Background: Various studies have demonstrated the usefulness of Google search data for public health-monitoring systems. The aim of this study is to be estimated interest of public in infectious diseases in infectious diseases in South Korea, the five other countries. Methods: We conducted cross-country comparisons for queries related to the H1N1 virus and Middle East respiratory syndrome coronavirus (MERS-CoV). We analyzed queries related to the novel coronavirus disease (COVID-19) from 20 January to 13 April 2020, and performed time-descriptive and correlation analyses on trend patterns. Results: Trends in H1N1, MERS-CoV, and COVID-19 queries in South Korea matched those in the five other countries and worldwide. The relative search volume (RSV) for the MERS-CoV virus increased as the cumulative number of confirmed cases in South Korea increased and decreased significantly as the number of confirmed cases decreased. The volume of COVID-19 queries dramatically increased as South Korea’s confirmed COVID-19 cases grew significantly at the community level. However, RSV remained stable over time. Conclusions: Google Trends provides real-time data based on search patterns related to infectious diseases, allowing for continuous monitoring of public reactions, disease spread, and changes in perceptions or concerns. We can use this information to adjust their strategies of the prevention of epidemics or provide timely updates to the public.

South Korea has experienced rapid economic development since the 1960s. However, pronounced regional disparities have concurrently emerged. Amid the escalating regional inequalities and persistent demographic challenges characterized by low fertility rates, regional decline has become a pressing issue. Therefore, the feasibility of expanding transportation networks as a countermeasure to regional decline has been proposed. This study utilizes the synthetic control method and spatial difference-in-differences methodologies to assess the impact of the 2017 opening of Seoul–Yangyang Expressway on economic development and population inflow within Hongcheon-gun, Inje-gun, and Yangyang-gun. The purpose of this study is to evaluate the effectiveness of highway development as a policy instrument to mitigate regional decline. Findings from the synthetic control method analysis suggest a positive impact of the opening of the expressway on Hongcheon-gun’s Gross Regional Domestic Product (GRDP) in 2018, as well as Yangyang-gun’s net migration rates from 2017 to 2019. Conversely, the spatial difference-in-differences analysis, designed to identify spillover effects, reveals negative impacts of the highway on the GRDP and net migration rates of adjacent regions. Consequently, although targeted transportation infrastructure development in key non Seoul Metropolitan cities may contribute to ameliorating regional imbalances, results indicate that such measures alone are unlikely to suffice in attracting population to small- and medium-sized cities outside the Seoul Metropolitan Area.