Blood of COVID-19 survivors can save lives

Researchers have recently manifested renewed interest in an old medical treatment for modern applications: convalescent plasma therapy. 

Medical professionals are seriously considering using the blood of COVID-19 survivors to protect frontliners and prevent patients from getting seriously ill.

The therapy is based on a medical concept called ‘passive immunity’ – blood from those who have recovered from an infection can be a rich source of antibodies, proteins made by the immune system to attack a pathogen. Infusions of plasma—the clear liquid that remains when blood cells are removed—may increase the patients’ disease-fighting response to a virus, giving their immune systems an important boost. This approach has been used for decades to treat infectious diseases such as Ebola, the Spanish flu, rabies, polio, and SARS.

Preliminary data on a handful of patients in China showed they got better after receiving plasma infusion from survivors, but large-scale clinical trials must be done to prove its effectiveness. In the study, a 200 ml dose of convalescent plasma was administered to 10 adult COVID-19 patients with severe symptoms. The patients improved significantly and the viral load was undetectable in seven patients who had previous viremia. No severe adverse effects were observed.

Researchers also found that, through the 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.)

Key advantage to the method is its availability. Drugs and vaccines take months or years to develop. Infusing blood in this way seems relatively safe, provided it is screened for viruses and other infectious agents. It can also become an alternative treatment for patients in critical condition who do not respond to antiviral drugs, according to Dr. Choi Jun Yong, a researcher at Severance Hospital in Seoul, Korea.

India, Turkey, Iran, South Korea, Philippines and the US have authorized its doctors to experiment with the strategy to fight COVID-19.

A top emergency expert at the World Health Organization (WHO) said later that using the therapy was a “very valid” approach to the test.

“You are essentially giving the new victim’s immune system a boost of antibodies to get them through the very difficult phase, with hope,” Dr. Mike Ryan, head of WHO’s health emergencies program, said. “It must be given at the right time, because it mops up the virus in the system, and it just gives the new patient’s immune system a vital push at the time it needs it.”

Dr. Thad Hinunangan, a pathology physician at the Philippine General Hospital (PGH), said he is positive this method can be effective in the country.

“Transfusion is one of the ways we can help critically ill patients. One donor yields around 500 ml of plasma, and this is divided into two aliquots of 250 ml each and transfused to one patient,” he said.

PGH, followed by St. Luke’s Medical Center, was the first in the country to attempt the treatment, having already given three of its patients the treatment so far.

Prospective donors, Dr. Hinunangan said, will have to first undergo screening to meet strict criteria. Donors must have tested negative twice for the virus and have had no mild symptoms for 14 days.

The procedure, called apheresis, involves blood drawn from the donor and run through a machine to extract the plasma, with the red and white cells returned to the donor. The process usually takes 60 to 65 minutes, and can yield enough plasma to treat two patients.