Many of us are wondering when an available drug or vaccine is coming out, but it’s totally not coming tomorrow, or the next week, or next month (a widely available public vaccine that is, as the earliest one’s are still on trials). But what do we have in abundance right now? Purified blood plasma.
Blood product transfusions have been done before to combat diseases based on our medical literatures. Survivors who donated blood may have contributed to a 50% reduction of death in 1918 in the midst of the Spanish flu pandemic. A measles outbreak in Pennsylvania (1934) was halted when serum harvested from an infected student was used to treat 62 fellow students – afterwards only three of the students developed measles and all of them are mild cases.
Doctors have been trying many possible cures for COVID-19, the latest being convalescent plasma therapy, a treatment that uses the antibodies of CoviD-19 survivors to boost the immune systems of the critically ill. It’s one of many treatments that are given as compassionate care, that is, the use of drugs and cures that are still in the testing stages, in hopes of easing the symptoms of those who are sick.
What is Convalescent Plasma Therapy?
When a person has Covid-19, their immune system responds by creating antibodies, which attack the virus. Over time these build up and can be found in plasma, the liquid portion of the blood. Plasma is the part of the blood that remains when red blood cells, white blood cells, platelets, and other cellular components are removed. It contains water, salts, enzymes, antibodies, and other proteins. Convalescent plasma therapy is a kind of passive immunization that involves giving the plasma of a recovered patient to infected patients to boost their immune system and help their bodies fight the disease.
What is the difference between Passive Immunity and Active immunity?
Active immunity happens when a body is exposed to an antigen, a molecule or molecular structure commonly present in pathogens (ie. Microbes, viruses etc.) and triggers the body to create antibodies against it. Passive immunity on the other hand happens when the body is given antibodies, rather than leaving its own immune system to produce them. Immunoglobulin therapy and antiserum therapy are examples of (artificial) passive immunity, but passive immunity also happens naturally – when a mother’s antibodies are transferred to the fetus through the placenta in pregnancy.
Active immunization lasts longer, and sometimes for life. Naturally a person can get infected for example, with varicella zoster (chicken pox) when he / she has not yet been exposed before. After the person’s body is cured, it has the ability to produce antibodies for chicken pox and thus can be considered immune. Artificially, this can happen with vaccination, vaccines are generally pathogen particles killed or weakened, which then stimulate the body to produce antibodies without suffering the consequences of infection.
(The author of this article is vaccinated with varicella vaccine. While not having experienced chicken pox before, he will most likely not experience chicken pox for life due to it, Just a reminder that vaccines help!)
Vaccines work by teaching the body to make its own antibodies to an infectious agent without a person ever becoming infected. This is why they are among the most powerful weapons in public health. But the creation of the novel coronavirus vaccine might be harder than companies expect, because this new threat is just not well understood enough, not yet at least. You need to have some fundamental understanding of the immunology and the virus before you can develop a vaccine and we still don’t have that. Many companies, including the biotechnology firm Moderna and the large pharmaceutical companies Johnson & Johnson and Sanofi, are working hard to develop vaccines quickly.
With this in mind the first line of defense we could provide for Covid-19 is through Convalescent plasma, and then IVIG, two passive immunization treatments, especially those who are older and at much higher risk for complications. We then wait for further advances of our researches – a monoclonal antibody drug could reach a greater number of patients. We also need antiviral drugs, such as remdesivir, being tested by Gilead Sciences. And a vaccine could do the most to slow or stop transmission.
Global studies about plasma therapy
More recently, plasma-derived therapy was used to treat patients during outbreaks of Ebola and Bird flu. And on Wednesday the Japanese drugmaker Takeda Pharmaceutical Co. said it was developing a new coronavirus drug derived from the blood plasma of people who have recovered from Covid-19. Its approach is based on the idea that antibodies developed by recovered patients might strengthen the immune system of new patients.
In February, doctors in Shanghai set up a special clinical to administer convalescent plasma to select patients who were newly infected with coronavirus. “In China, we’ve only heard anecdotal reports of encouraging results. Nothing has been published yet,” said Greg Poland, a physician and infectious disease expert at the Mayo Clinic in Rochester, Minn. “But this approach is definitely worth trying.”
Plasma Collection and Donation
There are two ways to collect plasma: through an apheresis machine, which separates blood into its various components or through whole blood collection. When plasma is collected through an apheresis machine, it returns the red and white blood cells to the donor. This process yields 500 cubic centimeters or half a liter of plasma. On the other hand, whole blood collection yields 250 mL or one-fourth liter of plasma. The process of collecting plasma 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 via apheresis after 8 weeks.
The plasma is given intravenously to the recipient who has a matching blood type. This can take two to three hours. 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 before the treatment.
Plasma is administered to COVID-19 patients who are critically ill or progressing to severe illness. A potential side effect of plasma infusion would be an allergic reaction, though recipients are given Benadryl and Paracetamol to prevent that from happening. Receiving plasma may have complications when a person has pre-existing heart conditions.
Some of our hospitals in the nation have sent out contacts to those who may want to donate:
There is Hope
Plasma therapy would offer many advantages. A CoviD-19 vaccine are many months away. Plasma is available now. The price of antiviral medications (when available) may create access issues for patients in resource-limited countries. Plasma is relatively cheap. Coronavirus tests, masks, face shields and ventilators are all scarce resources. Plasma is abundant and will only increase as more patients recover. Convalescent plasma may serve as another stop-gap measure against the pandemic before we get to an effective vaccine. Science will always be there as a tool, but it will always be up to us as individuals on how we use this tool to help others. Stay informed, stay safe.