionals often overlook convalescent plasma. Concerns about utilization in resource-limited areas and antibody standardization persist. However, over 50 countries, including some less developed, used it against COVID. It is possible to standardize units by measuring antibody content.
The reluctance to embrace this therapy may arise from its historical origins or unfamiliarity due to its sporadic use in disease emergencies. Physicians familiarizing themselves with robust evidence from the COVID-19 response might appreciate its potential. Convalescent plasma functions as a public good, relying on donors, public health initiatives, and willing physicians.
For successful deployment, government health agencies must manage the logistics of collecting, testing, and delivering plasma. The FDA’s intervention during the COVID-19 pandemic serves as an example, saving many lives. Physicians must use convalescent plasma early in the disease course for the best outcomes, as late administration limits its effectiveness. In COVID-19, outpatient use significantly lowered the risk of hospitalization.
Public health authorities can locate survivors, encourage plasma donation, and test for antibodies against hantavirus and Ebola. One donation can benefit three patients. These plasma units can be frozen for future use, offering interim therapy until vaccines and antiviral drugs become available.
Arturo Casadevall, M.D., Ph.D., serves as a professor and chair of Molecular Microbiology and Immunology at Johns Hopkins School of Public Health. In 2020, he played a crucial role in deploying convalescent plasma for COVID-19, authoring over 100 related papers.