Effect of Convalescent Plasma Therapy on COVID-19 Patients: A Retrospective Study

Background: Coronavirus disease 2019 (COVID-19) was first detected in December 2019 in Wuhan, China. Different treatments have been used to fight against the virus; however, one of the most effective and accessible is convalescent plasma therapy (CPT). Objectives: The present study investigated the effect of CPT on improving the clinical conditions of COVID-19 patients. Methods: This study was conducted on 440 individuals, including 220 COVID-19-recovered individuals as plasma donors and 220 plasma recipients, in Shiraz, Fars province, Iran, from May 2020 to February 2021 using random sampling. After complete recovery from COVID-19, patients were recalled for apheresis and plasma isolation for convalescent plasma (CP) preparation; they were referred to the blood donation centers of Shiraz. According to the hospital request, compatible and related plasma was sent for COVID-19-hospitalized patients. At the same time, hospitals were asked to send the clinical condition documents of the patients based on the medical records and the outcomes after CPT. The Iranian Blood Transfusion Organization evaluated the results. Results: The median antibody titer was 1300. Titers higher and lower than 1300 were considered high and low, respectively. Blood group O had 54 times higher antibody titers above 1300 than other blood groups (odds ratio (OR) = 54, confidence interval (CI): 19.5 - 205.3, P < 0.001). Additionally, most deceased cases received plasma with antibody titers less than 1300 (OR = 0.08, CI: 0.009 - 0.36, P < 0.001). Nevertheless, most discharged patients received plasma with antibody titers higher than 1300 (OR = 1.5, CI: 1.06 - 2.3, P = 0.01). Moreover, when donors’ antibody titer was higher than 1300, the chance of survival increased by 50%. In addition, the results of this study showed higher mortality in patients whose volume of received plasma was less than 387 mL (OR = 0.3, CI: 0.10 - 0.91, P = 0.018). However, patients who received more than 387 mL CP were more likely to discharge (OR = 5.7, CI: 3.7 - 8.8, P < 0.001). Conclusions: Using blood group O plasma with a minimum volume of 387 mL can be very effective in improving the clinical symptoms of patients with COVID-19 and increasing the chances of survival for these patients.