An assessment on the interplay of digital proximity app use and vaccine uptake for SARS-CoV-2 transmission mitigation in Switzerland

Abstract

Introduction Adherence to digital proximity tracing apps and preventive measures leading up to and following widespread SARS-CoV-2 vaccine rollout remains unclear. Our study aims to evaluate the relative effect of digital proximity tracing app use, SARS-CoV-2 vaccine uptake and adherence to additional preventive measures in a localized context of the pandemic. Methods We report findings from two population-based longitudinal cohorts in Switzerland, the Corona Immunitas Digital Follow-up eCohort (CI-DFU) and the COVID-19 Social Monitor (CSM) studies in 2021. Failure time analyses were conducted for each study cohort, stratified by age group. Cox proportional hazards regression models with time-varying covariates were used to estimate adjusted hazard ratios (aHR). The analyses assessed vaccine uptake and SwissCovid app uninstalling outcomes, with the outcomes interchanging as the exposures in two separate substudies. Results We observed a dichotomy of individuals who did not use the app during the study period and did not get vaccinated, and who used the SwissCovid app during the study period and got vaccinated during the study period. We found an increased uptake of the vaccine associated with SwissCovid app use (aHR, 1.51; 95% CI: 1.40–1.62 [CI-DFU]; aHR, 1.79; 95% CI: 1.62–1.99 [CSM]) or adherence to preventive measures (aHR, 1.44; 95% CI: 1.28–1.62 [CI-DFU]; aHR, 1.82; 95% CI: 1.52–2.18 [CSM]). Decreased SwissCovid uninstallation risk was observed for participants who received their first vaccine dose throughout the study period (aHR, 0.55; 95% CI: 0.38–0.81 [CI-DFU]; aHR, 0.45; 95% CI: 0.27–0.78 [CSM]). Conclusion In evolving pandemic contexts, these findings can assist public health authorities in designing evidence-based communication strategies to enable adoption of preventive measures and novel health technologies across all population groups.