Structural and organizational determinants of the capacity for COVID-19 testing and diagnoses in children: Insights from the 2009 influenza and COVID-19 pandemics

Background: This study explored factors associated with testing and diagnoses for children with COVID-19 at the hospital level and investigated whether the capacity of testing and diagnoses during the 2009 influenza pandemic was associated with that during COVID-19 pandemic. Methods: In this observational study, we analyzed data obtained from the Japan Medical Data Center database, comprising 4906 medical facilities and 1.7 million infectious disease-related visits among children aged <20 years in 2020-2021. Multivariable generalized linear models were used to explore determinants of testing and diagnoses capacity for COVID-19 and investigate the association between the capacity during the 2009 influenza and COVID-19 pandemics. Results: Public hospitals (adjusted incidence rate ratio [aIRR], 1.52; 95%CI, 1.26-1.82) and university hospitals (aIRR, 1.44; 95%CI, 1.14-1.80) were more likely to perform testing for COVID-19 among children, compared to clinics. The highest testing rate was observed in the department of internal medicine (aIRR, 1.64; 95%CI, 1.32-2.04), followed by pediatrics (aIRR, 1.40; 95%CI, 1.10-1.78) and otolaryngology (aIRR, 1.21; 95%CI, 0.89-1.64). Cubic spline models demonstrated the dose-response relationships between testing rate for influenza in 2009 and testing rates for COVID-19. Compared to the medical facilities in the lowest quartile of testing rate for influenza in 2009, those in the highest quartile were more likely to perform testing for COVID-19 (aIRR, 1.62; 95%CI, 1.43-1.83). Conclusions: Our study provides insights into the capacity of testing and diagnoses for children, highlighting the dose-response relationship between the 2009 influenza and COVID-19 pandemics, which could be valuable in preparing healthcare systems for future pandemics.