By Adam Townsend
The American Red Cross is seeking blood plasma donations from COVID-19 coronavirus survivors in the hope that their immune antibodies can help the sickest patients fight the infection.
This approach, called convalescent serum antibody therapy, has been effective against other viral infections -- it was one of the earliest treatments against viruses developed in the modern era.
But, as with so much else during the coronavirus pandemic, we have little solid data about whether this treatment is effective against the SARS-nCoV-2 virus that causes COVID-19.
"People who have fully recovered from COVID-19 have antibodies in their plasma that can attack the virus," the Red Cross website states. "Historically, convalescent plasma has been used as a potentially lifesaving treatment when new diseases or infections develop quickly, and no treatments or vaccines were available yet. The Red Cross has been asked by the FDA to help identify prospective donors and manage the distribution of these products to hospitals."
The site also provides a donor form to help the organization screen for potential donors. But those are difficult to find because of the continuing shortage of COVID-19 tests in the US; doctors must run three tests to confirm a donor is COVID-19-negative and could be a donor: two tests 24 hours apart that return negative results for viral DNA, plus a serology test that allows doctors to see how robust the immune response was.
Also, not every coronavirus survivor is a suitable donor. The amount of coronavirus-specific antibodies in your blood has to be high enough to be effective in a patient.
Charles Patrick Davis, MD, PhD is a retired emergency room doctor, professor of emergency medicine and a microbiologist. He is also a MedicineNet author and member of the site's editorial board. He gives a basic rundown of what serum antibody therapy is and how it works, as well as some of the drawbacks to this therapy.
MedicineNet: What are convalescent serum antibody treatments for COVID-19?
Dr. Davis: A medical professional collects blood plasma from a COVID-19-recovered donor with IgG (immunoglobulin G) antibodies specific to the SARS-CoV-2 virus that causes the deadly respiratory disease.
This serum is then given to people who are having a harder time fighting off the virus. That way, they now have antibodies specific to COVID-19.
These donor antibodies may potentially help the patient fight off the disease more effectively.
Are they using serum treatments for COVID-19 patients right now?
There is a precedent for this; what people are doing is pretty straightforward.
Serum treatments have also been used in the past. Most recently and publicly, it was used to treat Ebola patients in 2016.
There is no solid evidence yet that serum treatments are effective against COVID-19, but the FDA has approved convalescent serum use in the treatment of severe COVID-19 cases under compassionate use.
At least two major studies on this methodology are underway as of early April, 2020.
Can I donate plasma for convalescent serum treatments of COVID-19 patients?
Serum donor programs aren't set up in most of the country, but you can fill out a Red Cross donor form if you've recovered from a confirmed infection and someone will contact you eventually, according to their website.
Serum donation on any scale relies on accurate testing, and COVID-19 test kits were still in short supply as of early April. In theory, the process to donate convalescent serum goes as follows:
- A person who has recovered from the SARS-CoV-2 virus that causes COVID-19 must be tested to make sure:
- The virus is completely gone from their system
- Their immune response was hearty enough to make the serum effective
- Plasma is collected only from those who have recovered from COVID-19 and have produced high levels of IgG antibodies (immmunoglobulin G-type, which makes up the bulk of the immune response).
- The convalescent COVID-19 patient donates blood.
- A lab -- ideally one belonging to a blood bank working in tandem with a hospital on a COVID-19 serum program -- will test the blood for other infections like HIV or hepatitis before separating the plasma for use on terminal COVID-19 patients.
They can have convalescent patients donate plasma fairly quickly after they recover. And it is possible to get permission to make serum preparations locally, done in conjunction with a blood bank who can separate out the serum.
If I've recovered from COVID-19, where can I donate blood to help others?
Centers are difficult to locate because you're looking at a compassionate use designation. As a result, this therapy is restricted to patients in the worst shape.
But, if the early anecdotal reports are promising, this could take off as a treatment modality.
If it's found to be effective, it would be reasonable to try a prophylactic (preventative) use in people with compromised immune systems, other health conditions, or who work in hospitals and health clinics.
It sounds as if this is a therapy that could easily be scaled up with existing technology, provided it's proven effective.
My opinion is that logistically, you have the possibility of even doing it in a local hospital.
It's not difficult to separate the cells from the serum. It would be useful to go through a blood bank because they are set up to do all the testing for hepatitis, HIV, etc. That way you can be relatively sure the serum isn't causing any problems.
With single-donor serum, if you have AB serum, you want to give it to someone with an AB blood type, A for an A blood type, etc. Theoretically, you could give blood plasma from anyone to anyone else, regardless of blood type, but blood-type matching cuts down on risk.
That's the general approach, anyway.
The other way to do it is quite extensive. In the long run, you could collect serum from multiple patients with strong immune responses, isolate the IgG antibodies, and pool them together in a serum that could be given to anyone.
But that would require more research to see if the treatment is even effective for COVID-19.
Eventually, you could hypothetically produce monoclonal antibodies that could be synthesized on an industrial scale and made available as a treatment or prophylaxis (preventative medicine).
What are the drawbacks of convalescent serum antibody therapy?
The antibodies don't last forever. If you lose the antibodies from your serum treatment, you are potentially susceptible again. Also, your immune response might not be as effective against SARS-CoV-2 as it would have been without that serum treatment.
That's why it would be better to do a long-term study on this. There are plenty of reasons why this therapy isn't first-line treatment for viral infection. Its effectiveness is spotty and varies from patient to patient, and among different types of viral infections.
- The serum has to be sterile,
- It has to be proven to have at least a high concentration of immunoglobulin so that it can be effective,
- The effectiveness of the serum depends on the level of each donor's antibodies.
There is a possibility of allergic reaction to the serum that has to be carefully monitored. Right now, they're giving it to people who don't have much of a chance, and if someone has an allergic reaction in that condition, it will be catastrophic.
That's why it's only approved as compassionate use; it's only for people who appear terminal for whom other treatment options have failed.
Furthermore, you're not going to be able to do this treatment without first-line testing to identify people as donors. We need more COVID-19 tests done, and they need to be done much more rapidly.
If you are fully recovered from a verified COVID-19 diagnosis, and you want to sign up for the Red Cross's convalescent plasma donation program for COVID-19, the application form is on the organization's website: https://www.redcrossblood.org/donate-blood/dlp/plasma-donations-from-recovered-covid-19-patients.html
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