Trajectory Patterns of Hygiene Training Effectiveness Across Three Instructional Modes

<b>Background:</b> Hygiene and food-safety training is a critical public health strategy for preventing contamination and promoting safe food-handling practices in community settings. This study evaluated the long-term effectiveness of In-person, Online, and Hybrid instructional modes in enhancing hygiene and food-safety competencies among trainees in Ilocos Norte, Philippines. <b>Methods:</b> Using a longitudinal quasi-experimental design, performance was measured at 12, 24, and 36 months across four domains: Personal Health & Hygiene, Food Hazards, Cleaning and Sanitation, and Good Manufacturing Practices. A total of 384 students met all inclusion criteria and completed the full series of evaluations. Descriptive and inferential statistical analyses were employed. <b>Results:</b> Competency scores increased significantly over time in all instructional modes (<i>p</i> < 0.001). Hybrid learners demonstrated the highest early longitudinal gains at 12 months (mean score, <i>M</i> = 20.88), compared with In-person (<i>M</i> = 10.28) and Online (<i>M</i> = 10.57). At 36 months, Online learners achieved the highest performance (<i>M</i> = 19.50), indicating stronger long-term retention. Effect size analysis using eta squared (η²) showed large effects for Cleaning and Sanitation (η² = 0.196), Good Manufacturing Practices (η² = 0.115), and overall performance (η² = 0.138). Standardized Mean Change (SMC) indicated substantial improvement across modes, with Hybrid showing the greatest early change (SMC = 41.76 at 12 months) and Online exhibiting the strongest long-term improvement (SMC = 38.80 at 36 months). Training Efficiency Index (TEI) identified In-person instruction as most efficient (TEI = 30.55), followed by Online (29.49) and Hybrid (19.56). Linear Mixed-Effects Regression confirmed significant main effects of Time (β = 4.82, <i>p</i> < 0.001) and Mode (β = 3.97, <i>p</i> < 0.001), as well as a significant Time × Mode interaction (β = −1.42, <i>p</i> < 0.01). <b>Conclusions:</b> The findings indicate that Hybrid instruction supports rapid early competency gains, while Online instruction yields superior long-term mastery of hygiene and food-safety competencies. These results provide evidence-based guidance for optimizing hygiene training programs in community and public health contexts.