The New York Blood Center (NYBC) is the first blood-gathering organization in the U.S. to collect plasma from COVID-19 patients to use as a possible treatment for the disease.
Before antibiotics rendered the practice moot, it was common to treat infectious bacterial diseases by infusing the blood of recovered patients into those struggling with infection. That approach has also been tried against viral infections like H1N1 influenza, SARS and MERS, with inconsistent success. Some patients benefited, but other did not and doctors don’t have a clear understanding of why. But during an evolving pandemic like COVID-19, plasma-based treatments can provide a critical stop-gap while therapies and vaccines are developed.
The idea is relatively simple, and based on the concept of passive immunity. People who have recovered from an COVID-19 infection have likely done so because their immune systems developed strong immune responses to SARS-CoV-2, the virus that causes the illness. As a key part of their response, they make antibodies, including both general microbial killers and specialized cells that target just the proteins found on SARS-CoV-2. In theory, these antibodies could be taken from a recovered COVID-19 patient, and infused into someone recently infected with the virus. “The thought is that if you passively infuse someone who is actively sick, the antibodies may temporarily help a sick person fight infection more effectively, and get well a little bit quicker,” says Dr. Bruce Sachais, chief medical officer of New York Blood Center Enterprises.
While the therapy is still experimental, the U.S. Food and Drug Administration on March 24 allowed doctors to use plasma from recovered patients to treat those with “serious or immediately life-threatening COVID-19 infections” under an emergency approval system. Doctors can apply to the FDA to use it for their patients, and the agency will review the requests quickly and make decisions on a case by case basis.
Sachais says NYBC is ready to begin collecting blood from recovered patients who have tested negative for active viral infection, and met other requirements to ensure their plasma is safe to infuse. The first donors will likely come from hospitals who have successfully treated patients, and the donated plasma will go back to those hospitals to treat their sickest patients. This week, Mount Sinai Health System announced that it would begin working with NYBC to start treating some of its more severely ill patients with the therapy. But Sachais says he is working with other blood centers and hospitals to create a system where donated plasma can be stored and shared among them.
For now, each patient will likely receive one unit of plasma, which is about 200-250 cubic centimeters. But because the amount of antibody in donors may vary, researchers are currently seeking ways to produce a more concentrated and consistent dose. Emergent BioSolutions, a biopharmaceutical company in Maryland, is working on a way to pool plasma from recovered patients and use that to create concentrated doses of antibodies, for example. That way, scientists don’t have to select out donors with the highest amount of antibodies, and can accept plasma from a wide pool of recovered patients, according to Laura Saward, head of Emergent’s therapeutic business unit.
The company is also looking to other sources for the antibodies—specifically, horses. It already relies on horses to produce treatments for botulism, and its researchers are adapting that platform to produce antibody-rich plasma against COVID-19. The horses are exposed to fragments of SARS-CoV-2 and generate antibodies to the virus, and because of the animals’ sizes, the volume of plasma they produce could help to treat more than one patient at a time. “We could quickly get to the point where we have multiple horses donating plasma on a weekly basis to help continuously produce those antibody doses,” says Saward. “The thought is that a smaller dose of equine plasma would be effective in people because there would be higher levels of antibody in smaller doses.”
Because Emergent’s technology involves additional steps than processing plasma from one person and infusing it into another, Saward says testing of the company’s human and equine plasma will take a few months. The company plans to begin testing its products in people toward the end of the summer.
Sachais is also considering ways to concentrate the antibody in smaller doses of plasma. But in the meantime, as more people receive units of donated plasma through blood centers like NYBC, doctors will learn more about how much protection the plasma provides, and determine if it could be helpful in preventing infection in high risk people like health care workers. “We are working with national organizations as well to share our experience with them,” he says, “and potentially share inventory of plasma as time goes on, depending on how the pandemic plays out, to make sure the product is collected and distributed where it’s needed.”
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Contributor: Alice Park