Imagine you cough up to the doctor and get a blood transfusion from a goat. It probably sounds strange today, but that’s exactly how anti-antiepileptic therapy began in the late 1800s.
Researchers have found that plasma, the part of blood that is left when you release the cells, has healing properties. In fact, the first Nobel Prize in Physiology or Medicine was awarded in 1901 to Emil von Behring for his work on this approach to treating diphtheria.
Nowadays, scientists understand healing properties of plasma come from antibodies, which are proteins in the blood that foreign invaders recognize and destroy. The purpose of a vaccine is to induce the body to make more of these protective antibodies, and to reduce the severity of the infection or prevent it all together. While Americans are waiting for a COVID-19 vaccine, antibody therapy offers a potentially effective treatment option – but one that further study warns.
As a physician-scientist in medicine for pulmonary and critical care, I care for patients with lung disease and those who are critically ill in the intensive care unit. I also study the role of antibodies and the cells that make them, called B cells, in lung disease. So when the worst public health crisis in a hundred years struck in my first year of training, like many of my colleagues, I saw it as a call to arms. This is why we became doctors.
The most efficient laboratory – your own immune system
Since von Behring’s pioneering work, antibodies have been used to treat a variety of different infections. This approach declined with the advent of antibiotics in the 1930s.
In the case of epidemics of new infections, antibodies have been re-introduced as a therapeutic in part because of one factor: time. Developing a medicine in the laboratory takes a long time. In the case of antibodies, the human immune system does this for us. Our bodies are equipped with an astonishing repertoire of B cells capable of making up to one quadrillion different antibodies.
Each of these antibodies can recognize different parts of an infection. When a B cell recognizes a virus like SARS-CoV-2, which causes COVID-19, as foreign, that B cell makes antibodies that then float in the blood, binding to the viruses and protecting us from infection.
Three to four weeks after a person recovers from the infection, doctors can harvest these antibodies into what is known as convalescent plasma. If effective, this provides a rapid trace after treatment.
Chance in crisis
Convalescent plasma has been tested in recent epidemics such as SARS, MERS and Ebola. In any case, there has been at least some evidence that the treatment is safe and effective.
Fortunately for humans, these outbreaks have been relatively limited in scope, and prevent the kinds of numbers needed in clinical studies to show that a treatment works. The COVID-19 pandemic, as devastating as it has been, provides a unique opportunity to study whether plasma recovery is effective.
The pandemic was an opportunity to do important work to understand the biology of the disease and how to treat it. I am now assisting in the determination and conducting of an experiment testing the effect of convalescent plasma in COVID-19 patients.
In our trial, my colleagues and I targeted patients who were hospitalized but not yet critically ill. We hope to test whether convalescent plasma can prevent the progression of this disease to critical illness and death. Entering the sixth month of this pandemic, we have now enrolled patients for the trial and our analysis is underway.
Hopefully, the trial in the coming months will help determine if convalescent plasma is an effective treatment for some patients with COVID-19. Importantly, we will not only evaluate the clinical outcomes, but we will also study the immune system’s responses to plasma recovery so that we can better understand the underlying mechanisms by which the disease is affected.
Early studies show promise
Several studies have already shown promise for convalescent plasma in COVID-19. A retrospective study by researchers in New York and a prospective study from Houston suggest that convalescent plasma can be effective, especially if given early before the patient sits on a ventilator. In addition, in a recent report from the Extended Plasma Recovery Access Program, an analysis of more than 35,000 transfused patients showed that previous transfusions with higher concentrations of antibodies were associated with improved outcomes.
[Deep knowledge, daily. Sign up for The Conversation’s newsletter.]Convalescent plasma is also the foundation on which specific anti-body therapy is based. In specific antibody therapy, the specific neutralizing antibodies present in recovery time plasma that binds to the virus are isolated and then synthesized in the lab. This has been shown to be effective in the case of Ebola. Researchers have now isolated these neutralizing antibodies to COVID-19, and clinical trials are underway to test their effectiveness as well.
These studies and ours provide important steps in the development of therapeutics. But even during the urgency of a pandemic, it is critically important to conduct large, randomized phase 3 clinical trials before changing clinical practice. To support this, the Food and Drug Administration recently withdrew its authorization for emergency use of convalescent plasma, citing a lack of strong evidence. Only by following these strict standards of evidence can we finally answer the question: Does convalescent plasma work? In this case, no goat blood is required.
This article has been republished from The Conversation, a nonprofit news website dedicated to sharing ideas from academic experts.
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Jeffrey M. Sturek does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has not disclosed any relevant relationships beyond its academic designation.
