Microbiology Spectrum (Aug 2022)

SARS-CoV-2 Convalescent Sera Binding and Neutralizing Antibody Concentrations Compared with COVID-19 Vaccine Efficacy Estimates against Symptomatic Infection

  • Amy J. Schuh,
  • Panayampalli S. Satheshkumar,
  • Stephanie Dietz,
  • Lara Bull-Otterson,
  • Myrna Charles,
  • Chris Edens,
  • Jefferson M. Jones,
  • Kristina L. Bajema,
  • Kristie E. N. Clarke,
  • L. Clifford McDonald,
  • Sadhna Patel,
  • Kendra Cuffe,
  • Natalie J. Thornburg,
  • Jarad Schiffer,
  • Kelly Chun,
  • Monique Bastidas,
  • Manory Fernando,
  • Christos J. Petropoulos,
  • Terri Wrin,
  • Suqin Cai,
  • Dot Adcock,
  • Deborah Sesok-Pizzini,
  • Stanley Letovsky,
  • Alicia M. Fry,
  • Aron J. Hall,
  • Adi V. Gundlapalli

DOI
https://doi.org/10.1128/spectrum.01247-22
Journal volume & issue
Vol. 10, no. 4

Abstract

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ABSTRACT Previous COVID-19 vaccine efficacy (VE) studies have estimated neutralizing and binding antibody concentrations that correlate with protection from symptomatic infection; how these estimates compare to those generated in response to SARS-CoV-2 infection is unclear. Here, we assessed quantitative neutralizing and binding antibody concentrations using standardized SARS-CoV-2 assays on 3,067 serum specimens collected during 27 July 2020 to 27 August 2020 from COVID-19-unvaccinated persons with detectable anti-SARS-CoV-2 antibodies. Neutralizing and binding antibody concentrations were severalfold lower in the unvaccinated study population compared to published concentrations at 28 days postvaccination. In this convenience sample, ~88% of neutralizing and ~63 to 86% of binding antibody concentrations met or exceeded concentrations associated with 70% COVID-19 VE against symptomatic infection; ~30% of neutralizing and 1 to 14% of binding antibody concentrations met or exceeded concentrations associated with 90% COVID-19 VE. Our study not only supports observations of infection-induced immunity and current recommendations for vaccination postinfection to maximize protection against COVID-19, but also provides a large data set of pre-COVID-19 vaccination anti-SARS-CoV-2 antibody concentrations that will serve as an important comparator in the current setting of vaccine-induced and hybrid immunity. As new SARS-CoV-2 variants emerge and displace circulating virus strains, we recommend that standardized binding antibody assays that include spike protein-based antigens be utilized to estimate antibody concentrations correlated with protection from COVID-19. These estimates will be helpful in informing public health guidance, such as the need for additional COVID-19 vaccine booster doses to prevent symptomatic infection. IMPORTANCE Although COVID-19 vaccine efficacy (VE) studies have estimated antibody concentrations that correlate with protection from COVID-19, how these estimates compare to those generated in response to SARS-CoV-2 infection is unclear. We assessed quantitative neutralizing and binding antibody concentrations using standardized assays on serum specimens collected from COVID-19-unvaccinated persons with detectable antibodies. We found that most unvaccinated persons with qualitative antibody evidence of prior infection had quantitative antibody concentrations that met or exceeded concentrations associated with 70% VE against COVID-19. However, only a small proportion had antibody concentrations that met or exceeded concentrations associated with 90% VE, suggesting that persons with prior COVID-19 would benefit from vaccination to maximize protective antibody concentrations against COVID-19.

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