Last Updated on August 24, 2020 by Sagar Aryal
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Today, the world is still under the threat of pandemic COVID-19. Different countries are in an attempt in order to find the cure and treatment of it. To date (August 22, 2020) though different countries have been preparing the vaccines which are under the various trials and phases, it has not been officially approved. So, till then, we are here with the concept of Convalescent Plasma Therapy for the treatment of COVID-19 viral infection.
Convalescent= Any person who was previously infected but now has been recovered from it.
Plasma = It is one of the component of blood which constitutes about 55 % of blood. The rest of the 45 % of blood is made up of the Red Blood Cell (RBC), White Blood Cell (WBC), and Platelets. Plasma is a pale yellowish liquid portion of blood.
Figure: Use of Convalescent Plasma to Treat COVID-19 Patients.
What is done in Convalescent Plasma Therapy?
In this therapy, any person who was previously infected with COVID-19 viral infection but now has been recovered from it can donate the plasma who is suffering from the active case of COVID-19.
Why do we take plasma, not the other components?
It is because plasma contains the antibody. The main purpose of transferring the plasma is to transfer the antibody from the donor to recipient. Antibody IgM and IgG are transferred.
What is the purpose of transferring such Antibodies?
The antibody is immunoglobulin which is a protein. When the Antigens like bacteria and viruses enter the human body our immune system which works like the defense system takes action in it. The Y-shaped antibody encounters the antigens so that the foreign invaders can be eliminated from the body and we can be healthy. Here, as this virus is new, only those who have encountered the virus, their body will produce the antibody against it and such antibodies will be present in their’s blood for future purposes. If in the future, they encounter the same virus then the already formed antibody will immediately take action and protect them. So, in this therapy, the formed antibody is transferred to the patient who might be in the ventilator or whose immune system is not strong enough to cope with the virus-producing sufficient antibodies.
What is the name of this process?
It is called Plasmapheresis. In this blood like as in the blood donation, blood is collected but the difference is the automated function extract the plasma and other blood cells components and platelets everything gets returned to your body.
Who is eligible for plasma donation?
Should have 2 weeks of recovery
Must be healthy
Haemoglobin, protein, age, weight, etc and other parameters are checked on the basis of protocol
Screening is done to ensure the prevention of HIV, Hepatitis, etc diseases
Patients eligibility (Recipient)
Lab confirmed COVID-19
Dyspnea (difficulty in breathing)
Respiratory frequency ≥ 30/min
Blood oxygen saturation ≤93 %
Other parameters are also checked according to the protocol
Is this therapy reliable?
Yes, this is not any therapy that has been suddenly invented. Before, 100 years ago, Emil Von Behring got Nobel prizes in Physiology and Medicine.
It was used for the treatment of diphtheriae.
It was used previously in the treatment of SARS, MERS, Ebola virus, Spanish flue, etc, and was found to be effective too.
Is this therapy the permanent solution? Why prepare the vaccine, if it’s reliable?
It is because the vaccine is active immunization whereas this therapy falls under passive immunization.
In the active immunization, the immune system of the body produces the antibody itself which is longlasting.
In the passive immunization, the preformed antibody is transferred which is not long-lasting.
Passive immunization is used in the case of Diphtheria, Tetanus, and Botulism for the neutralization of toxins.
Similarly, passive antibodies are also used for viruses like Rabies, Hepatitis A, Hepatitis B, etc.
In the developing countries, the ventilators are not present in a sufficient amount. Along with the COVID-19, there are still the patients who are immunocompromised and been effected with other illnesses too. In such a case, if COVID-19 patients could be treated with this therapy, such ventilators won’t be pre-occupied.
This therapy was first used for COVID-19 patients in China. Later other countries like United States, United Kingdom, India are using this therapy for the treatment.
According to the research done in Shenzhen, China Convalescent Plasma Therapy was found to be effective in 7 out of 10 patients.
Challenges for Convalescent Plasma Therapy
It is a slow process.
In comparison to the active cases, only a few donors are willing to donate the plasma.
They think themselves as they will get weak if they donate it.
Weakness after the plasma donation is Myth or Reality?
The doctor suggests that it is just a myth. A healthy convalescent person can donate plasma twice a month. About 200 ml of plasma donated can be helpful for saving the life of people in ventilator.
Plasma collected at a time can be used up to 2 doses.
People age 18-50 years, whose weight is 45-55 kg or above can donate it.
Normally, blood present in the body is :
66ml/kg body weight in female
76ml/kg body weight in male
350 ml from the age group 44-55 kg
450 ml from the age group above 55 kg
So, extra blood present in the human body will be about:
16ml/kg in female
26ml/kg in male
In about 24-48 hr new plasma will be formed.
So, doctors suggest that the fear of weakness is only the myth.
Transfusion-related Immunological Reactions
Unanswered questions (Research going on )
Though this therapy can be boon for immunocompromised persons, diabetic patients, heart patients not to worsen the condition, it is still not sure what is the appropriate dose of plasma which will totally cure the particular person. According to the severity and the person’s immune response, plasma dose may be varied.
What will be the life span of the memory cells? Few months or years?
Some researchers suggest that Monoclonal Hybridoma Technology can be used for the production of antibodies in the large amount.