key: cord-349669-o3eelqcw authors: Stadlbauer, Daniel; Baine, Ian; Amanat, Fatima; Jiang, Kaijun; Lally, Kimberly; Krammer, Florian; Jhang, Jeffrey S.; Arinsburg, Suzanne A. title: Anti‐SARS‐CoV‐2 Spike Antibodies are Stable in Convalescent Plasma when Stored at 4° Celsius for at Least 6 Weeks date: 2020-08-14 journal: Transfusion DOI: 10.1111/trf.16047 sha: doc_id: 349669 cord_uid: o3eelqcw nan As nations around the world continue to address the public health crisis of Coronavirus Disease 2019 (COVID19), the global medical and scientific communities continue to search for and develop therapeutic strategies for patients. To date, remdesivir presents one such option and can shorten the duration of hospitalization in patients with severe disease 1 . Convalescent plasma (CP) has presented another option, with its use and safety supported by numerous case series and retrospective studies [2] [3] [4] . While its degree of effectiveness has been variable, there is general agreement that it acts as a supportive adjunctive therapy in patients with moderate to severe disease 2,4 . Current CP protocols such as the Mayo Clinic Early Access Program (EAP) specify that once thawed, CP may be stored for up to 5 days at 4˚ Celsius. Presumably, this is intended to mimic current guidelines which apply to thawed plasma (TPL), which specify a similar shelf-life. However, the rationale for this guideline stems from the fact that under normal circumstances, donor plasma is transfused or exchanged therapeutically for the purposes of correcting or preventing a coagulation factor deficiency, to replace deficient factors necessary for hemostatic balance such as ADAMTS13, or to restore complement-regulatory factors in the setting of atypical hemolytic uremic syndrome. For these purposes, TPL is largely considered equivalent to fresh frozen plasma, with the exception of decreases in Factors V and VIII activity levels, and several other components 5, 6 . However, the therapeutic goal of CP transfusion is to deliver passive immunity to the patient via antibodies. Studies demonstrating antibody stability under refrigerated conditions have largely focused on peripheral blood samples stored for several days 7, 8 . However, studies describing the stability of antibodies in refrigerated donor plasma over longer periods are lacking. Here, we demonstrate the long-term stability of anti-SARS-CoV-2 spike antibodies in donor CP samples collected at a local blood donor center for transfusion. After thawing of fifteen CP units, segments were sampled and anti-spike antibody titers were determined via enzyme-linked immunosorbent assays (ELISAs) 9 . Segments from five non-CP units were sampled as a negative control. All samples were then stored at 4˚C, and plasma endpoint titers were reevaluated at 14, 28 and 42 days. We detected no reduction in antibody titers for any of the samples ( Table 1 ). The anti-spike ELISA assay demonstrates a between-run %CV ranging from 6.3% at an antibody concentration of 0.3mcg/ml, to 23% at a concentration of 0.01875 mcg/ml. Therefore, the perceived decrease in titer for most samples between days 1 and 7, and the perceived increase between days 28 and 42 reflects the serial dilution cutoff values of the ELISA assay itself and run-to-run variation, and are not reflective of a true change. This is supported by the results obtained when the area under the curve (AUC) values for raw absorbance data are calculated, and show no significant variation over time ( Figure Accepted Article 1). While our study does not address the neutralization capacity of these antibodies, previous studies demonstrate significant correlation between spike antibody titers and neutralization capacity of plasma and serum samples 9 . We do note that our findings are limited by several factors. First, while limited case series have identified that CP may be effective in reducing morbidity and overall mortality, its efficacy has not been formally evaluated in large randomized clinical trials. Similarly, while there is correlation between spike antibody titers and neutralization capacity, as well as historical basis for the antibodies themselves as This would need to be formally determined by a randomized trial comparing CP to standard frozen plasma. There may also be a slight increase in risk for septic reactions, though we believe this risk remains low, given the estimated incidence of septic reactions from red cell units of 1 in 250,000 -500,000 11 , a product which in some cases is also stored for up to 42 days at 4˚C. Accepted Article This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved. Accepted Article Remdesivir in adults with severe COVID-19: a randomised, doubleblind, placebo-controlled, multicentre trial Treatment of COVID-19 Patients with Convalescent Plasma Early safety indicators of COVID-19 convalescent plasma in 5,000 patients Convalescent plasma treatment of severe COVID-19: A matched control study Evaluation and comparison of coagulation factor activity in fresh-frozen plasma and 24-hour plasma at thaw and after 120 hours of 1 to 6 degrees C storage Comparison and stability of ADAMTS13 activity in therapeutic plasma products Long-term stability of trastuzumab in plasma and whole blood samples stored under different conditions One-month stability study of a biosimilar of infliximab (Remsima((R))) after dilution and storage at 4 degrees C and 25 degrees C A serological assay to detect SARS-CoV-2 seroconversion in humans COVID-19 and its implications for thrombosis and anticoagulation Bacterial contamination of blood components: risks, strategies, and regulation: joint ASH and AABB educational session in transfusion medicine New York, NY 10029 *These authors contributed equally to this work