Rapidly Increasing SARS-CoV-2 Neutralization by Intravenous Immunoglobulins Produced from Plasma Collected During the 2020 Pandemic

Immunoglobulin (IG) lots (N=176) released since March 2020 were tested for SARS-CoV-2 neutralizing antibodies, with first positive results for September 2020 lots, mean = 1.8 IU/ml, 46% of lots positive. From there, values steadily increased, in correlation with the cumulative COVID-19 incidence, to reach a mean of 36.7 IU/ml and 93% of lots positive by January 2021. Extrapolating the correlation, IGs could reach an anti-SARS-CoV-2 potency of ~400 IU/ml by July 2021. At that stage, prophylactic IG treatment for primary/secondary immunodeficiency could contain similar doses of anti-SARS-CoV-2 as convalescent plasma which is used for treatment of COVID-19.