Neutralizing Antibody Response Characteristics in Elderly Patients with SARS-CoV-2 Infection and Their Association with Clinical Phenotypes

<b>Background/Objectives</b>: Although SARS-CoV-2 infection often follows a self-limiting course, its public health impact remains persistent. Older adults exhibit unique susceptibility to infection due to immunosenescence. Therefore, in order to offer recommendations for improving management options for older persons, this study intends to examine the immunological properties of NAb in the elderly population. <b>Methods</b>: Elderly patients aged 60 years and older infected during the prevalence of BF.7 and EG.5 variants were enrolled. The patterns of NAb responses in infected patients under both natural and vaccine-induced immunity were explored using bead-based proteomics techniques. The associations between NAb and IgG antibody levels, clinical characteristics, and traditional inflammatory indicators were evaluated using systematic analysis. Based on NAb levels, SARS-CoV-2 strains were immunologically classified. <b>Results</b>: There was a positive correlation between the severity of the disease and the strength of the NAb response. Because of more extensive immune activation, severe instances in elderly patients showed higher levels of NAb responses. When compared to the uninfected group, people who had received two doses of vaccination exhibited greater NAb levels. Additionally, there was a link between NAb and IgG levels, but as the virus evolved, this correlation progressively diminished. Three serotypes of SARS-CoV-2 were identified based on NAb response characteristics: pre-Omicron, Omicron, and XBB serotypes. <b>Conclusions</b>: The results show the features of NAb responses in older patients, which could help with the creation of future vaccines and public health initiatives.