Efficiency and safety of convalescent plasma therapy in patients with COVID-19: a systematic review

Abstract

INTRODUCTION. High mortality during the pandemic of COVID-19 conducted the research for all available treatments. Convalescent plasma (CP) has become valuable empirical resource for health support, especially during the initial phase of COVID-19 pandemic. It still draws attention of many scientists, while data on the effectiveness of CP is rather controversial. OBJECTIVES. The purpose of this review is to analyze the results of modern studies on the efficacy and safety of the clinical use of CP. MATERIALS AND METHODS. The search for publications was carried out in electronic databases PubMed, MedRxiv, Cochrane Library, Cochrane COVID-19 study registry from June 7, 2021 to December 20, 2021. RESULTS. The article analyzes data from recent retrospective and prospective studies related to CP therapy. The use of CP is known since the 1880s in the treatment of diphtheria, Spanish flu, measles, polio. In the 21st century CP has been used in the epidemic of Ebola, H1N1pdm09, other SARS1 and MERS coronaviruses. CP therapy is based on the concept of passive immunization and includes the infusion of antibodies from convalescent donors with virus-neutralizing activity (VNA). Pathogen reduction technologies are used to minimize the risks of transfusion-transmitted infections. Historical and current data confirm the safety of CP use. The criteria for effectiveness and timing for transfusion of the CP were considered. Clinical data is presented confirming the effectiveness of CP in certain groups of patients. CONCLUSIONS. The use of CP is safe and reasonable in seronegative patients with COVID-19 on the early stages of the disease or in the presence of an immunodeficiency. CP with high VNA titers has the highest efficiency. CP therapy in severe patients on the late stages of the disease does not provide disease regression and increased survival.