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Publications

Journal Article Epublish

PubMed: 40416973 DOI: 10.3389/fimmu.2025.1596065

Reduced immune response to SARS-CoV-2 infection in the elderly after 6 months.

Front Immunol 16:1596065

Authors: Qin Luo, Qinqin Song, Yan Li, Kexin Zong, Ti Liu, Junming He, Guoyong Mei, Haijun Du, Zhiqiang Xia, Mi Liu, Juan Song, Chen Gao, Dong Xia, Guangyu Xue, Wenyan Tian, Yinli Qu, Zengqiang Kou, Zhongjun Dong, Jun Han

Affiliations

  • National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
  • Shandong Center for Disease Control and Prevention, Shandong Provincial Key Laboratory of Intelligent Monitoring, Early Warning, and Prevention and Control of Infectious Diseases, Shandong Institute of Preventive Medicine, Jinan, China.
  • Department of Infectious Diseases, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
  • Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China.
  • The First Affiliated Hospital of Anhui Medical University and Institute of Clinical Immunology, Anhui Medical University, Hefei, China. State Key Laboratory of Membrane Biology, School of Medicine and Institute for Immunology, Tsinghua University, Beijing, China.

Abstract

Objectives

To evaluate the immune persistence and cross-immune response of elderly individuals after Omicron BA.5 infections.

Method

The neutralizing antibodies against WT, BA.5, XBB.1 and EG.5 strains were analyzed. The T/B-cell subsets' responses were tested through intracellular cytokine staining and flow cytometry.

Results

The neutralizing antibodies titers against WT and BA.5 strain, remaining high level for at least 6 months, were higher than that of both XBB.1 and EG.5 variants. The neutralizing antibodies of WT, BA.5, XBB.1, and EG.5 strains in the elderly were slightly lower than those in middle-age. The memory B cells decreased rapidly in the elderly, and Tfh, Th17 cells of the elderly continued to increase for only 3 months, while Tfh and Th17 cells increased in the middle-aged for over 6 months. For the elderly, after peptide stimulation, unswitched/switched memory B cells decreased, while double negative B cells displayed higher proliferation. The proportions of both naïve and Temra cells in CD4 + and CD8 + T cells declined, whereas those of Tcm and Tem cells elevated. In the meantime, both CD69 + and CD38 + T cells decreased, but the frequencies of PD-1 + and CTLA-4 + of CD4 + and CD8 + T cells showed an increasing trend. The proportions of PD-1 + and CTLA-4 + cells also increased in older people with long COVID symptoms at 3m post-infection.

Conclusions

Omicron BA.5 infection induced lower neutralizing antibodies against XBB.1 and EG.5 variant. The decrease of memory B cells, CD69 + and CD38 +T cells, as well as the increase of PD-1 +, CTLA-4 + of CD4 +/CD8 +T cells and double negative B cells, indicate that sustained immune responses against BA.5 infection may wane more rapidly in elderly populations.

MeSH

Cells, Sars-Cov-2, Antibodies, Adaptive Immunity, Antibodies, Neutralizing, Aged, Covid-19, Immune System Diseases, Immunity, Severe Acute Respiratory Syndrome-Related Coronavirus, Memory, B-Lymphocytes, Infections