Prospects of Plasma Therapy for COVID-19 patients

 

 

 

 

Prospects of Plasma Therapy for COVID-19 patients :

 

 

In the  absence of a vaccine (during 2020 ) or any specific antiviral medications for the treatment of COVID-19, convalescent plasma therapy is being seen as a promising therapeutic option.

 

What is plasma therapy? It is an experimental procedure for COVID-19 patients. In this therapy, plasma from a COVID-19 patient, who has recovered from the disease, is transfused into a critically affected COVID-19 patient. The therapy can also be used to immunise those at a high risk of contracting the virus, such as health workers, families of the patients and other high-risk contacts.

The plasma from the recovered patient is called convalescent plasma and the treatment is known as convalescent plasma therapy (CPT). Plasma is the (yellowish) liquid part of blood and constitutes about 55 per cent of the total blood volume. It has high concentration of neutralising antibodies that fight infections caused by bacteria and viruses. The concept behind the therapy is simple and is based on the premise that the plasma of a patient who has recovered from COVID-19 contains antibodies with the specific ability to fight the novel coronavirus. When it is transfused into a critically ill COVID-19 patient, it will start targeting and fighting the virus.

The concept behind the therapy is simple and is based on the premise that the plasma of a patient who has recovered from COVID-19 contains antibodies with the specific ability to fight the novel coronavirus. When it is transfused into a critically ill COVID-19 patient, it will start targeting and fighting the virus

 

How plasma is donated? The process of donating plasma is similar to routine blood donation. A small device is attached to the donor in which a tube of fresh blood drawn from him is made to spin using a centrifuge until the red blood cells fall to the bottom of the tube.

The blood plasma is then drawn off and the red blood cells are simultaneously returned to the donor. The whole process takes about an hour. Unlike regular blood donation, in which donors have to wait for red blood cells to replenish between donations, plasma can be donated more frequently, as often as twice a week. A single donor can donate 400 ml of plasma. Hence, plasma from a person who has recovered from COVID-19 can help two COVID-19 patients to recover as 200 ml is sufficient to treat one person

 

T he plasma therapy was discovered by a German physiologist, Emil von Behring, in 1890. He found that the serum (plasma without clotting factors) obtained from a rabbit infected with diphtheria was effective in preventing diphtheria infection. Behring was awarded the first-ever Nobel Prize in Physiology or Medicine in 1901. Since 1892 till the development of effective antimicrobial therapy, serum therapy was used effectively to treat many bacterial (e.g., diphtheria, pneumococcus, meningococcus) and some viral (e.g., measles, mumps, etc.) infections. Serum therapy was used to advantage to treat contact infection disease – pertussis – until about 1970. Also, horse serum was used to treat tetanus until the 1970s

 

During the avian-borne flu, called Spanish flu that resulted in 50 million deaths worldwide, plasma therapy was used to save lives. This flu was first observed in 1918 in Europe, the United States and parts of Asia and then it swiftly spread around the world (the pandemic did not originate in Spain, but Spain during World War I being neutral did not impose press censorship, and a report of the 1918 flu in a Spanish press led to the pandemic being called “Spanish flu”). In the 1920s, plasma therapy was used to treat scarlet fever and in the 1930s, doctors like J. Roswell Gallagher effectively used the therapy against measles.

 

 By the 1940s and 1950s, antibodies and vaccines began to replace the use of plasma therapy for treating any infectious disease outbreaks, but the old-fashioned methods came in handy yet again during the Korean War, which started in June 1950. During the war, thousands of United Nations troops were struck with the so-called Korean haemorrhagic fever caused by a virus known as hantavirus. With no other treatment available, field doctors transferred plasma to sickened patients and saved umpteen numbers of lives. Plasma therapy was also deployed against 21st century outbreaks of SARS, H1N1, MERS and Ebola – all novel viruses that spread through communities with no natural immunity, no vaccine, and no effective antiviral treatment.

 

 In 2014, the WHO had recommended the use of plasma therapy to treat patients with the antibodyrich plasma of those who had recovered from the Ebola virus disease (EVD). Today, the best treatment for Ebola is still a pair of “monoclonal antibodies”— individual antibodies isolated from plasma and then cloned artificially in a lab.

 

 

 

Issues and risk factors

According to doctors and researchers, the foremost consideration for plasma therapy to be effective is that the plasma should contain sufficient antibodies against the infection the recipient is suffering from. The antibody titre is a test that detects the presence and measures the amount of antibodies within a person's blood and can be used to detect the presence and measure the amount of antibodies within a person’s plasma. In a recent study made by Arturo Casadevall and Liise-anne Pirofski that appeared in the 1 April 2020 issue of Journal of Clinical Investigation, the authors write that for effective therapy “a sufficient amount of antibody must be administered when given to a susceptible person; this antibody will circulate in the blood, reach tissues, and provide protection against infection. Depending on the antibody amount and composition, the protection conferred by the transferred immunoglobulin (antibody) can last for weeks to months.” As with routine blood donation, the blood from the cured patients of COVID-19 is screened for the presence of any disease-causing agents, such as Hepatitis-B, Hepatitis-C, HIV, malarial parasite, and so on. Although the proper screening of blood can eliminate transfer of blood-borne infections, transfer-related reactions, including immunological reactions, such as serum sickness and allergic reactions can also pose threat to the recipient. In a study conducted at the Johns Hopkins University immunologists have stated some other potential risk factors. According to them, the antibody administration may end up suppressing the recipient’s natural immune response, leaving the patient vulnerable to subsequent re-infection. But the biggest

 

Risk factor is that the therapy might fail for some patients and can result in an enhanced form of the infection as has actually been observed in the case of dengue virus. So, plasma therapy does not seem to be a fool-proof therapy as many issues and risk factors are involved in the administration of this therapy to critically ill COVID-19 patients. The results of trials from five states approved by ICMR on potential use of plasma therapy on critically ill patients of COVID-19 are yet to come. In the meantime, the All India Institute of Medical Sciences (AIIMS) is planning to conduct a clinical trial on the efficacy of CPT in the treatment of COVID-19 patients and necessary approvals are being taken from the Drug Controller General of India (DCGI).