Assessing hand-hygiene practices and infectious disease outcomes in preschools: Study protocol

Background: Paediatric infectious diseases are a significant public health concern, particularly in preschools where close contact, shared resources and immature immunity facilitate rapid transmission of respiratory and gastrointestinal pathogens. Hand hygiene (HH) is a cornerstone of infection prevention, yet Australian data on baseline practices, compliance and context-specific intervention feasibility remain limited. Aim: To evaluate the effectiveness of structured, staged HH interventions in reducing infectious disease burden among preschool-aged children. Methods: This two-phase study comprises a 12-week observational baseline assessment followed by a 12-month stepped-wedge cluster randomised controlled trial (SW-cRCT) across 20–30 preschools. Observations will quantify HH compliance at four key moments (after toilet use, before meals, after outdoor play and upon arrival), baseline infection incidence and absenteeism. The SW-cRCT will sequentially implement staged interventions targeting these moments across five periods, with all clusters contributing both control and intervention data. Outcomes include respiratory and gastrointestinal infections, HH compliance, adverse events and intra-cluster correlation coefficients to inform sample size calculations. Data will be collected via structured observations, parent and staff reports, environmental assessments and fidelity monitoring. Mixed-effect regression models will evaluate intervention effects, accounting for cluster-level correlation and temporal trends. Expected results: Structured HH interventions are hypothesised to increase compliance, reduce infection incidence and be feasible, acceptable and cost-effective in preschool settings. Baseline observations will provide critical data for intervention optimisation and trial design. Trial registration: Australian and New Zealand Clinical Trials Registry (ANZCTR); registration number