Transmission of community- and hospital-acquired SARS-CoV-2 in hospital settings in the UK: A cohort study

• DOI: 10.1371/journal.pmed.1003816
• Publication Date: 2021-10-13T00:26:22Z
• Authors: Yin Mo; David W. Eyre; Sheila F. Lumley; Timothy M. Walker; Robert H. Shaw; Denise O’Donnell; Lisa Butcher; Katie Jeffery; Christl A. Donnelly; ; Ben S. Cooper
• Keywords: Male; Nurses; Logistic regression; Infection control; Social Distancing; Pediatrics; Infectious Disease Transmission, Professional-to-Patient; Cohort Studies; Engineering; 0302 clinical medicine; Risk Factors; Psychological intervention; Observational study; Internal medicine; 11 Medical and Health Sciences; Aged, 80 and over; Psychiatry; Cross Infection; Airborne Transmission of Respiratory Viruses; Modeling the Dynamics of COVID-19 Pandemic; R; Cohort; Middle Aged; Hospitals; 3. Good health; Community-Acquired Infections; Hospitalization; Serology; Oncology; Modeling and Simulation; Physical Sciences; Impact of COVID-19 on Cancer Patients and Care; Medicine; Emergency medicine; Female; Cohort study; Research Article; Adult; Pulmonary and Respiratory Medicine; 570; Infectious Disease Transmission, Patient-to-Professional; Health Personnel; Immunology; 610; 03 medical and health sciences; Oxford COVID infection review team; General & Internal Medicine; 616; Health Sciences; FOS: Mathematics; Humans; Intensive care medicine; Antibody; Aged; Infection Control; SARS-CoV-2; FOS: Clinical medicine; COVID-19; Transmission (telecommunications); Electrical engineering; Mathematics

Background Nosocomial spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been widely reported, but the transmission pathways among patients and healthcare workers (HCWs) are unclear. Identifying the risk factors and drivers for these nosocomial transmissions is critical for infection prevention and control interventions. The main aim of our study was to quantify the relative importance of different transmission pathways of SARS-CoV-2 in the hospital setting.

Methods and findings This is an observational cohort study using data from 4 teaching hospitals in Oxfordshire, United Kingdom, from January to October 2020. Associations between infectious SARS-CoV-2 individuals and infection risk were quantified using logistic, generalised additive and linear mixed models. Cases were classified as community- or hospital-acquired using likely incubation periods of 3 to 7 days. Of 66,184 patients who were hospitalised during the study period, 920 had a positive SARS-CoV-2 PCR test within the same period (1.4%). The mean age was 67.9 (±20.7) years, 49.2% were females, and 68.5% were from the white ethnic group. Out of these, 571 patients had their first positive PCR tests while hospitalised (62.1%), and 97 of these occurred at least 7 days after admission (10.5%). Among the 5,596 HCWs, 615 (11.0%) tested positive during the study period using PCR or serological tests. The mean age was 39.5 (±11.1) years, 78.9% were females, and 49.8% were nurses. For susceptible patients, 1 day in the same ward with another patient with hospital-acquired SARS-CoV-2 was associated with an additional 7.5 infections per 1,000 susceptible patients (95% credible interval (CrI) 5.5 to 9.5/1,000 susceptible patients/day) per day. Exposure to an infectious patient with community-acquired Coronavirus Disease 2019 (COVID-19) or to an infectious HCW was associated with substantially lower infection risks (2.0/1,000 susceptible patients/day, 95% CrI 1.6 to 2.2). As for HCW infections, exposure to an infectious patient with hospital-acquired SARS-CoV-2 or to an infectious HCW were both associated with an additional 0.8 infection per 1,000 susceptible HCWs per day (95% CrI 0.3 to 1.6 and 0.6 to 1.0, respectively). Exposure to an infectious patient with community-acquired SARS-CoV-2 was associated with less than half this risk (0.2/1,000 susceptible HCWs/day, 95% CrI 0.2 to 0.2). These assumptions were tested in sensitivity analysis, which showed broadly similar results. The main limitations were that the symptom onset dates and HCW absence days were not available.

Conclusions In this study, we observed that exposure to patients with hospital-acquired SARS-CoV-2 is associated with a substantial infection risk to both HCWs and other hospitalised patients. Infection control measures to limit nosocomial transmission must be optimised to protect both staff and patients from SARS-CoV-2 infection.