Convalescent Plasma

What is convalescent plasma and how can it help someone with COVID-19?

Most bacterial infections can be treated effectively by antibiotics, but these drugs are not effective in most viral infections. To be sure, anti-viral therapy can help control diseases caused by certain viruses.  For example, antiretroviral drugs such as AZT are beneficial to those infected by HIV.  Anti-influenza drugs such as Tamiflu can reduce the severity of disease caused by Influenza virus.  Acyclovir is used to control the symptoms of herpes simplex (“cold sores” and “genital herpes”) and herpes zoster (“shingles”).  But unfortunately, most viruses cannot be cleared by drugs.

Ebola is an example of a virus for which there is no effective drug therapy.  Endemic in west Africa, Ebola virus disease (EVD) has a death rate of about 50%.  Without an effective drug to treat Ebola infections, doctors treating EVD had little to offer.  Several years ago, researchers hypothesized that there might be something in the blood of patients who survived Ebola virus infection that could help patients with EVD.  Sure enough, patients who received plasma donated by people who had survived Ebola had a small but significant reduction in deaths compared to those who did not.

Why did this work?

The theory is that Ebola virus disease survivors form antibodies that help their bodies fight the infection.  These antibodies persist in the plasma (the liquid part of blood) of survivors for a long time after infection, and these antibodies are transferred to the patient through a plasma transfusion.  But this is just a theory.  Although there are lots of reasons to believe this theory is true, it has not yet been proven.  As I am writing, convalescent plasma transfusions are experimental.  

Early in the COVID-19 pandemic, doctors found themselves in a similar situation.  Without an effective drug therapy, many began to use convalescent plasma as an alternative, but unproven treatment for serious disease.  In early April, the U.S. government announced a partnership with the Mayo Clinic to facilitate availability of convalescent plasma to COVID-19 patients in an unprecedented nationwide experimental program.  The project, known as US COVID Plasma, enrolled more than 100,000 patients.  Although it will take years to fully analyze the data collected, initial results are overwhelmingly positive.  In patients with serious COVID-19, the transfusion of convalescent plasma is associated with a 37% reduction in mortality.  On August 23, the FDA announced an emergency use authorization (EUA) for convalescent plasma, making the treatment available to patients not enrolled in a study.  Convalescent plasma has become one of the most important therapies available to treat life-threatening COVID-19.  My colleagues believe it has saved countless lives.  So do I.

Patients who have recovered from COVID-19 can help others who are sick with a simple plasma donation.  In fact, each plasma donation can be divided into four doses, potentially helping four people currently suffering from the disease.  If you have tested positive for SARS-CoV-2, please consider donating at your local blood center.  You’ll be someone’s hero.