Incidence and outcomes of hospital-associated coronavirus disease 2019 (COVID-19) before and after emergence of the severe acute respiratory coronavirus virus 2 (SARS-CoV-2) omicron variant

Secondary outcomes were 30-day case fatality rate (CFR) of HA–COVID-19 including only deaths attributable to SARS-CoV-2 infection per the death certificate, admission to an intensive care unit (ICU) for severe COVID-19, and acute-care length of stay from date of detection. Incidence, Characteristics, and Outcomes of Hospitalized Patients With Healthcare-Associated COVID-19 During the Pre-omicron and Post-omicron Periods Characteristic Pre-omicron Perioda Post-omicron Periodb Total patient days 187,096 191,172 Non–COVID-19 patient daysc 181,638 183,007 Hospital admissions 27,648 27,079 Total COVID-19 cases detected, no. 705 1161 Daily COVID-19 case patient census, median (IQR) 5 (2–26) 18 (12–27) COVID-19 cases from community, no. (%) 671 (95.2) 850 (73.2) HA–COVID-19 cases, no. (%) 34(4.8) 311(26.8) Incidence per 1,000 non-COVID-19 patient days 0.19 1.70 Age, median y (IQR) 74.0 (56.5–85.3) 74.0 (62.0–84.0) Sex, male, no. (%) 22 (64.7) 160 (51.4) Minimum of 2 doses of COVID-19 vaccine (%) 1(2.9) 279 (89.7) Attributable service, no. (%) Medicine 15 (44.1) 150 (48.2) Oncology 3 (8.8) 53 (17.0) Surgery 12 (35.3) 78 (25.1) ICU 1 (2.9) 8 (2.6) Psychiatry 3 (8.8) 22 (7.1) Days from admission to detection, median (IQR) 11 (9.0–18.0) 11 (7.0–19.0) Identified outside acute care, no. (%) 5 (14.7) 44 (14.1) Outbreak associated, no. (%) 8 (23.5) 177 (56.9) Identified following roommate exposure, no. (%) 9 (26.5) 69 (22.2) Treatment for COVID-19, no. (%)d 10 (29.4) 112 (36.0) Outcomes of patients with HA–COVID-19 Length of stay, median d (IQR) 11 (5.0–23.5) 11 (4.0–18.0) Admitted to ICU, no. (%) 3 (8.8) 11 (3.5) Case fatality, no. (%) 5 (14.7) 8 (2.6) Note. [...]because patients testing negative for SARS-CoV-2 on admission were not routinely retested within 72 hours, patients incubating virus on admission may have been missed and counted as HA–COVID-19 cases if subsequently detected, although a similar testing strategy was in place during both the pre- and post-omicron periods. [...]although changes in the visitation policy during the post-omicron period were associated with an increase in HA–COVID-19, this does not account for the overall 9-fold increase in risk that we observed.