Low Antibody Titers Demonstrate Significantly Increased Rate of SARS-CoV-2 Infection in a Highly Vaccinated Population from the National Basketball Association

Abstract

SARS-CoV-2 antibody titers may serve as a correlate for immunity and could inform optimal booster timing. The relationship between antibody titer and protection from infection was evaluated in 2,323 vaccinated individuals from the National Basketball Association who had antibody levels measured from 9/12/2021 to 12/31/2021. Cox-proportional hazards models were used to estimate risk of infection within 90-days of serologic testing by titer level (<250, 250-800, and >800 AU/mL) and individuals were censored on date of booster receipt. The cohort was 78.2% male, 68.1% aged ≤ 40 years, and 56.4% vaccinated (primary series) with the Pfizer-BioNTech mRNA vaccine. Among the 2,248 individuals not yet boosted at testing, those with titers <250 AU/mL (adj HR: 2.4; 95% CI: 1.5, 3.7) and 250-800 800 AU/mL (adj HR: 1.5; 95% CI: 0.98, 2.4) had greater infection risk compared to those with titers >800 AU/mL. Serologic titers could inform individual COVID-19 risk and booster scheduling.

IgG and IgM differentiation in a particle-based agglutination assay by control over antigen surface density

“…12,13 However, LFIA is limited in sensitivity and fails to provide a quantitative assessment of the detected analyte, which is essential for testing the efficiency of vaccines against new variants and correlating antibody levels to immunity against COVID-19 infection. [14][15][16] Enzyme-linked immunosorbent assay (ELISA) serves as a compelling alternative to LFIA, offering enhanced quantitative diagnostic capabilities characterized by superior sensitivity and a broader dynamic range. 17,18 However, ELISA demands a longer time for result generation, specialized training, and laboratory expertise for proficient execution, and lacks decentralization.…”