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

Abstract

Objectives: We quantified hospital-acquired coronavirus disease 2019 (COVID-19) during the early phases of the pandemic, and we evaluated solely temporal determinations of hospital acquisition. Design: Retrospective observational study during early phases of the COVID-19 pandemic, March 1-November 30, 2020. We identified laboratory-detected severe acute respiratory coronavirus virus 2 (SARS-CoV-2) from 30 days before admission through discharge. All cases detected after hospital day 5 were categorized by chart review as community or unlikely hospital-acquired cases, or possible or probable hospital-acquired cases. Setting: The study was conducted in 2 acute-care hospitals in Chicago, Illinois. Patients: The study included all hospitalized patients including an inpatient rehabilitation unit. Interventions: Each hospital implemented infection-control precautions soon after identifying COVID-19 cases, including patient and staff cohort protocols, universal masking, and restricted visitation policies. Results: Among 2,667 patients with SARS-CoV-2, detection before hospital day 6 was most common (n = 2,612; 98%); detection during hospital days 6-14 was uncommon (n = 43; 1.6%); and detection after hospital day 14 was rare (n = 16; 0.6%). By chart review, most cases after day 5 were categorized as community acquired, usually because SARS-CoV-2 had been detected at a prior healthcare facility (68% of cases on days 6-14 and 53% of cases after day 14). The incidence rates of possible and probable hospital-acquired cases per 10,000 patient days were similar for ICU- and non-ICU patients at hospital A (1.2 vs 1.3 difference, 0.1; 95% CI, -2.8 to 3.0) and hospital B (2.8 vs 1.2 difference, 1.6; 95% CI, -0.1 to 4.0). Conclusions: Most patients were protected by early and sustained application of infection-control precautions modified to reduce SARS-CoV-2 transmission. Using solely temporal criteria to discriminate hospital versus community acquisition would have misclassified many late onset SARS-CoV-2-positive cases.