ABSTRACT
Background: The number of children with common pediatric infectious diseases (PIDs) other than coronavirus disease-2019 (COVID-19) decreased in 2020 compared with those in previous years worldwide. The present study tested the hypothesis that human mobility may be a potential factor contributing to reductions in PIDs that can be transmitted by droplets among children.Methods: An ecological study was conducted using two publicly available datasets: surveillance on infectious diseases collected by the Japanese government and COVID-19 community mobility reports presented by Google. Among common PIDs, we focused on focused on respiratory syncytial virus (RSV) infection, pharyngoconjunctival fever (PCF), group A streptococcal (GAS) pharyngitis, hand-foot-and-mouth disease (HFMD), and herpangina because of their nature as droplet-transmissible PIDs. The COVID-19 community mobility reports demonstrated percent decreases in the movement of people over time in groceries and pharmacies, parks, and transit stations. We compared the weekly trends in numbers of patients with PIDs identified in 2020 with those identified in the previous years 2015–2019. We then determined the associations between numbers of patients with PIDs and percentage decreases in human mobility during 2020 using Pearson correlation analysis.Results: Despite experiencing their peak seasons, dramatic reductions were observed in the numbers of patients with PCF and GAS pharyngitis after the 10th week in 2020. Beyond the 20th week, no seasonal peaks were observed in the numbers of patients with all PIDs identified in 2020. Significant correlations were found between percentage decreases in human mobility in transit stations and numbers of patients with HFMD (Pearson correlation coefficient [95% confidence interval]: 0.65 [0.44–0.79]), PCF (0.47 [0.21–0.67]), RSV infection (0.45 [0.19–0.66]), and GAS pharyngitis (0.34 [0.06–0.58]). No significant correlations were found between numbers of patients with PIDs and human mobility in parks.Conclusions: The highest correlations were found for the associations between numbers of patients with PIDs and human mobility in transit stations, suggesting that adult-to-child transmission may be a primary factor associated with increased numbers of patients with PIDs, rather than cross-transmission among children. A reduction in human mobility for adults may contribute toward decreases in the numbers of children with droplet-transmissible PIDs.