Background: Pertussis remains a health problem among infants and children under-five despite the ongoing Diphtheria–Tetanus-Pertussis (DTP) immunization program. Objective: To assess the association between DPT immunization status and PCR-confirmed pertussis among infants and children under-five in Palembang City, 2023–2025.Methods: A test-negative design study was conducted using secondary…