Promoting hand hygiene during the COVID-19 pandemic: A parallel randomized trial for the optimization of the Soapp app (Preprint)

BACKGROUND Hand hygiene is an effective behavior for preventing the spread of the respiratory disease COVID-19, and was included in public health guidelines worldwide. Behavior change interventions addressing hand hygiene have the potential to support the adherence to public health recommendations and thereby prevent the spread of COVID-19. However, randomized trials during a pandemic are largely absent, wherefore there is little knowledge about the most effective strategies to promote hand hygiene during an ongoing pandemic. The present study addresses this gap by presenting the results of the optimization phase of a Multiphase Optimization Strategy of Soapp, a smartphone app to promote hand hygiene in the context of the COVID-19 pandemic. OBJECTIVE The goal was to identify the most effective combination and sequence of three theory- and evidence-based intervention modules (Habit, Motivation, Social Norms) to promote hand hygiene. To this aim, nine versions of Soapp were developed (conditions) and two optimization criteria were defined: i) condition with largest increase in hand hygiene at follow-up and ii) condition with highest engagement, usability and satisfaction based on quantitative and qualitative analyses. METHODS The study design was a parallel randomized trial with nine intervention conditions defined by the combination of two intervention modules and their sequence. The trial was conducted from March to August 2021 with interested participants of the Swiss general population (N = 232 randomized). Randomization was performed by Qualtrics and blinding was ensured. The duration of the intervention was 34 days. The primary outcome was self-reported hand hygiene at follow-up, assessed via an electronic diary. Secondary outcomes were user engagement, usability and satisfaction, assessed at follow-up. Participants were further invited for semi-structured exit interviews (n = 9). A set of Anovas was performed to test the main hypotheses while thematic analysis was performed to analyze the qualitative data. RESULTS Results showed a significant increase in hand hygiene over time across all conditions. There was no interaction effect of time and intervention condition. Likewise, no between-group difference in engagement, usability and satisfaction emerged. Seven themes (e.g., “variety and timeliness of the workload”, “social interaction”) were found in the thematic analysis. CONCLUSIONS The current findings evidenced no effect of intervention condition of a habit, motivation and social norms module on hand hygiene, engagement, usability and satisfaction. In the absence of quantitative differences, we relied on the results from the thematic analysis to select the best version of Soapp for the evaluation phase. CLINICALTRIAL NCT04830761 INTERNATIONAL REGISTERED REPORT RR2-10.1136/bmjopen-2021-055971