Vaccination, infection, and hybrid immunity: determinants of SARS-CoV-2 IgG antibody levels and protection in Quzhou, China

Vaccination, infection, and hybrid immunity: determinants of SARS-CoV-2 IgG antibody levels and protection in Quzhou, China

ObjectivesTo investigate the factors influencing SARS-CoV-2 IgG antibody levels and protection in a population that has experienced both vaccination and COVID-19 infections, predominantly caused by the Omicron BA.5.2 and BF.7 variants.MethodsAnti-SARS-CoV-2 IgG antibody levels were measured using ch...

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Bibliographic Details
Main Authors: Zhiying Yin, Mengcheng Yin, Fei Zhao, Canya Fu, Wenjie Xu, Quanjun Fang, Xiaoying Gong, Guoping Cao, Canjie Zheng
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-07-01
Series:Frontiers in Immunology
Subjects:
COVID-19
SARS-CoV-2
vaccination
infection
hybrid immunity
Online Access:https://www.frontiersin.org/articles/10.3389/fimmu.2025.1576016/full
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Summary:ObjectivesTo investigate the factors influencing SARS-CoV-2 IgG antibody levels and protection in a population that has experienced both vaccination and COVID-19 infections, predominantly caused by the Omicron BA.5.2 and BF.7 variants.MethodsAnti-SARS-CoV-2 IgG antibody levels were measured using chemiluminescent microparticle immunoassay (CMIA). Multivariate regression analyses assessed factors influencing antibody levels, and decision tree models predicted variable priorities.ResultsAmong the 3494 participants, the median (IQR) anti-SARS-CoV-2 IgG level was 396.53 (280.51–471.03) AU/mL, with a seropositive rate of 97.28%. Multivariate analysis revealed that vaccination status, infection status, residence county, occupation, and vaccination interval were significantly associated with antibody concentration. The decision tree model indicated that vaccination had a greater effect on antibody concentration than infection, while infection had a stronger impact on seropositivity. The Breakthrough Infection group had the highest antibody concentration compared with other groups.ConclusionsVaccination and infection were identified as the primary determinants of SARS-CoV-2 IgG antibody levels, with hybrid immunity significantly enhancing antibody responses. New evaluation methods or revised detection thresholds were needed to better assess population immunity.
ISSN:1664-3224

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