ORIGINAL RESEARCH article

Front. Immunol.

Sec. Viral Immunology

Volume 16 - 2025 | doi: 10.3389/fimmu.2025.1576016

This article is part of the Research TopicMathematical Modeling in Discovery and Analysis of Immune ResponsesView all 9 articles

Vaccination, Infection, and Hybrid Immunity: Determinants of SARS-CoV-2 IgG Antibody Levels and Protection in Quzhou, China

Provisionally accepted
Zhiying YinZhiying Yin1*Mengcheng YinMengcheng Yin2Fei ZhaoFei Zhao3Canya FuCanya Fu3Wenjie XuWenjie Xu1Quanjun FangQuanjun Fang1Xiaoying GongXiaoying Gong1Guoping CaoGuoping Cao1Zheng CanjieZheng Canjie1
  • 1Quzhou Center for Disease Control and Prevention, Quzhou, China
  • 2Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
  • 3School of Public Health, Zhejiang Chinese Medical University, Hangzhou, Jiangsu Province, China

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Objectives: To 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.Methods: Anti-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.Results: Among 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.Vaccination 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.

Keywords: COVID-19, SARS-CoV-2, Vaccination, Infection, Hybrid Immunity Region 1414560 0.07 0.15 0.70

Received: 13 Feb 2025; Accepted: 30 Jun 2025.

Copyright: © 2025 Yin, Yin, Zhao, Fu, Xu, Fang, Gong, Cao and Canjie. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Zhiying Yin, Quzhou Center for Disease Control and Prevention, Quzhou, China

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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