A century-old approach for fighting infections offers hope as people wait for drugs and vaccines to thwart the coronavirus disease
As cases continue to spike globally, scientists are showing renewed interest in a treatment with ancient roots and many modern applications: convalescent plasma therapy. If it works, the blood of Covid-19 survivors would be used to protect frontliners and prevent patients from getting
The therapy is based on a medical concept called ‘passive immunity.’ Blood from people 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 witnessed significant improvement on their clinical symptoms, and the viral load was undetectable in seven patients who had previous viremia. No
severe adverse effects were also observed.
The researchers have 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.)
But the key advantage to this method is that it’s available immediately, whereas drugs and vaccines take months or years to develop. Infusing blood in this way seems to be relatively safe, provided that 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.
Other countries like India, Turkey, Iran, South Korea, Philippines, and the US have authorized its physicians to experiment with the strategy to fight the coronavirus disease.
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 back in February. “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
Dr. Thad Hinunangan, a pathology physician at the Philippine General Hospital (PGH), said he is positive this method can be effective in the country.
“We still have a long road ahead of us in combating Covid-19 but the past few days have been a promising start for us,” he told Manila Bulletin Lifestyle. “The 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.”
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. “The PGH team, composed of at least one pathology resident and one medical technologist, will visit you to explain the procedure, conduct an interview, and get consent. We will assess the possible vascular access (usually a vein in the antecubital area). Blood will be extracted via a syringe for serologic tests,” he said.
Donors must also have tested negative twice for the virus and have had no mild symptoms for 14 days. People who qualify will then be sent to Paz Mendoza Hall at UP Manila to donate plasma.
The procedure, called apheresis, is similar to giving blood, except that the blood drawn from the patient is run through a machine to extract the plasma, and the red and white cells are then returned to the donor.
Needles go into both arms: Blood flows out of one arm, passes through the machine, and goes back into the other arm. The process usually takes 60 to 65 minutes, and can yield enough plasma to treat three patients, Dr. Hinunangan said.
“To prepare, be well rested and well hydrated. Wear comfortable clothing. Shower and wash the antecubital area. You may ask one person to accompany you,” he added.
Covid-19 survivors who wish to donate their blood may contact the following:
● Philippine General Hospital (Dr. Sandy Maganito): 0917 805 3207
● St. Luke’s Medical Center: 8 789 7700 (local 2096)