Background: Covid-19 spread through blood transfusion has not yet been reported. Despite the prevailing pandemic, there are no recommendations available as yet for testing SARS-CoV-2 antibodies as part of blood screening. Objective: To determine the seroprevalence of SAR-CoV-2 antibodies, its clinical significance and to identify if total antibodies(IgA, IgM, IgG) should be tested or just the specific IgG antibodies only. Method: Consecutive blood donors donated were screened for standard serological panel of HbsAg, Anti-HCV, Anti-HIV and Syphilis using Cobas-411 analyser and Malaria. All seronegative donors were then screened for COVID serology using the same instrument. These results were compared with the blood donors' seroprevalence checked in a cohort in the first week of June 2020. Pre-COVID-19 period (October 2019) blood donors' archived samples were also compared. Donors who were positive on ECLIA were then tested for specific antibodies (IgM or IgG) by ELISA. Results: A total of 380 healthy blood donors were included. All were males with the mean age being 30.6 ± 6.3 years. Ten pre-pandemic samples did not show COVID-19 antibodies, whereas out of 70 samples in the 3rd week of June, only 15 (21.4 %) were positive. However, in July out of the 300 blood donors, 113 (37.7 %) were found to be reactive. To reconfirm our findings, these 113 donors were then tested on ELISA for presence of IgG specifically. Out of these 128 samples, 81 were IgG positive, 23 were borderline positive and 24 were negative. Conclusion: Almost 40 % of blood donors are now seroconverted for COVID-19. This is a reflection of widespread seroprevalence in the adult male population.

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Background: Daratumumab is a human monoclonal antibody used for the treatment of multiple myeloma, which binds to CD38, a protein that is expressed on red blood cells (RBCs). Therefore, the plasma of these patients reacts with the RBCs producing a panreactivity and interfering in the transfusion compatibility testing. Panagglutination may persist for up to 6 months after the last infusion of daratumumab. An anti-CD38 antibody for treatment of multiple myeloma shows a strong interference in the indirect antiglobulin test (IAT) where most of the reactions turn to unspecifically (wrong) positive. The time consuming standard technique using Dithiothreitol (DTT) counteracts the interference but has major drawbacks like destruction of Kel antigens or hemolysis. The DaraEx ® compound inhibits the agglutination effect of anti-CD38 in IAT without side effects. DaraEx ® is a neutralizing agent for the inhibition of the agglutination effect of the anti-CD38 antibody daratumumab in IAT. Aims: To validate the procedure to resolve the interference of daratumumab in transfusion compatibility testing using red cells treated with DaraEx ® for the inhibition of the agglutination effect of the anti-CD38 antibody daratumumab in IAT. Daratumumab can interfere with crossmatching and antibody screening in the IAT, which will allow us to identify a clinically significant antibody that has been initially masked by the presence of daratumumab. Methods: The study has been conducted in 25 plasma samples of patients diagnosed with multiple myeloma who have been treated with daratumumab. Irregular antibody screening tests and CrossMatching were performed on all of them, being positive in all cases. We performed the technique to eliminate reactivity by treating the red cells used in compatibility tests with DaraEx ® , which neutralizes CD38 on the surface of the erythrocyte, thereby preventing Daratumumab from binding and inducing agglutination. The material used was DaraEx ® , 0.9% NaCl LISS/Coombs ID-Cards and Test cell reagents for the ID-System; We performed the method in Biovue Column Agglutination Technology and gel card systems. Results: After performing the technique, we were able to eliminate panreactivity in both Irregular antibody screening tests and CrossMatching. Summary/Conclusion: Daratumumab causes panreactivity in vitro by binding to CD38 on reagent RBCs. It is necessary to do a baseline antibody screen (type and screen) before starting the treatment with daratumumab. Treating reagent RBCs with DaraEx ® is a useful easy and quick method to mitigate the interference created by antiCD38 mAbs in pretransfusion testing. DaraEx is a quick and simple procedure; it doesn't affect other antigens or alloantibody reactions. It doesn't have side effects like destruction of blood group antigens or hemolysis as described for the standard DTT treatment. Therefore, we consider it a very useful technique to resolve interferences produced by daratumumb with blood compatibility testing. We believe that it is essential to have a validated techni...