Longitudinal antibody titer, avidity, and neutralizing responses after SARS-CoV-2 infection

Jonathon M. Monroe, Iana H. Haralambieva, Nathaniel D. Warner, Diane E. Grill, Huy Quang Quach, Richard B. Kennedy

Research output: Contribution to journalArticlepeer-review


While waning immunity and SARS-CoV-2 variant immune escape continue to result in high infection rates worldwide, associations between longitudinal quantitative, qualitative, and functional humoral immune responses after SARS-CoV-2 infection remain unclear. In this study, we found significant waning of antibody against Spike S1 (R = −0.32, p = 0.035) and N protein (R = −0.39, p = 0.008), while RBD antibody moderately decreased (R = −0.19, p = 0.203). Likewise, neutralizing antibody titer (ND50) waned over time (R = −0.46, p = 0.001). In contrast, antibody avidity increased significantly over time for Spike S1 (R = 0.62, p = 6.0e−06), RBD (R = 0.54, p = 2.0e−04), and N (R = 0.33, p = 0.025) antibodies. Across all humoral responses, ND50 strongly associated with Spike S1 (R = 0.85, p = 2.7e−13) and RBD (R = 0.78, p = 2.9e−10) antibodies. Our findings provide longitudinal insight into humoral immune responses after infection and imply the potential of Spike S1/RBD antibody titer as surrogate correlates of protection.

Original languageEnglish (US)
Article numbere11676
Issue number11
StatePublished - Nov 2022


  • Antibody avidity
  • COVID-19
  • Humoral immunity
  • Longitudinal immunity
  • Neutralization
  • SARS-CoV-2

ASJC Scopus subject areas

  • General


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