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Manila, Philippines – Doctors have been testing many possible cures for COVID-19, the latest being convalescent plasma therapy, a treatment that uses antibodies from coronavirus survivors to boost the immune system of critically ill patients.
It is one of many treatments that are administered as compassionate care, that is, the use of medications and cures that are still in the testing stages, hoping to alleviate the symptoms of sick people.
In the Philippines, St Luke Medical Center (SMLC) in Bonifacio Global City (BGC) and Quezon City have treated 7 patients with convalescent plasma as of Tuesday, April 14, while the Philippine General Hospital (PGH) has treated 3 patients from April 15.
The two hospital groups continue to ask for plasma donations from survivors to use as treatment for their infected patients. (READ: Pay Forward: Coronavirus Survivors Urge Others Who Recovered to Donate Blood)
What exactly is convalescent plasma therapy and how could it help infected patients recover from the new coronavirus?
What is it?
Convalescent plasma therapy it is a type of passive immunization that involves administering the plasma of a recovered patient to infected patients to boost their immune systems and help their bodies fight disease.
Plasma is the part of the blood That remains when red blood cells, white blood cells, platelets, and other cellular components are removed. Contains water, salts, enzymes, antibodies, and other proteins.
Passive immunization is not new, but it is not as durable as active immunity. In passive immunity, a person receives antibodies instead of abandoning his own immune system to produce them.
Active immunization, on the other hand, is done through infection with disease or vaccination. A person who has been actively immunized can produce the necessary antibodies right away the next time they encounter an illness; this lasts a long time, sometimes for life.
PLASMA. Plasma from a COVID-19 survivor is collected and transfused from an infected patient to boost their immune system. Photo courtesy of St Luke’s BGC Medical Center
Is it a cure for COVID-19?
Convalescent plasma is one of the treatments for COVID-19 that is being evaluated. No treatment or vaccine for the disease has been announced until Tuesday, April 14, according to the World Health Organization (WHO).
The WHO also says in its technical guidance document published March 20: “Experience suggests that empirical use of convalescent plasma may be a potentially useful treatment for COVID-19.”
He recommended a detailed risk assessment of blood services to hospitals so that they can safely collect, process and store blood components in a way that ensures quality.
Doctors at SMLC and PGH say their patients have responded well to convalescent plasma, but it is too early to reach definitive conclusions about treatment.
“Some of them, their chest x-rays have improved, some inflammatory markers that we have verified have decreased in some of these patients … but we don’t want to pre-pump,” said Dr. Francisco López, head of Blood and Transplant Service at core at St Luke’s BGC. “We have to wait a week or two to really see the effect [of the plasma], but that’s what we’re seeing now. “
St Luke’s BGC administered its first plasma transfusion to a patient with COVID-19 on Saturday, April 11, while PGH announced that it received plasma from donors on April 10.
What happens during plasma collection, donation, and transfusion?
SURVIVOR. A patient recovered from COVID-19 donates plasma for convalescent plasma therapy. Photo courtesy of St Luke’s BGC Medical Center
For both hospitals, potential donors can call a hotline and be guided through the selection and donation process.
At PGH, a team will visit the donor to determine their eligibility. Once approved, the donor will be taken to the University of the Philippines-Manila (not PGH) for plasma or whole blood collection.
There are two ways to collect plasma: through an apheresis machine, which separates the blood into its various components, or by collecting complete blood. PGH collects plasma both ways, while SMLC collects only through apheresis.
When plasma is collected through an apheresis machine, it returns the red and white blood cells to the donor. This process produces 500 cubic centimeters or half a liter of plasma.
On the other hand, whole blood collection produces 250 ml or a quarter of a liter of plasma.
The plasma collection process can take anywhere from 40 minutes to an hour and a half. Donors through apheresis can donate again after 14 days, while whole blood donors can donate again through apheresis after 8 weeks.
