Convalescent Plasma – Hope in the Fight Against COVID-19

Convalescent Plasma – Hope in the Fight Against COVID-19

The immune system has a host of different defense mechanisms that respond when the body is under attack. One such mechanism is the production of antibodies. Antibodies are proteins, also known as immunoglobulins. Antibodies are produced by white blood cells known as plasma B cells and secreted in response when the cell is presented with antigens. Antigens are structures present on pathogens that allow the body to recognize the pathogen as foreign, this recognition causes an immune response that helps to fight the infection. Antigens and antibodies are analogous to a lock and key mechanism, with precision binding of an antigen to a specific antibody. Once bound together, the antibody can label a microbe or an infected cell for attack by other parts of the immune system, or can neutralize its target directly (for example, by inhibiting a part of a microbe that is essential for its invasion and survival). Part of this system is the production of memory cells; these survive in the body for decades after an infection has subsided to allow a more rapid response should you be exposed to the pathogen again at a future time.

Fighting on Foreign Soil

These immune processes mean that if you have been infected with and recovered from COVID-19 your blood plasma will now contain COVID-19 antibodies. These provided one element of protection as you fought off the disease and won. It is then possible that your plasma may be used to help others in their fight against the disease. Once transfused to a patient still fighting the infection, your antibodies can help their immune system to more rapidly and effectively respond by accelerating the time it takes for their immune system to start producing antibodies. The plasma used is referred to as convalescent plasma as it is removed from patients already recovered. Plasma is simply the liquid part of your blood (not the red or white cells or the platelets) and is 91-92% water. Immunity when not acquired by production of your own antibodies is known as passive immunity.

Although this theory holds promise, it is important to remember that as far as COVID-19 is concerned there is much that we still don’t know, including whether our antibody soldiers can fight on foreign soil. That is, will they still be effective in someone else’s body? Historically, the basis for this approach has been used successfully to treat other conditions from SARS, Ebola, H1N1 and even the Spanish flu a hundred years ago. The far-reaching impact of the COVID-19 pandemic and the large number of active infections offers scientists and researchers an opportunity to test the effectiveness of this method with a rigor not previously available. This will provide valuable information to treat not only COVID-19 but future pandemics as well.

Signs of Encouragement

Although it is far too soon to say how effective this may be, given the FDA only initiated the collection of convalescent plasma just over a month ago, there are encouraging signs in the form of anecdotal evidence. One study published in PNAS on the April 28th by Duan et al. showed that “Convalescent plasma therapy was well tolerated and could potentially improve the clinical outcomes through neutralizing viremia in severe COVID-19 cases. The optimal dose and time point, as well as the clinical benefit of convalescent plasma therapy, needs further investigation in larger well-controlled trials.” Viremia being the presence of a virus in the blood. Although as the researchers themselves stated, more research is required before definitive answers can be given, there is reason to hope.

The More the Merrier

It goes without saying that numerous donations of convalescent plasma will mean more opportunities to test how effective a treatment it is. Mount Sinai, in New York, has identified more than a 1000 people considered to be high antibody producers and have thus far given plasma transfusions to over 150 patients. The Red Cross is set to collect donations at more than 170 locations in the US. Although thousands have responded as willing donors, only around 10% meet the eligibility requirements for donation as set out by the FDA. It is critical then that more patients that have recovered are tested for eligibility.

A Simple Process

The process to collect plasma is fairly straight forward and is minimally painful and can be likened to a normal blood donation. After a screening process during which the patient is asked a series of questions regarding their health history, the procedure itself takes between one and a half to two and a half hours. As with a normal donation a phlebotomist inserts a needle into a vein in the patient’s arm. The blood is then drawn into a machine where a centrifuge spins the sample to separate the plasma from the blood cells. The plasma is collected in a separate bag while the remaining blood with a saline solution is returned to the patient via the same needle already inserted. This process of drawing and returning the blood occurs a number of times until a sufficient amount of plasma has been collected. The side effects that patients can expect are similar to those in a normal blood donation and for the most part will be a feeling of slight dizziness. Plasma donated is replenished by the patient’s own body within 24-48 hours. Depending on weight of the donor, a single donation can be used for two to four transfusions to ill patients.

In order to qualify to be a convalescent plasma donor, patients must pass normal blood donation requirements and must be have tested positive for COVID-19 and recovered. Patients are eligible if they have been COVID-19 symptom free for at least 14 days. There are multiple organizations involved in plasma collection. To find the nearest location, patients can go to the Red Cross website ( or the website for the National Covid-19 Convalescent Plasma Project ( Patients who do not qualify for plasma donation may consider a regular blood donation as this can be valuable in assisting patients both with and without COVID-19.


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Article Author
Arthritis National Research Foundation

The Arthritis National Research Foundation's mission is to provide initial research funding to brilliant, investigative scientists with new ideas to cure arthritis and related autoimmune diseases. Writing articles about the patients affected and the science being done to find a cure shows why we need to come together to #CureArthritis!

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