Effect of social distancing on injury incidence during the COVID-19 pandemic: an interrupted time-series analysis.

Objectives: To evaluate the effects of social distancing on the incidence and characteristics of injuries during the COVID-19 pandemic.

Design And Setting: This cross-sectional study used the National Emergency Department Information System (NEDIS) database.

Participants: Injured patients who visited all 402 emergency departments (EDs) between 29 February and 29 May 2020 (after-distancing), and in the corresponding period in 2019 (before distancing) to control for seasonal influences.

Outcome Measures: The study outcome was the incidence of injury. Using the interrupted time-series analysis models, we analysed weekly trends of study outcomes in both periods (before and after distancing), the step change (the effect of intervention), and the slope change over two periods (the change in the effect over time).

Results: The incidence rates of injury per 100 000 person-days were 11.2 and 8.6 in the before-distancing and after-distancing periods, respectively. In the after-distancing period, the incidence rate of injury decreased (step change -3.23 (95% CI -4.34 to -2.12) per 100 000 person-days) compared with the before-distancing period, while the slope change was 0.10 (95% CI 0.04 to 0.24). The incidence rate ratios of all injuries and intentional injuries for the after-distancing period were 0.67 (95% CI 0.60 to 0.75) and 1.28 (95% CI 1.18 to 1.40), respectively, compared with the before-distancing period.

Conclusions: Fewer injuries occurred after the implementation of social distancing programme compared with the same period in the previous year. However, this effect gradually decreased postimplementation.