SARS-COV-2 ANTIBODY LEVELS CONTINUE TO RISE IN IMMUNE GLOBULIN PREPARATIONS

Abstract

<h3>Introduction</h3> We previously published data on SARS-CoV-2 antibody levels in commercial intravenous immune globulin (IVIG) products that were prepared between August 2019 to September 2021 and showed a dramatic increase in antibody levels corresponding with increase in COVID-19 cases and vaccine availability. We continue to report on the longitudinal analysis of SARS-CoV-2 antibody levels in IVIG preparations and have updated data through March 2022. <h3>Methods</h3> IVIG samples are collected from our infusion clinic. IVIG product name, lot number and manufacturing date were recorded. SARS-CoV-2 antibody levels and total immunoglobulin levels were measured using commercially available assays. <h3>Results</h3> No IVIG products manufactured on or before January 2020 had detectable SARS-CoV-2 antibodies. We observed a dramatic increase in SARS-CoV-2 antibody levels that coincided after the availability of COVID-19 vaccines with many levels increasing beyond the upper limit threshold of 2,500 U/mL after February 2021. The commercial laboratory has now expanded the reporting range to an upper limit threshold of 25,000 U/mL. Under the new reporting range, we tested older samples that had exceeded the previous reporting range as well as newer samples. We see a continued rise in SARS-CoV-2 antibodies with levels quickly reaching >25,000 U/mL by October 2021 as the COVID-19 pandemic continues. <h3>Conclusion</h3> SARS-CoV-2 antibody levels in IVIG preparations continue to increase exponentially with case prevalence and increased vaccinations. We are planning to dilute samples to further trend levels beyond the current reporting range. It remains undetermined what level of SARS-CoV-2 antibody correlates to immunity against developing symptomatic disease.