Plasma is administered intravenously to the recipient who has a compatible blood type. This can take two to three hours.
In PGH, each patient receives one or two units of plasma, which are 250 milliliters (ml) each, while in SMLC, a patient receives one unit of 500 ml.
Since convalescent plasma is considered compassionate care and not an official cure for COVID-19, patients are asked to sign a consent form and a waiver prior to treatment.
Who can receive blood?
In SMLC and PGH, plasma is administered to COVID-19 patients who are seriously ill or progressing to severe illness.
López said a possible side effect of the plasma infusion would be an allergic reaction, although recipients receive Benadryl and Paracetamol to prevent that from happening. Receiving plasma can also be dangerous for patients with pre-existing heart conditions.
Deonne Gauiran, a hematologist at PGH, also said that most of the risks involved are related to transfusion, but that following standard blood donor screening, processing, and transfusion protocols helps mitigate them.
“There are other theoretical risks, such as antibody-mediated disease improvement (disease improvement in the presence of certain antibodies) and modulation of the immune response (so that patients who receive PC become more vulnerable to subsequent reinfection ) to be theoretical as of now and scientists are still studying these, “Gauiran said.
Still, exclusions are limited, Lopez said, and treatment can be done for almost anyone.
At St Luke’s, patients receiving plasma have also been receiving other compassionate care treatments and medications for the disease that are undergoing trials, Lopez said. Convalescent plasma is not the first line of treatment.
Who is eligible to donate blood?
Donors for convalescent plasma therapy meet the same requirements as blood donors, but hospitals have added additional criteria.
At SMLC, donors must have two COVID-19 negative swabs and an antibody titer test to make sure they already have antibodies in their blood.
After that, donors take tests for HIV, syphilis, hepatitis, malaria, and other diseases, which are routine tests done for blood donation.
PGH, on the other hand, says they choose their donors based on the following criteria:
- First priority: those who have been diagnosed by reverse transcription polymerase chain reaction (RT-PCR) in the past and have recovered from the disease without further symptoms for at least 14 days and with at least one negative RT result -PCR made during recovery.
- Second priority: those who have been diagnosed by RT-PCR in the past and have recovered from the disease without further symptoms for at least 28 days. These donors are eligible even without a negative RT-PCR result during recovery.
- Third Priority: Those who do not have the RT-PCR test to document their disease and have recovered from the disease without further symptoms for at least 28 days, but with a positive result for a test based on IgG anti-SARS-CoV antibodies -2 done in recovery.
Additionally, PGH donors:
- You must have a body weight of more than 50 kilograms.
- It can be of either sex (but additional tests should be done for those who have received blood transfusions or for women with previous pregnancies)
- You must have signed the informed consent for the donation.
Has it been used to treat other diseases?
Convalescent plasma therapy has been used as empirical therapy several times in the past.
Convalescent blood products were used as early as the 1880s to treat bacterial and viral infections in humans and in animal models. Studies were also conducted during the Spanish flu from 1918 to 1920 that suggested they could be an effective therapy.
More recently, studies have been conducted on its use to treat Middle East respiratory syndrome (MERS-CoV) and severe acute respiratory syndrome (SARS).
The WHO Detailed Guide on Blood Transfusion was published in 2014, when convalescent whole blood or plasma therapy was being used as an empirical treatment for Ebola.
Who is using it as a treatment for COVID-19?
In addition to the Philippines, other countries have been using convalescent plasma to treat COVID-19.
Small studios 10 or fewer patients have been conducted in China, and while the results appear promising, trials with hundreds of patients should be conducted to demonstrate the efficacy of plasma therapy. (READ: China Calls on Recovered Patients to Donate Plasma for Virus Treatment)
It is also being used in the USA. USA For clinical trials, patients who cannot participate in clinical trials and individual patient emergencies. The US Food and Drug Administration. USA He published recommendations for investigational convalescent plasma treatment COVID-19 on Monday, April 13. – Rappler.com
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