Association between positive preadmission screening and COVID-19 community transmission: A retrospective observational study during an emergent novel infectious disease pandemic.

Background: After COVID-19 emerged, hospitals adopted preadmission screening to detect asymptomatic cases and avert nosocomial outbreaks; whether such clinical screening should be routine policy remains debated and has not been quantified in Japan. Objective: To evaluate preadmission clinical screening as a component of pandemic preparedness. Methods: The primary outcome was positivity on preadmission screening. We modeled COVID-19 positivity among asymptomatic preadmission patients using regression and a Tobit specification to accommodate excess zeros, then developed a predictive model. Analyses used hospital data linked to prefecture-level indicators of community transmission, including newly confirmed cases and influenza-like-illness (ILI) sentinel activity. Results: In this single-center retrospective study, 5897 newly confirmed COVID-19 cases were analyzed at the hospital. During the same period, Mie Prefecture reported 355,879 cases overall, including 45,551 visits to ILI sentinel sites. In 2022, screening positivity among asymptomatic preadmission patients correlated strongly with the number of newly confirmed cases in the prefecture. The model predicted non-zero screening positivity when newly confirmed prefectural cases exceeded ∼10,000, regardless of assumed ILI positivity. When prefectural cases were <2,000, predicted screening positivity was ∼0 even if assumed ILI positivity was ∼40 %. Discussion and conclusions: Findings suggest conditions for conducting preadmission clinical screening during the COVID-19 pandemic, which can support healthcare infrastructure preparedness against pandemics of novel infectious diseases.