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.

Fig. 1.

Flowchart for categorization of SARS-CoV-2–positive specimens acquired during an acute-care hospital stay at 2 hospitals in Chicago, Illinois. Note. SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; CA, community acquired; OSH, other hospital; Sx, signs or symptoms; Dx, diagnosis; HA, hospital acquired. ^aFrom Table 1, 4 patients were excluded as false positives because SARS-CoV-2 was detected by a point-of-care test, and all 4 had at least a subsequent negative RT-PCR assay and no COVID-19 symptoms. ^bEvaluated for COVID-19 symptoms or signs and chest radiographs within 1 day before or after specimen collection date for initial SARS-CoV-2 positive result, as follows: (1) new or worsening hypoxia and new symptoms or (2) new or progressive radiographically identified pulmonary infiltrates and new symptoms. ^cAlternate Dx, a diagnosis deemed as likely or more likely than COVID-19.