Collection of COVID-19 convalescent plasma in institute for transfusion medicine of republic of North Macedonia and evaluation of anti-SARS-CoV-2 antibody concentration in different donors subgroups

ABSTRACT

Background: Plasma collected from patients that have recovered from an infectious disease has been transfused over many decades for prophylaxis and treatment of various infectious diseases. Taking into consideration the expansion of COVID-19 pandemics, we started the COVID-19 convalescent plasma (CCP) programme. Aims: The aim of our study is to show our experience with collecting the CCP and to evaluate the SARS-CoV-2 antibody concentration in different convalescent plasma donors' subgroups. Methods: This is a prospective study performed in the Institute for Transfusion Medicine of Republic of North Macedonia since 30 April 2020 till July 2021. Antibody testing was performed at the Institute for Immunobiology and Human Genetics in Skopje using CLIA method with Snibe Maglumi SARS-CoV-2 S-RBD IgG (quantitative) with IgG cut-off larger than 5 AU/ml. All potential donor were tested for negative RTPCR for SARSCoV-2 before donation, anti-SARS-CoV-2 antibodies, anti- HLA antibodies (where applicable), blood count, blood group, TTI and biochemistry. Preferred method for plasma collection was plasmapheresis which was performed with Terumo BCT Trima Accel and donation of whole blood, depending on the donor preference and venous access. All donors signed inform consent for donation and inclusion in the study. Results: There were 1476 potential CCP donors, but only 700(47.9%) donors fulfilled all the criteria and we obtained 793 units of CCP;639 (80.6%) units from whole blood donors and 154 (19.4%) CCP units from 61 plasmapheresis donors, 485 (69.3%) males and 215 (30.7%) females. Mean age of the donors was 40 years (range 18-63). Mean value of SARS-CoV-2 S-RBD IgG concentration was 31.05 AU/ml, (range from 5.1 AU/ml to >100 AU/ml), mean value of SARS-CoV-2 S-RBD IgG in men was 37.6 AU/ml and 28.9 AU/ml in women (p < 0.05). Distribution of CCP donors according to the ABO blood group was 301 blood group A (43%) with median value of SARS-CoV-2 S-RBD IgG = 27.15 AU/ml, 220 blood group O (31.4%) median value of SARS-CoV-2 S-RBD IgG = 32.1 AU/ml, 116 blood group B (16.6%) median value of SARS-CoV-2 S-RBD IgG = 35.9 AU/ml and 63 donors had blood group AB (9%) median value of SARS-CoV-2 S-RBD IgG = 26.45 AU/ml. There were 69 donors that were previously hospitalized with mean value of SARS-CoV-2 S-RBD IgG = 48.6 AU/ml, and 629 that were treated at home with mean value of SARS-CoV-2 SRBD IgG = 29.1 AU/ml (p < 0.05), of which 578 had symptoms with mean value of SARSCoV- 2 S-RBD IgG = 29.1 AU/ml and 51 were asymptomatic with mean value of SARS-CoV-2 S-RBD IgG = 29.3 AU/ml. The CCP donors had the following distribution according to the age 125 donors in the 18-29 age group with median value of SARS-CoV-2 S-RBD IgG = 23.0 AU/ml, 200 donors in the 30-39 age group with mean value of SARSCoV-2 S-RBD IgG = 28.2 AU/ml, 217 donors in the 40-49 age group with mean value of SARS-CoV-2 SRBD IgG = 32.9 AU/ml and 156 donors in the 50-63 age group mean value of SARS-CoV-2 S-RBD IgG = 38.3 AU/ml (p < 0.05). Summary/Conclusions: The collection procedures are safe and effective and collected CCP units were with high concentration and quality. The concentration of SARS-CoV-2 S-RBD IgG in CCP obtained from previously hospitalized patients was significantly larger than in ones that were treated at home. The concentration of SARS-CoV-2 S-RBD IgG was higher in men, in advanced age group and in donors with blood group B. The further studies are needed to clarify the impact of different variables on antibodies concentration/ titre in donors.