Hospital onset SARS-CoV-2 infections in the Omicron wave: patterns of infection in the context of asymptomatic testing.

During the course of the COVID-19 pandemic, nosocomial SARS-CoV-2 infections have been detected in approximately 0.5% of inpatients [ [1] Stimson J. Pouwels K.B. Hope R. Cooper B.S. Presanis A.M. Robotham J.V. Estimation of the impact of hospital-onset SARS-CoV-2 infections on length of stay in English hospitals using causal inference. BMC Infect Dis. 2022; 22: 1-2 Crossref PubMed Scopus (1) Google Scholar ] in English hospitals, with increased length of stay (LOS) a key determinant of nosocomial infection risk [ [2] Cooper B, Evans S, Jafari Y, Pham TM, Lim C, Pritchard M, et al. Research square [preprint]. The burden and dynamics of hospital-acquired SARS-CoV-2 in England. https://doi.org/10.21203/rs.3.rs-1098214/v1. Google Scholar ]. Routine testing and subsequent cohorting of patients was a key strategy to prevent nosocomial transmission, with all patients tested on admission, and asymptomatic patients that remained in hospital retested on days 3 and 5–7 post admission [ [3] NHS England Living with COVID-19 – testing update. https://www.england.nhs.uk/coronavirus/documents/living-with-covid-19-testing-update/#patientDate: 2022 Google Scholar ]. Inpatients were also tested following the development of COVID-19 symptoms. Patients undergoing elective surgery were asked to test at home three days before their appointment with a negative test result required before surgery would be performed [ [4] UK Health Security AgencyTesting for COVID-19 before a hospital procedure. https://www.gov.uk/government/publications/testing-for-coronavirus-before-hospital/testing-for-covid-19-before-a-hospital-procedureDate: 2022 Google Scholar ].