Updated: March 30, 2020 11:28:00 am
On Saturday, the Houston Methodist Hospital took blood from a patient who had recovered from COVID-19 two weeks ago, and infused it into another critically ill patient. It was a first for the US; the hospital’s blood bank now plans to collect blood from at least 250 recovered COVID-19 patients.
With no specific treatment available for novel coronavirus disease and a vaccine at least a year away, the US Food and Drug Administration (FDA) last week approved use of blood plasma from recovered patients to treat severely critical COVID-19 patients.
How does this therapy work?
It is called convalescent plasma therapy. It seeks to make use of the antibodies developed in the recovered patient against the coronavirus. The whole blood or plasma from such people is taken, and the plasma is then injected in critically ill patients so that the antibodies are transferred and boost their fight against the virus. New York Governor Andrew Cuomo announced on March 24 that the state would begin clinical trials to use plasma therapy for COVID-19 patients. A study in The Lancet Infectious Diseases last month said a COVID-19 patient usually develops primary immunity against the virus in 10-14 days. Therefore, if the plasma is injected at an early stage, it can possibly help fight the virus and prevent severe illness.
How often has it been used in the past?
Several times. The United States used plasma of recovered patients to treat patients of Spanish flu (1918-1920). Hong Kong used it to treat SARS patients in 2005. In 2009, H1N1 patients were treated with plasma. A study in Oxford University’s journal Clinical Infectious Diseases found that “convalescent plasma reduced respiratory tract viral load, serum cytokine response, and mortality” in H1N1 patients.
In 2014, the World Health Organization released guidelines to treat Ebola patients with convalescent whole blood and plasma. The WHO observed that “convalescent plasma has been used successfully for the treatment of a variety of infectious agents” for which no treatment is available. The Democratic Republic of Congo and Guinea eventually did so. In 2015, plasma was used for treating MERS patients.
How is it done?
The process to infuse plasma in a patient can be completed quickly. It only requires standard blood collection practices, and extraction of plasma.
If whole blood is donated (350-450 ml), a blood fractionation process is used to separate the plasma. Otherwise, a special machine called aphaeresis machine can be used to extract the plasma directly from the donor. While blood is indeed extracted from the donor, the aphaeresis machine separates and extracts the plasma using a plasma kit, and the remaining blood components are returned into the donor’s body.
WHO guidelines in 2014 mandate a donor’s permission before extracting plasma. Plasma from only recovered patients must be taken, and donation must be done from people not infected with HIV, hepatitis, syphilis, or any infectious disease. If whole blood is collected, the plasma is separated by sedimentation or centrifugation, then injected in the patient. If plasma needs to be collected again from the same person, it must be done after 12 weeks of the first donation for males and 16 weeks for females, the WHO guidelines state.
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How optimistic is the latest move?
COVID-19 does not have a specific treatment, only supportive care— including antiviral drugs, oxygen supply in mild cases and extracorporeal membrane oxygenation. Dr C E Eapen of the hepatology department of Christian Medical College, Mumbai, who works on plasma exchange in critical patients, said plasma can be infused into two kinds of COVID-19 patients— those with a severe illness, or individuals at a higher risk of getting the virus. Eapen added, however, that while plasma transfers immunity from one person to another, it is not known if it can save lives in COVID-19 infection.
Dr Om Srivastava, infectious disease expert in Jaslok Hospital, agreed: “With antibodies from recovered patients, we try to make sure the person’s infection does not go out of control. It helps, but to what extent we don’t know yet.”
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Can it be done in India?
India has facilities for removing 500 ml of plasma from a donor using aphaeresis.
For this experimental therapy to be tried out, the Drug Controller General of India will first have to grant blood banks approval for removal of plasma from recovered COVID-19 patients. Dr Manoj Chugh, chief scientist in Transasia Biomedicals, said the treatment could be effective for patients in the age group 40-60, but may be less effective for people aged beyond 60 years.
Chugh said the procedure is simple and can be done in India, but it is important to control the risk of infection during transfusion, and the patient’s acceptance is required. “It’s like a vaccine. It will engulf the virus and kill it. But it is easier said than done. We may need a series of approvals. India has never done this before,” he said.
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