What is COVID-19?

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which originated in Wuhan, China, has become a major concern all over the world. The pneumonia induced by the SARS-CoV-2 is named coronavirus disease 2019 (COVID-19). 

The COVID-19 effect

By mid ofthe April, 2020, this virus has affected more than 2,258,725people worldwide and caused more than 154,381 deaths.

The COVID-19 treatment approaches

No drugs or biologics have been proven to be effective for the prevention or treatment of COVID-19. Number of antiviral agents, immunotherapies, and vaccines are being investigated and developed as potential therapies. Apart from this supportive care, such as oxygen supply in mild cases and extracorporeal membrane oxygenation for the critically ill patients. specific drugs for this disease are still being researched. 

All about Convalescent Plasma

Convalescent plasma (CP) therapy, a classic adaptive immunotherapy, has been applied to the prevention and treatment of many infectious diseases for more than one century. Over the past two decades, CP therapy was successfully used in the treatment of SARS, MERS, and 2009 H1N1 pandemic with satisfactory efficacy and safety.

Convalescent plasma refers to the liquid part of the blood from recovered COVID-19 patients. So in this therapy, blood from recovered patients, which is rich with antibodies, used to treat other sick people.

How the therapy works

In this therapy, blood is drawn from a person who has recovered from COVID-19 sickness. The serum is separated and screened for virus-neutralizing antibodies. The serum, which is rich in antibodies, is then administered to a COVID-19 patient showing severe symptoms.

The process for donating plasma is similar to donating blood and takes about an hour, according to Houston Methodist, which became the first academic medical centre in the US to transfuse donated plasma from a recovered COVID-19 patient into a critically ill patient.

Plasma donors are hooked up to a small device that removes plasma while simultaneously returning red blood cells to their bodies. 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, it said.

This therapy is not simple to harness, primarily due to the difficulty of obtaining significant amounts of plasma from survivors. In diseases like COVID-19, where most of the patients with severe symptoms are aged, and often suffer from other medical conditions such as hypertension, diabetes, and so on, the effectiveness remains questionable.

Effectiveness of the therapy

Earlier, a study in China found the therapy effective, albeit on small sample size, in treating coronavirus patients. In this trial, a 200 ml dose of convalescent plasma was administered to 10 adult COVID-19 patients with severe symptoms. The patients witnessed significant improvement with the disappearance of the virus reported among seven patients without any severe adverse side-effects.

Through this therapy, the sick acquires only temporary passive immunization. It lasts only till the time the injected antibodies remain in the bloodstream—usually less than a week. On the other hand, a vaccine, if developed, could provide life-long immunity against the pathogen.

The good news is three critically ill COVID-19 Indian-American patients in Houston are also showing signs of recovery after they were transfused with the blood plasma from recovered patients.

As the world waits for a vaccine against COVID-19 with bated breath, it remains to be seen if this method can provide a much-needed short-cut in finding a cure.

References:

1. Casadevall A, Pirofski L. The convalescent sera option for containing COVID-19. J Clin Invest, 10.1172/JCI138003.
2. Bloch EM, et al. Deployment of convalescent plasma for the prevention and treatment of COVID-19, J Clin Invest, 10.1172/JCI138745.
3. Shen C, Wang Z, Zhao F et al. Treatment of 5 critically ill patients with COVID-19 with convalescent plasma. JAMA, doi:10.1001/jama.2020.4783.

4. Dean  CL, Hooper  JW, Dye  JM,  et al.  Characterization of Ebola convalescent plasma donor immune response and psoralen treated plasma in the United States. Transfusion. 2020. doi:1111/trf.15739.