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Colton Underwood, 28, of Denver talks with Dr. Kyle Annen, medical director of Transfusion Services and Patient Blood Management while giving convalescent plasma on May 14 at the Blood Donor Center at ChildrenÕs Hospital Colorado on the Anschutz Medical Campus.
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Colorado doctors and researchers are studying whether fluids donated by people who recovered from the new coronavirus could give others a better chance of surviving, although one doctor warns that it isn’t a long-term solution.

The experimental treatment involves giving plasma — the liquid part of blood — from COVID-19 survivors to people who are seriously ill from the new coronavirus. The idea is that the antibodies in the survivors’ plasma will give a boost to sick patients’ immune systems. Different antibodies react to a specific type of virus, bacterium or toxin, and some can neutralize their target, while some signal other immune cells to eat the invader.

Normally, new treatments have to go through a rigorous process to prove they work and don’t cause harm. The U.S. Food and Drug Administration is allowing expanded use of donated plasma for people who are severely sick with COVID-19, though.

Research is ongoing, but so far there appears to be a benefit from using what’s known as convalescent plasma, at least in some situations, said Dr. Kyle Annen, medical director of the transfusion service at Children’s Hospital Colorado. Children’s is one of the blood banks in the Denver area collecting and distributing convalescent plasma.

“It seems the evidence is slowly building that this is a benefit in COVID,” she said.

This type of treatment showed some success during the 1918 influenza epidemic and the outbreak of SARS, another coronavirus that killed more than 700 people in 2003, said Dr. Michael Joyner, a Mayo Clinic consultant who is leading the research into convalescent plasma. Mayo Clinic is the umbrella group that worked with the FDA to arrange permission for hospitals to give plasma to patients under certain circumstances, he said.

The FDA is allowing patients who are seriously ill, or whose doctors determine their conditions are deteriorating enough that they will become seriously ill, to receive one or two units of donated convalescent plasma. Patients also have to be at least 18 and able to understand that the treatment is experimental, said Dr. David Beckham, an associate professor in the infectious diseases division on the University of Colorado’s Anschutz Medical Campus. People who have had previous bad reactions to plasma therapies or who have a condition that make receiving more fluid dangerous, like a severe heart or kidney problem, might not qualify.

Other types of plasma therapy can produce side effects ranging from a slight fever to plummeting blood pressure, though severe bad reactions are rare, Beckham said. Still, it’s important to make sure this type of plasma is as safe as any other type, and to establish if there are other risks, such as interfering with the body’s own immune response, he said.

So far, 16 Denver-area hospitals have enrolled about 50 people in a study to determine if the treatment is safe and get some sense if it’s effective, Beckham said. They need about 200 patients before they start comparing those who got the treatment to similar people who didn’t, he said. If the early data looks good, they’ll study more patients to determine who benefits, and how best to give the plasma.

“We’re still trying to understand what will help these patients and what won’t,” he said.

Dr. Alan Miller, assistant chief medical director of research and chief medical director of oncology at SCL Health, said SCL’s hospitals in Colorado and Kansas have treated more than 50 people with convalescent plasma. Nationwide, about 7,500 patients have received the therapy, and early data suggests it works better before patients need a ventilator or are experiencing organ failure, he said.

Johns Hopkins University is leading a separate trial to figure out if there’s any advantage in giving plasma with antibodies to people who were exposed to the virus but aren’t sick enough to be hospitalized, Miller said. It’s possible that future studies will determine plasma works better in combination with certain drugs, or that the antibodies should be concentrated and not given with full plasma, he said.

“Right now we’re starting the very basic ways of doing it,” he said.

Donors needed, especially with AB blood

Different blood centers have slightly different rules for who can donate. Some want to see a positive swab test proving the donor had COVID-19, while others will accept an antibody test, given after the donor recovered. Donors must wait until they’re symptom-free for at least 14 days before giving plasma, Annen said.

When a person donates plasma, a machine removes the red and white blood cells and returns them to the donor. The liquid portion, which contains antibodies, then goes to patients. Donors also have to meet all normal blood donation criteria, such as weighing at least 110 pounds and being in general good health.

People who have blood type AB are especially in demand, because their plasma doesn’t contain antibodies that could attack the blood cells of a person with a different type, Annen said. They also are trying to prioritize donors who have never been pregnant, because a mother’s body will sometimes develop antibodies to parts of the father’s immune system, and those could attack an unlucky plasma recipient whose immune system was similar to the father’s, she said.

After a person has donated, staff verify that their plasma contains the level of antibodies recommended by the FDA, Annen said. Studies are ongoing to determine if that’s the right threshold, she said.

At first, collections were slow, but now they’ve collected enough to meet local demand and send some to hospitals in Chicago and Utah that haven’t been able to collect enough, Annen said.

Dr. Rebecca Boxer, medical director of clinical trials at Kaiser Permanente Colorado’s Institute for Health Research, said Kaiser is reaching out to people who recovered from COVID-19 and are in generally good health to see if they’re interested in donating plasma.

Healthy people can donate plasma as often as once a week, Boxer said. As many as 10% of people who have had COVID-19 may not develop antibodies, so if someone’s plasma shows no antibodies, they wouldn’t be asked to donate again, she said.

Building a longer-term strategy

Others are collecting plasma to try to develop a second-generation treatment. Vlasta Hakes, director of corporate affairs for Grifols, a Spanish company that owns Biomat USA plasma donation centers in Colorado, said the plasma they collect won’t go for immediate patient care. The plan is to extract the antibodies from many donors’ plasma and use them to make a treatment that can be standardized and tested. The treatments people receive after possible exposure to tetanus or rabies are based the same idea, she said.

“Right now our goal is to collect enough plasma to make the medicine for a clinical trial,” she said.

There is precedent for developing treatments from donated plasma, Dr. Nahid Bhadelia, medical director of the Special Pathogens Unit at Boston University’s School of Medicine, said on a call with reporters. For example, drugmakers were able to clone antibodies taken from Ebola survivors, meaning they could give those antibodies to infected people without needing a constant supply of donors, she said.

Miller cautioned against seeing plasma, or any of the drugs being studied for COVID-19, as the solution to the pandemic. With no treatment proved to be effective, it’s important to keep practicing social distancing and to wear a mask to limit the virus’ spread, he said.

Despite all the work being done on plasma therapy, Beckham said he doesn’t expect it to be a long-term solution. Right now, it’s something that might help patients while other labs work on more targeted approaches like a vaccine or antiviral drug, he said.

“I see it as a bridge,” he said.

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