Key result
Vaccinated individuals with low SARS-CoV-2 antibody titers (<250 AU/mL) had a significantly increased rate of incident infection compared to those with high titers (>800 AU/mL) (adj HR 2.4).
Why the study?
SARS-CoV-2 antibody titers may serve as a correlate for immunity and could inform optimal booster timing.
Do lower SARS-CoV-2 antibody titers increase the risk of incident SARS-CoV-2 infection in vaccinated adults?
Cohort (n=2,323)
Do lower SARS-CoV-2 antibody titers increase the risk of incident SARS-CoV-2 infection in vaccinated adults?
Hazard Ratio: 2.4 (95% CI 1.5–3.7)
Absolute Event Rate: 5.5% vs 8.6%
Lower SARS-CoV-2 antibody titers are associated with a significantly increased risk of subsequent infection, suggesting that serologic testing could inform individualized booster scheduling.
May inform titer-guided boosting in high-exposure vaccinated groups; leaves open generalizability and optimal thresholds.
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—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.
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Tai et al. (2023) conducted a cohort in SARS-CoV-2 infection (n=2,323). Low SARS-CoV-2 antibody titers (<250 AU/mL) vs. High antibody titers (>800 AU/mL) was evaluated on Incident SARS-CoV-2 infection within 90 days following antibody measurement (adj HR 2.4, 95% CI 1.5-3.7). Vaccinated individuals with low SARS-CoV-2 antibody titers (<250 AU/mL) had a significantly increased rate of incident infection compared to those with high titers (>800 AU/mL) (adj HR 2.4).
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