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

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.

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.

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.

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.