Correlation Between Postvaccination Anti-Spike Antibody Titers and Protection Against Breakthrough Severe Acute Respiratory Syndrome Coronavirus 2 Infection: A Population-Based Longitudinal Study.

In this population-based cohort of 7538 adults, combined immunoglobulin (Ig) G, IgA, and IgM (IgG/A/M) anti-spike titers measured after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination were predictive of protection against breakthrough SARS-CoV-2 infection. Discrimination was significantly improved by adjustment for factors influencing risk of SARS-CoV-2 exposure, including household overcrowding, public transport use, and visits to indoor public places. Anti-spike IgG/A/M titers showed positive correlation with neutralizing antibody titers (rs = 0.80 [95% confidence interval, .72-.86]; P < .001) and S peptide-stimulated interferon-γ concentrations (rs = 0.31 [.13-.47]; P < .001).
Competing Interests: Potential conflicts of interest. A. R. M. declares receipt of funding, outside the submitted work, to support vitamin D research from the following companies, which manufacture or sell vitamin D supplements: Pharma Nord, DSM Nutritional Products, Thornton & Ross, and Hyphens Pharma. A. R. M. also declares the following, all outside the submitted work: receipt of funding from the Karl R Pfleger Foundation, the AIM Foundation, the UK National Institute for Health Research Clinical Research Network, Warburtons, and Matthew Isaacs; consulting fees from DSM Nutritional Products and payment from Oregon State University for lectures, presentations, speakers bureaus, manuscript writing, or educational events; support for attending meetings from Pharma Nord and Abiogen Pharma; participation on the data and safety monitoring board for the VITALITY trial (VITamin D for AdoLescents with HIV to reduce musculoskeletal morbidity and ImmunopaThologY); unpaid work as a program committee member for the Vitamin D Workshop; and receipt of vitamin D capsules for clinical trial use from Pharma Nord, Synergy Biologics, and Cytoplan. E. S. C. declares receipt of an honorarium from UCB Pharma for lectures, outside the submitted work, and is an Early Career Trustee for the British Society for Immunology. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
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