Blood (technically known as Whole Blood) contains mainly four components viz., Plasma, Red Blood Corpuscles, White Blood Corpuscles and Platelets. Plasma is the liquid portion of the blood and is a yellowish liquid. Plasma is a mixture of water, sugar, fat, protein, and salts. The main job of the plasma is to transport blood cells throughout our body along with nutrients, waste products, antibodies, clotting proteins, chemical messengers such as hormones, and proteins that help maintain the body’s fluid balance.
Plasma Therapy involves extracting the blood plasma of a person who has recovered from an infection and transfusing the blood plasma to a person who is still sick with the infection. Plasma Therapy is more than 100 years old and has been widely used in treating patients in various flu outbreaks in the past. It was used about a 100 years ago during the Spanish Flu and more recently in Ebola, SARS, MERS outbreak. It is very useful for infections from bacteria and viruses which do not have a cure or vaccine yet.
The blood of any person, once infected by a virus (or in fact any infection), develops antibodies to combat the infection. When the rate of such development of antibodies is higher than that required to fight the viral load or the viral population, the antibodies are effective in combating the infection and the patient recovers. Conversely, if the blood is not able to develop antibodies fast enough, the patient condition could become critical and ultimately may result in a fatal incident. The plasma of patients who have recovered from the infection contains antibodies that can effectively combat the infection. Such antibodies, when transferred from a recovered patient to a sick patient through plasma transfer, help the sick patient to recover faster.
Since Covid-19 does not yet have a proven vaccine or a cure, medical practitioners all over the world have been using Plasma Therapy on Covid patients. Covid Convalescent Plasma Therapy involves transferring plasma recovered from Covid patients who have recovered from the Covid19 infection to patients still sick with the infection.
The medical fraternity is yet to converge on several aspects of Plasma Therapy for Covid-19; hence it is still considered as a trial therapy. However, there is adequate empirical evidence to support the benefits of Plasma Therapy on Covid patients as the recovery rates have improved significantly in many cases. For Covid-19 infection Plasma Therapy has been found very effective for patients in pre ventilator stage. You could also refer to this study by Mayo Clinic
The procedure for separating plasma from other blood components is called apheresis. This process is carried out under medical supervision of a Haematologist. When a donor volunteers for plasma donation, before plasma is withdrawn, three things are important
During apheresis, a blood stream is drawn from the donor and circulated through an apheresis machine. Inside the apheresis machine, plasma is separated from blood and the rest of the blood components viz., platelets, red and white blood corpuscles are returned back to the donor through intravenous fluids. Today, apheresis machines are available at several Hospitals/Blood Banks. Some hospitals do it manually through centrifuging the blood but this is not recommended by experts due to various complexities.
While most plasma donors do not experience any discomfort while donating plasma, very few donors may experience dehydration, dizziness, fatigue and discomfort. But plasma donation is done under adequate medical care and supervision. As such plasma donation today does not carry significant risks.
Any transfer of body fluids from one person to another entails risks of infection which were unknown and undetected in the donor. When adequate precautions are taken, the benefits of plasma transfer for Covid-19 patients far outweigh the risks and hence plasma transfer is being adopted by medical practitioners all over the world till a cure or a vaccine is available for Covid-19.
Plasma donation is a humanitarian act. A Covid-19 recovered person has the opportunity to save someone’s life.
How soon can a plasma donor return to normal life after donating plasma?
Plasma donation is a painless procedure and the plasma donor can also almost walk back to normal life from the hospital. This is because the main oxygen carrying capacity of the blood remains unaffected by donation of plasma.
Usually about 500-600 ml of plasma is drawn from a donor at a time. This is usually administered to 2-3 doses of 200-250 ml either to a single patient or to multiple patients.
Plasma donation requires more medical supervision than blood donation. However plasma donors can rebuild the lost plasma much faster than blood donors can rebuild the lost blood. More plasma can usually be drawn from a plasma donor than blood from a blood donor.
Since the donor has developed antibodies, there will not be any significant risk of getting symptoms or getting affected.
No. In an overwhelming majority of upto 90% of cases, Covid-19 patients recover on their own and even hospitalization is not required. Such patients develop antibodies on their own. It is required for people who are for some reason not able to develop their own antibodies.
Once a patient is in the hospital/blood bank and after the counselling and verification of medical history is over, the process usually takes about 90 – 120 minutes.
No. All Blood Banks/Hospitals are not equipped with all the facilities. Any Blood Bank/Hospital that has apheresis machine and has a license to draw plasma can collect plasma. Also, plasma donation has to be conducted under the supervision of a Haematologist.
There are several criteria that doctors apply to check the eligibility of patients. However the major criteria are follows:
No. Provided the conditions for donor eligibility are met, an average human body has 5 litres of blood. Only 400-500 ml of plasma is drawn. The plasma along with the antibodies is made up again in 48 hours.
Even if a donor does not donate, the antibodies decrease over the next 8-10 weeks. Human body has memory B cells (white cells) which respond and produce antibodies. For Covid recovered donors, the B cells learn how to make the antibodies and in case of re-infection they respond very quickly to produce the antibodies to fight the virus.
The antibodies levels in the plasma tend to drop off after 60 days after recovery. Each donor can donate plasma 2-3 times between 14th day and 60th day after recovery; each time with a gap of minimum 14 days.
For any drug or a treatment protocol to get approvals for extensive use, regulators all over the world require that the drug or the protocol should be proven in under a wide variety of controlled conditions and lot of statistical evidence is required to prove the efficacy of the drug/protocol. Such evidence also includes monitoring such patients for after effects/side effects for a reasonably long period after being subject to such drug or protocol. Collecting such huge amount of data takes a lot time and coordinated trials over different patient conditions over a large number of patients, often in multiple geographies to account for different gene-pools. Necessary amount of data is still not available. Hence Plasma Therapy for Covid-19 is still under trial.