Treatment of Covid-19 with plasma: "WHO is right to be careful"

Text by: Lina Taghy Follow

8 min

Donald Trump announced, Sunday, August 23, the authorization in the United States of the transfusion of blood plasma from people cured of Covid-19 to hospitalized patients. The American validation of this therapy to fight against the coronavirus comes ahead of the results of clinical trials. Interview with Karine Lacombe, infectious disease specialist and head of department at Saint-Antoine hospital in Paris, who advocates caution.

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RFI: What is the role of plasma in the body?

Karine Lacombe: Plasma is the fluid in which blood cells, such as white blood cells, red blood cells and platelets, bathe. But this fluid also carries a lot of proteins, for example, antibodies which are proteins that help defend against viruses and bacteria. It is an extremely important fluid in the functioning of the body, especially in its fight against infectious diseases. 

Why use plasma to treat Covid-19 ? 

Plasma therapy is a treatment that has been around for an extremely long time and has been used against many other bacterial and especially viral infections. In the context of Covid-19, the idea is to use the passive transfer of immunity: in the plasma, you have these antibodies which, in people who have recovered from the disease, have developed immune defenses. We will collect these antibodies and transfuse them to sick people who have not yet gotten rid of the virus, and therefore who have not developed antibodies, most of the time. The idea of ​​passively transferring these antibodies is to provide immune defenses to sick people. 

What does the treatment consist of ?

The treatment is a collection of plasma. Healed people donate blood and in this donation, platelets, white blood cells, red blood cells are removed and they are returned to the donor. We only keep the plasma, which is then processed. Tests are done: if the plasma is positive for viruses, it is eliminated, otherwise it is kept. It is also subjected to a treatment to eliminate any pathogenic agent, bacterial or viral. The plasma is then conditioned and then frozen. When a person is sick, in this case from Covid-19, the bags of plasma are thawed and they are transfused, like any labile blood product [We call a labile blood product, the product of a donation of blood and intended to be transfused to a patient, editor's note].

Where are the clinical trials at? 

Several clinical trials were initiated between April and May around the world. Currently in France, we are in the process of recruiting, it having been slowed down from May since there have been many fewer cases thanks to confinement. Still in France, for example, when the patient has a pulmonary Covid-19 and less than ten days of symptoms (this is a condition for entering the trial), he begins the therapeutic trial and can either benefit from the plasma, either be in the control group, that is to say a standard treatment without plasma. 
Among the other therapeutic trials that are underway around the world, there are some where we have had preliminary results: some show it works, some show it doesn't work, but for now we don't have no convincing answer yet. The evaluation of the efficacy of the plasma is still in progress.

Why has the United States allowed the expansion of blood plasma transfusion from people recovered from Covid-19 to hospitalized patients ?

In France and the United States, we have what is called compassionate access, that is to say, the possibility of accelerated treatment with plasma. This compassionate access is, however, very limited. In France, we had this authorization in April and we have already transfused plasma to people sick with Covid-19, in particular people who could not develop their own antibodies, because they had hematological diseases, for example. , that they did not have the cells in the body that allow them to develop antibodies, or because they had treatments such as chemotherapy which made them much more fragile in the face of Covid-19. The accelerated marketing authorization, which was granted three days ago by the Federal Drug Administration (FDA) in the United States, follows the first results of efficacy but above all of tolerance, that is to say -to say harmless [which is not toxic, harmful, editor's note]. There are 35,000 people who have been treated in the United States in regulated compassionate access, and the safety of plasma therapy has been demonstrated: there have been no major side effects reported in the context of access. accelerated treatment, so authorization was given last Sunday in the United States for a wider use of plasma therapy in the context of Covid-19. 

What are the risks and possible side effects of this treatment ?

The risks and side effects are the same. The risk of inoculating an infectious agent is almost nil. There are however risks, which we understand very well, which are not necessarily linked to this Covid-19 plasma but which are linked to plasma in general. The first risk is linked to the fact that we bring fluid into the body, and that there may be an overload. For people who have, for example, heart problems, there may be what is called "cardiac overload". This is a risk that we know very well and that we prevent by giving a drug that will make the person to be treated urinate, to allow him to increase his urinary extraction.

The second risk is an allergy risk. There too, like any transfusion of labile blood product, one can have an allergy to the product which is inoculated. It is an extremely low risk but it is not zero. With the American study done on 35,000 patients, we found that there are almost no reported cases of allergy. The potential benefit of this treatment is much greater than the risk of developing heart overload or an allergy. 

Why has the World Health Organization (WHO) been cautious about plasma therapy?

WHO is right to be cautious. We do not yet have results on the effectiveness of this treatment. For the moment it is a treatment which is still being tested. In my opinion, Donald Trump gave an authorization much too early , probably for electoral purposes. He needed to make a major announcement in the area of ​​Covid-19. He has already tried doing it with hydroxychloroquine, and he wants to do it again with plasma. But because of this announcement, we should not think that plasma is the panacea. We don't know yet. Probably the treatment works for some people and probably much less for others. 

The other problem, and I think the WHO had this risk behind it, is that in many countries of the world, especially developing countries, blood safety is not optimal. Under the pretext of treating Covid-19, people should not be exposed to Hepatitis B, Hepatitis C, or HIV. Most of the time, Covid-19 is a mild disease, in 80% of cases it is a disease with few symptoms, and in 15% of cases, there is hospitalization without going through resuscitation, so it should not be not that we end up with cases of transfusion of plasma with HIV to someone who has a mild form of Covid-19. Caution is the best course of action at the moment. 

Our selection on the coronavirus

• Listen to our Coronavirus Info column 

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→  What we know about the mode of contagion
→  Disparities and inequalities in the face of the coronavirus
→  Triple therapy, Discovery… update on research
→  Remdesivir, antibodies and immunity
→  The vaccine race is in full swing
→  How to make a mask and use it well

• Our series  :
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→ "  Words of nurses  "

• After Covid-19, towards a new world?

• See also the records of RFI Knowledge on Covid-19
→  Birth of a pandemic
→  Daily proof
→  The history of epidemics
→  Science facing Covid-19
→  The geopolitical consequences

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