In recent months, there has much been discussion about potential treatments to cure and alleviate the symptoms caused by COVID-19. One such treatment that has received attention from researchers and public health officials is convalescent plasma therapy (CPT), which was granted emergency use authorization (EUA) by the US FDA in late August, 2020 (3). The FDA’s decision to grant an EUA for plasma therapy has caused much speculation since the studies done on plasma therapy for COVID-19 treatment are limited to non-randomized observational studies rather than randomized control trials. We have reviewed the available research to help clarify what is currently known about plasma therapy as a potential treatment for COVID-19.
What is CPT
Convalescent plasma therapy (CPT) involves taking blood donated by recovered individuals and transfusing it to COVID-19 patients to help boost their immune system’s ability to fight off the illness. The donated blood is first processed to remove red blood cells leaving the plasma and antibodies behind, which are then transfused to patients (1). In the past, plasma therapy has been used to prevent infection in exposed people and to treat infected people during outbreaks of other diseases such as polio, the Spanish flu, and rabies. There have even been case reports from the MERS and SARS coronavirus outbreaks that show the benefits of CPT including faster clearance of the virus (2). Evidence for the therapeutic efficacy of plasma therapy in other diseases has led researchers to investigate it as a treatment for COVID-19 patients.
Current Research on CPT
Current research on the efficacy of plasma therapy is limited yet promising. The results from a Chinese study in which 10 patients were given 1 dose of donated plasma showed improvement of clinical symptoms within 3 days and clearance of the virus in 7 days (4). Additionally, the patients did not show any severe adverse effects suggesting that the plasma therapy was well tolerated. The outcome of this study indicates that while more better controlled research trials need to be conducted on the optimal dosage and timing, plasma therapy does show potential for therapeutic effects.
More recently, preliminary results from an FDA sponsored study in which 35,000 COVID-19 patients received plasma therapy were released before publication. The results show reduced mortality when COVID-19 patients were given plasma earlier and when they were given plasma with higher antibody levels (5). Since there was no control group in this study, it has received criticism for being the basis of the EUA (6).
Limitations in Research
While current research is showing great potential for plasma therapy in COVID-19 patients, the design of these studies along with the presence of many confounding factors has caused much skepticism. Most of the studies done on COVID-19 plasma therapy have been non-randomized observational studies. In order to understand the true efficacy of plasma therapy in treating COVID-19, randomized controlled studies in which the results are compared to a group of control patients who receive the standard treatment need to be conducted. Without being able to compare the results to a control group, there is no way to actually measure whether the plasma therapy is working.
Additionally, researchers have questioned whether the survival rates improved for other reasons in the FDA sponsored study. The patients treated in that study were likely treated more recently (6). Since protocols for COVID-19 treatment have improved compared to the beginning of the pandemic, the mere timing of these patient’s care could be the reason for their improvement rather than the plasma therapy. Furthermore, most of the patients in the FDA sponsored study were also receiving at least one other form of therapy for COVID-19 such as antivirals, antibiotics, antifungals, and/or steroids (2). This makes it difficult to distinguish if clinical improvements were due to the plasma therapy, the alternate therapies, or a combined effect of both.
What we Do Know About CPT
While results of most studies on plasma therapy are limited, they are still promising and call for investing in more structured and controlled studies to further understand the therapeutic benefits of plasma therapy for COVID-19 patients. The FDA’s emergency use authorization for plasma therapy in COVID-19 treatment is far from formal approval, which would require more comprehensive controlled studies (2). What we do know is that plasma therapy as COVID-19 treatment appears to be safe and the preliminary research has shown enough signs of effectiveness for it to be considered as a treatment option.
- Convalescent Plasma Therapy
- COVID-19 and Convalescent Plasma
- FDA Issues Emergency Use Authorization for Convalescent Plasma
- Effectiveness of convalescent plasma therapy in severe COVID-19 patients
- Effect of Convalescent Plasma on Mortality among Hospitalized Patients with COVID-19