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



8th February 2021

Contributing to research themes:

This research has not been peer-reviewed, and has been posted on pre-print repository medRxiv. This is a preliminary report that should not be regarded as conclusive, guide clinical practice/health-related behaviour, or be reported in news media as established information.


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 – 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 covid-19, assessed across of a range of possible case definitions.

Results: Inpatient mortality rates for nosocomial covid-19 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.


Author list:

Mark J Ponsford, Rhys Jefferies, Chris Davies, Daniel Farewell, Ian R. Humphreys, Stephen Jolles, Sara Fairbairn, Keir Lewis, Daniel Menzies, Amit Benjamin, Favas Thaivalappil, Simon Barry