Analysis of 52 240 source plasma donors of convalescent COVID-19 plasma: Sex, ethnicity, and age association with initial antibody levels and rate of dissipation

Abstract

Background: COVID-19 convalescent plasma (CCP) was approved under emergency authorization to treat critically ill patients with COVID-19 in the United States in 2020. We explored the demographics of donors contributing plasma for a hyperimmune, plasma-derived therapy to evaluate factors that may be associated with anti-SARS-CoV-2 antibody response variability and, subsequently, antibody titers.

Study design: An electronic search of CCP donors was performed across 282 US plasma donation centers. Donations were screened for nucleocapsid protein-binding-IgG using the Abbott SARS-CoV-2 IgG assay.

Results: Overall, 52 240 donors donated 418 046 units of CCP. Donors were of various ethnicities: 43% Caucasian, 34% Hispanic, 17% African American, 2% Native American, 1% Asian, and 3% other. Females had higher initial mean anti-SARS-CoV-2 antibody titers but an overall faster rate of decline (P < .0001). Initial antibody titers increased with age: individuals aged 55 to 66 years had elevated anti-SARS-CoV-2 titers for longer periods compared with other ages (P = .0004). African American donors had the lowest initial antibody titers but a slower rate of decline (P < .0001), while Caucasian (P = .0088) and Hispanic (P = .0193) groups had the fastest rates of decline. Most donor antibody levels decreased below the inclusion criteria (≥1.50) within 30 to 100 days of first donation, but donation frequency did not appear to be associated with rate of decline.

Conclusion: Several factors may be associated with anti-SARS-CoV-2 antibody response including donor age and sex. Evaluating these factors during development of future hyperimmune globulin products may help generation of therapies with optimal efficacy.

Keywords: SARS-CoV-2; convalescent COVID-19 plasma; hyperimmune globulins; plasma donor demographics.

FIGURE 1

Anti‐SARS‐CoV‐2 antibody levels and sex. (A) Distribution of mean initial anti‐SARS‐CoV‐2 titers by sex. Anti‐SARS‐CoV‐2 antibody levels (S/C ratio) were determined by the Abbott assay (x‐axis), with an S/C of <1.40 indicating negativity. The y‐axis represents the relative frequency (density) of donors. (B) Change in anti‐SARS‐CoV‐2 antibody titers per day by sex. The x‐axis shows the change in anti‐SARS‐CoV‐2 antibody levels and the y‐axis represents donor density. (C) Change in anti‐SARS‐CoV‐2 titer per day by initial titer range and sex

FIGURE 2

Anti‐SARS‐CoV‐2 antibody levels and age. (A) Distribution of initial anti‐SARS‐CoV‐2 titers by age. Anti‐SARS‐CoV‐2 antibody levels (S/C ratio) were determined by the Abbott assay (x‐axis), with an S/C of <1.40 indicating negative titers. The y‐axis represents the relative frequency (density) of donors. (B) Time until anti‐SARS‐CoV‐2 antibody titer drops to <1.50 by age

FIGURE 3

Temporal evolution of anti‐SARS‐CoV‐2 antibody levels. (A) Change of anti‐SARS‐CoV‐2 titer over time relative to the first donation and out to 120 days after the first donation. Assessing titers beyond 120 days resulted in a significant reduction in donor numbers and thus too small a cohort for meaningful analyses. The distribution of the change in anti‐SARS‐CoV‐2 titer across the donor population is displayed by quantiles, with the inner 98% of the distribution shaded in light blue and the central 50% in darker blue. (B) The number of donors with donations after X days since the first donation