While still unproven and experimental, the use of donated blood has potential to treat patients with serious or immediately life-threatening coronavirus infections.
“Convalescent plasma” is obtained from individuals who were infected with COVID-19, but are now recovered and have antibodies to the disease in their blood. Clinical trials are currently underway to evaluate the safety and efficacy of using convalescent plasma, but as there is no known cure for the disease, the US Food and Drug Administration (FDA) is permitting healthcare providers to use it under an emergency investigational new drug (eIND) application. The FDA has also issued guidance on its use.
What does the research show?
The results of a study, published in the Journal of the American Medical Association, are encouraging, but cannot be considered definitive. Convalescent plasma was given to five critically ill COVID-19 patients in China with acute respiratory distress syndrome, who received mechanical ventilation at the time of treatment. Their symptoms improved within about a week of treatment, and viral loads decreased and became negative within 12 days.
A second study, published in the Proceedings of the National Academy of of Sciences of the United States of America (PNAS), treated 10 patients with a single transfusion of convalescent plasma. Clinical symptoms significantly improved within three days, and the viral load became undetectable in seven patients.
What can we learn from history?
The idea of using convalescent blood products (CBP) for passive immunization – to both prevent and treat infectious diseases – is an old concept that dates back to the late 19th century, when it was first used to treat diphtheria. Studies conducted during the Spanish influenza pandemic of 1918 to 1920 suggested CBP could be a viable treatment. In the decades that followed, it was used to treat a wide variety of other viral infections, including measles, Argentine hemorrhagic fever, influenza, Middle East respiratory syndrome coronavirus (MERS-CoV), H1N1 and severe acute respiratory infections.
What can healthcare providers expect?
Aside from the fact that its efficacy is uncertain, other treatments will be needed for COVID-19 infections, as convalescent plasma is labor intensive to obtain and limited by the availability of donors. In the meantime, a group of physicians and scientists have formed the National COVID-19 Convalescent Plasma Project to investigate the use of convalescent plasma in the current COVID-19 pandemic.
- Treatment of 5 Critically Ill Patients With COVID-19 With Convalescent Plasma, JAMA.
- Effectiveness of convalescent plasma therapy in severe COVID-19 patients, Proceedings of the National Academy of of Sciences of the United States of America.
- Convalescent plasma: new evidence for an old therapeutic tool?, NCBI.