SARS-CoV-2 Antibody Longitudinal Profile of Immune Globulin Preparations

Introduction: Intravenous immunoglobulin (IVIG) preparations, used for the treatment of antibody deficiencies, provide a glimpse of the general population’s antibody profile as each preparation is generated from a pool of thousands of donors. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the coronavirus disease 2019 (Covid-19) pandemic, and a vaccine for the prevention of Covid-19 was authorized for emergency use in December 2020. We completed a longitudinal analysis of SARS-CoV-2 antibody levels in commercial IVIG preparations. Materials and Methods: We collected IVIG samples from our infusion clinic. IVIG product lot number, product name, and manufacturer information were recorded, with the date of preparation verified from the manufacturer. SARS-CoV-2 antibody titers as well as total immunoglobulin levels were measured using commercially available assays. The study received Institutional Review Board approval. Results: We found no SARS-CoV-2 antibodies in preparations generated on or before January 2020. Overall, SARS-CoV-2 antibody levels in IVIG preparations tended to increase with progressing preparation date. We observed a dramatic and continual rise of SARS-CoV-2 antibody levels in IVIG preparations made in the beginning after January 2021, coinciding with the peak in incidence of confirmed cases and availability of Covid-19 vaccines in the United States. Conclusion: SARS-CoV-2 antibody levels in IVIG mirror case prevalence, and vaccination resulted in a far more rapid rate of rise in antibody levels. IVIG preparations or serum repositories can provide an accessible way to model a population’s evolving novel pathogen exposure, immunity, and vaccine response.