Kinetics of SARS-CoV-2 Serum Antibodies Through the Alpha, Delta, and Omicron Surges Among Vaccinated Health Care Workers at a Boston Hospital

Maura C Dodge; Lei Ye; Elizabeth R Duffy; Manisha Cole; Susan H Gawel; Martha M Werler; David Daghfal; Chris Andry; Yachana Kataria

doi:10.1093/ofid/ofad266

Kinetics of SARS-CoV-2 Serum Antibodies Through the Alpha, Delta, and Omicron Surges Among Vaccinated Health Care Workers at a Boston Hospital

Open Forum Infect Dis. 2023 May 17;10(7):ofad266. doi: 10.1093/ofid/ofad266. eCollection 2023 Jul.

Authors

Maura C Dodge¹, Lei Ye², Elizabeth R Duffy³, Manisha Cole³, Susan H Gawel², Martha M Werler⁴, David Daghfal², Chris Andry^{1

3}, Yachana Kataria^{1

3}

Affiliations

¹ Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston, Massachusetts, USA.
² Department of Biostatistics, Abbott Core Diagnostics, Abbott Park, Illinois, USA.
³ Department of Pathology and Laboratory Medicine, Chobanian and Avedisian School of Medicine, Boston University, Boston, Massachusetts, USA.
⁴ Department of Epidemiology, School of Public Health, Boston University, Boston, Massachusetts, USA.

Abstract

Background: Longitudinal serology studies can assist in analyzing the kinetics of antibodies to SARS-CoV-2, helping to inform public health decision making. Our study aims to characterize circulating antibody trends over 18 months in vaccinated participants with and without evidence of COVID-19 infection.

Methods: A cohort of health care workers employed at Boston Medical Center was followed to collect serum samples and survey data over 6 time points from July 2020 through December 2021 (N = 527). History of SARS-CoV-2 infection, vaccination, and booster status were confirmed, where possible, through electronic medical records. Serum was assessed for the qualitative and semiquantitative detection of IgG antibody levels (anti-nucleoprotein [anti-N] and anti-spike [anti-S], respectively). Piecewise regression models were utilized to characterize antibody kinetics over time.

Results: Anti-S IgG titers remained above the positivity threshold following infection and/or vaccination throughout the 18-month follow-up. Among participants with no evidence of COVID-19 infection, titers declined significantly faster in the initial 90 days after full vaccination (β = -0.056) from December 2020 to March 2021 as compared with the decline observed following booster dose uptake (β = -0.023, P < 0.001). Additionally, COVID-19 infection prior to vaccination significantly attenuated the decline of anti-S IgG when compared with no infection following vaccine uptake (P < 0.001). Lastly, fewer participants contracted Omicron when boosted (12.7%) compared to fully vaccinated (17.6%). Regardless of vaccination status, participants who were Omicron positive had lower anti-S IgG titers than those who did not test positive, but this difference was not significant.

Conclusions: These findings provide novel 18-month kinetics of anti-S IgG antibodies and highlight the durability of hybrid immunity, underlining the strong humoral response stimulated by combined infection and vaccination.

Keywords: COVID-19; SARS-CoV-2; antibodies; immunity; vaccines.