{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,26]],"date-time":"2026-10-26T23:17:56Z","timestamp":1793056676561,"version":"4.5.0"},"reference-count":41,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2025,6,4]],"date-time":"2025-06-04T00:00:00Z","timestamp":1748995200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000060","name":"National Institute of Allergy and 49 Infectious Diseases","doi-asserted-by":"crossref","award":["50 75N93019C00052"],"award-info":[{"award-number":["50 75N93019C00052"]}],"id":[{"id":"10.13039\/100000060","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/100008065","name":"Georgia Research Alliance","doi-asserted-by":"crossref","award":["GRA51 001"],"award-info":[{"award-number":["GRA51 001"]}],"id":[{"id":"10.13039\/100008065","id-type":"DOI","asserted-by":"crossref"}]},{"name":"National Center for Advancing Translational Sciences of the National Institutes of Health","award":["UL1TR002378"],"award-info":[{"award-number":["UL1TR002378"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background\/Objectives: To evaluate how immune responses compare among ethnic groups approximately 2 years after receiving a third dose of COVID-19 vaccine (BNT162b2, mRNA-1273, ChAdOx1or BBIBP-CorV), we tested T cell responses and Spike-specific RBD-antibody titer, and neutralized antibody titer levels utilizing Spectral Flow cytometry, ELISA, and SARS-CoV-2 pseudotyped-based neutralization assays, respectively. Methods: Forty-four individuals from January\u2013December 2023 were identified within the cohort and were classified into different ethnic backgrounds; Black (N = 13), Asian (N = 14), Caucasian (N = 17). We recognize that the \u201cAsian\u201d group includes diverse subpopulations with distinct genetic and environmental backgrounds, which could not be further stratified due to sample-size limitations. Spike-specific AIM+, CD4+, and CD8+ T cell responses were assessed and evaluated against SARS-CoV-2 variants, including the ancestral Wuhan, Delta, and multiple Omicron subvariants (B1.1529, BA2.86, BA.4\/5, and XBB.1). Alongside we tested the RBD-IgG and neutralizing antibody titers against the ancestral Wuhan. Spearman\u2019s correlation analysis was utilized to determine corelative relationships among the AIM+ and CD4+ T cell responses, as well as the RBD-IgG and neutralizing antibody titers. Results: Our results show robust and comparable RBD-IgG and neutralizing antibody titers across all groups, with a significant positive correlation between these two measurements. Significant differences were observed in T-cell activation, with Asian participants exhibiting lower frequencies of Spike-specific CD4+ T cells against SARS-CoV-2 Omicron subvariants and higher frequencies of cytokine-producing CD4+ T cells (TNF-\u03b1, IFN-\u03b3, and IL-2) as compared to the Caucasian group. Breakthrough infection status was not fully controlled and may influence these findings. Conclusion: Despite a small sample size and potential confounding by natural infections within our long-time-span sampling, our data suggest persistent cellular and humoral immunity 2 years after vaccination across ethnicities, with notable differences in T cell activation and cytokine profile. These preliminary observations highlight the need for larger, more detailed studies that consider intra-ethnic diversity and hybrid immunity to better understand ethnic differences in COVID-19 vaccine responses.<\/jats:p>","DOI":"10.3390\/vaccines13060607","type":"journal-article","created":{"date-parts":[[2025,6,4]],"date-time":"2025-06-04T11:14:12Z","timestamp":1749035652000},"page":"607","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Ethnic Comparisons of Spike-Specific CD4+ T Cells, Serological Responses, and Neutralizing Antibody Titers Against SARS-CoV-2 Variants"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1767-7248","authenticated-orcid":false,"given":"Fani","family":"Pantouli","sequence":"first","affiliation":[{"name":"Florida Research and Innovation Center, Cleveland Clinic, 9801 SW Discovery Way, Port Saint Lucie, FL 34987, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2991-7210","authenticated-orcid":false,"given":"Vanessa","family":"Silva-Moraes","sequence":"additional","affiliation":[{"name":"Florida Research and Innovation Center, Cleveland Clinic, 9801 SW Discovery Way, Port Saint Lucie, FL 34987, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1947-7469","authenticated-orcid":false,"given":"Ted","family":"Ross","sequence":"additional","affiliation":[{"name":"Florida Research and Innovation Center, Cleveland Clinic, 9801 SW Discovery Way, Port Saint Lucie, FL 34987, USA"},{"name":"Department of Infection Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA"},{"name":"Center for Vaccines and Immunology, University of Georgia, Athens, GA 30602, USA"},{"name":"Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"7954","DOI":"10.1038\/s41467-024-52348-9","article-title":"Omicron COVID-19 immune correlates analysis of a third dose of mRNA-1273 in the COVE trial","volume":"15","author":"Zhang","year":"2024","journal-title":"Nat. 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