The burden of nosocomial covid-19: results from the Wales multi-centre retrospective observational study of 2518 hospitalised adults.

Ponsford, M. J.; Jefferies, R.; Davies, C.; Farewell, D.; Humphreys, I. R.; Jolles, S.; Fairbairn, S.; Lewis, K.; Menzies, D.; Benjamin, A.; Thaivalappil, F.; Barry, S. M.

Objectives: To define the burden of nosocomial (hospital-acquired) novel pandemic coronavirus (covid-19) infection among adults hospitalised across Wales. Design: Retrospective observational study of adult patients with polymerase chain reaction (PCR) confirmed SARS-CoV-2 infection between 1st March to 1st July 2020 with a recorded hospital admission within the subsequent 31 days. Outcomes were collected up to 20th November using a standardised online data collection tool. Setting: Service evaluation performed across 18 secondary or tertiary care hospitals. Participants: 4112 admissions with a positive SARS-CoV-2 PCR result between 1st March to 1st July 2020 were screened. Anonymised data from 2518 participants were returned, representing over 60% of adults hospitalised across the nation of Wales. Main outcome measures: The prevalence and outcomes (death, discharge) for nosocomial covid19, assessed across of a range of possible case definitions. Results: Inpatient mortality rates for nosocomial covid19 ranged from 38% to 42% and remained consistently higher than participants with community acquired infection (31% to 35%) across a range of case definitions. Participants with nosocomial-acquired infection were an older, frailer, and multi-morbid population than those with community-acquired infection. Based on the Public Health Wales case definition, 50% of participants had been admitted for 30 days prior to diagnostic testing. Conclusions: This represents the largest assessment of clinical outcomes for patients with nosocomial covid-19 in the UK to date. These findings suggest that inpatient mortality rates from nosocomial-infection are likely higher than previously reported, emphasizing the importance of infection control measures, and supports prioritisation of vaccination for covid-19 negative admissions and trials of post-exposure prophylaxis in inpatient cohorts. Trial registration: This project was approved and sponsored by the Welsh Government, as part of a national audit and quality improvement scheme for patients hospitalised covid-19 across Wales.