Hospital-acquired coronavirus disease 2019 (COVID-19) among patients of two acute-care hospitals: Implications for surveillance

The coronavirus disease 2019 (COVID-19) pandemic has posed unprecedented challenges to infection control and public health professionals. These challenges have necessitated rapid development and implementation of interventions using reports from worldwide sentinel locations,¹ recognized best practices for control of respiratory virus transmission,^2,3 and professional websites.⁴ With sparse evidence and personal protective equipment shortages, infection control departments adopted a necessarily agile framework for rapid iterative decision making to control intrafacility transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Decision-making domains have included mask and respirator use, face shields, extended use and reuse of personal protective equipment, protections for aerosol-generating procedures, visitation policies, patient and healthcare personnel (HCP) screening, and patient and HCP cohorting protocols.

Before the COVID-19 surge in the Chicago region, early publications and anecdotal evidence documented a high reproductive rate for SARS-CoV-2, with potential to spread both among and between hospital patients and HCWs.^5,6 The efficiency of SARS-CoV-2 transmission exceeds that of pandemic influenza and MERS,⁷ underscoring the high risk of transmission in confined indoor spaces with close interpersonal contact,^8,9 such as hospitals. Fortunately, subsequent evidence from an acute-care institution indicated that stringent infection-control interventions can successfully minimize SARS-CoV-2 spread.¹⁰ However, infection clusters remain possible and likely are driven by patient and ecological factors (eg, opportunities for exposure to SARS-CoV-2).¹¹ To understand whether infection control policies and practices remain effective as COVID-19 evolves, we need standardized, reliable capture of hospital-acquired COVID-19 cases. It is appealing to leverage lessons learned from algorithmic determinations of other healthcare-associated events to COVID-19 and to rely solely on readily available data routinely captured in the electronic medical record such as laboratory-identified event reporting for Clostridium difficile.¹² However, detection of COVID-19 solely through electronically available data might be susceptible to misclassification.

We performed a retrospective observational study addressing 2 objectives. First, we evaluated the extent of hospital-acquired SARS-CoV-2 infection among inpatients by performing an electronic query for potential cases followed by chart review. Second, we assessed the possibility of automated detection of hospital-acquired SARS-CoV-2 using solely temporal criteria. We retrieved all SARS-CoV-2 test results and, relying on timing of specimen collection in electronic healthcare record (EHR) data, we identified cases of potential hospital acquisition. We performed chart review to...