Severe Acute Respiratory Syndrome Coronavirus 2 Neutralizing Antibody Titers in Convalescent Plasma and Recipients in New Mexico: An Open Treatment Study in Patients With Coronavirus Disease 2019

Background. Convalescent plasma (CP) is a potentially important therapy for coronavirus disease 2019 (COVID-19). However, knowledge regarding neutralizing antibody (NAb) titers in donor plasma and their impact in patients with acute COVID-19 remains largely undetermined. We measured NAb titers in CP and in patients with acute COVID-19 before and after transfusion through the traditional Food and Drug Administration investigational new drug pathway. Methods. We performed a single-arm interventional trial measuring NAb and total antibody titers before and after CP transfusion over a 14-day period in hospitalized patients with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 infection. Results. NAb titers in the donor CP units were low (<1:40 to 1:160) and had no effect on recipient neutralizing activity 1 day after transfusion. NAb titers were detected in 6 of 12 patients on enrollment and in 11 of 12 at > 2 time points. Average titers peaked on day 7 and declined toward day 14 (P = .004). Nab titers and immunoglobulin G levels were correlated in donor plasma units (rho = 0.938; P <.001) and in the cumulative patient measures (rho = 0.781; P <.001). Conclusions. CP infusion did not alter recipient NAb titers. Prescreening of CP may be necessary for selecting donors with high titers of neutralizing activity for infusion into patients with COVID-19.