Vaccine development increasingly relies on precision antigen selection: instead of using a whole pathogen or a full-length protein, researchers can focus immune responses on carefully chosen antigen epitopes—the specific parts of an antigen that B cells and T cells recognize. This strategy underpins peptide vaccines (and multi-epitope constructs), where short synthetic sequences are selected, optimized, and formulated to drive protective immunity while reducing unnecessary or reactogenic components. In modern pipelines, epitope screening acts as the bridge between basic immunology and engineering-style vaccine design. 1) What “Epitope Screening” Means in Vaccine Development An epitope is a minimal molecular “handle” from an antigen that immune receptors can recognize. Epitope screening aims to identify epitopes that are: Immunogenic (able to elicit a measurable immune response) Relevant to protection (correlated with neutralization, clearance, or T cell control) Conserved (less likely to mutate and escape) Safe (low risk of off-target reactivity or adverse immunopathology) Broadly coverable across populations (especially for T-cell epitopes that depend on HLA/MHC diversity) As vaccine programs move from exploratory research into preclinical assessment, selecting the right antigen targets—including epitope-level targets—becomes a foundational decision that influences downstream formulation, assay development, and clinical strategy. 2) Why Peptide Vaccines Depend on…