Association between traffic inflow and COVID-19 prevalence at the provincial level in South Korea

•The traffic volume from other areas in 2020 decreased by 3.7% compared with 2019.•In the second wave, COVID-19 cases increased as traffic inflow volume increased.•Traffic inflow volume and COVID-19 cases were positively correlated in 2 regions. To analyze the relationship between traffic inflow and COVID-19 prevalence in South Korea for formulating prevention policies for novel infections. We evaluated traffic inflow and new COVID-19 cases in 8 regions of Korea from January 1, 2020, to January 31, 2021. The toll collection system (TCS) traffic volume for 2019–2020 and traffic inflow trends were analyzed using independent samples t-test and nonlinear regression, respectively. The association between TCS traffic volume and new COVID-19 cases by city was analyzed using correlation analysis. Traffic inflow volume in 2020 decreased 3.7% from 2019. The TCS traffic inflow trend in the 8 provinces decreased during the first COVID-19 wave, gradually increased until the second wave, decreased after the second wave, and showed a sharp decrease in the third wave. There was a positive correlation between the traffic inflow volume and new cases in Busan-Gyeongnam and Jeonbuk, but not in Daegu-Gyeongbuk or Gangwon. A decrease in new COVID-19 cases in the regions was associated with increased traffic inflow volume. Therefore, the Korean government can establish preventive social distancing policies by identifying increases or decreases in traffic volume. These policies will also need to consider the distribution of vaccines in each area.