Stimulating T cells with SARS-CoV-2 (Spike Protein) Omicron XBB.1.5.X Mutation peptide pool releases downstream cytokines and upregulates activation markers, enabling antigen-specific T cells to be detected or isolated for analysis. This pool is provided as two lyophilized mixtures (subpools) from the spike glycoprotein of SARS-CoV-2 Omicron XBB.1.5.X subvariant. The subpools contain 158 and 157 peptides, respectively, for a total of 315 peptides, and consist of 15-mer peptides with 11-amino-acid overlaps that cover amino acids 1 to 1269 on the spike protein. Through interactions with the angiotensin-converting enzyme 2 (ACE2) receptor, the spike protein enables the virus to attach to the cell membrane, and plays a critical role in viral entry (Hoffmann et al.; Walls et al.). Viral peptide pools are useful for a broad range of applications, including vaccine development, immunological research, and diagnostic assay development.