Yonsei Med J.  2021 Sep;62(9):799-805. 10.3349/ymj.2021.62.9.799.

Effectiveness of Convalescent Plasma Therapy in Severe or Critically Ill COVID-19 Patients: A Retrospective Cohort Study

  • 1Departments of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
  • 2AIDS Research Institute, Yonsei University College of Medicine, Seoul, Korea
  • 3Department of Internal Medicine, Seoul Medical Center, Seoul, Korea
  • 4Departments of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea


Coronavirus disease-2019 (COVID-19) is a novel respiratory infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); there are few specific treatments. Convalescent plasma (CP), donated by people who have recovered from COVID-19, is an investigational therapy for severe or critically ill patients with COVID-19.
Materials and Methods
This retrospective cohort study evaluated the effectiveness of CP therapy in patients with severe or lifethreatening cases of COVID-19 at two hospitals in Seoul, Korea, between May and September 2020. Clinical outcomes were evaluated in 20 patients with CP therapy in a descriptive manner. Additionally, the changes in cycle threshold (Ct) values of 10 patients with CP therapy were compared to those of 10 controls who had the same (±0.8) initial Ct values but did not receive CP.
Of the 20 patients (mean age 66.6 years), 18 received high-dose oxygen therapy using mechanical ventilators or high-flow nasal cannulas. Systemic steroids were administered to 19 patients who received CP. The neutralizing antibody titers of the administered CP were between 1:80 and 1:10240. There were two ABO-mismatched transfusions. The World Health Organization ordinal scale score and National Institutes of Health severity score improved in half of the patients within 14 days. Those who received CP showed a higher increase in Ct values at 24 h and 72 h after CP therapy compared to controls with similar initial Ct values (p=0.002). No transfusion-related side effects were observed.
CP therapy may be a potential therapeutic option in severe or critically ill patients with COVID-19.


Convalescent plasma treatment; COVID-19; neutralizing antibody; cycle threshold (Ct) value
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