At least 11.1% of COVID-19 patients in 314 UK hospitals were infected after admission during the first wave of the pandemic, rising to between 16% and 20% in mid-May 2020.
The number of COVID-19 patients in UK hospitals reached high levels during the first pandemic wave of 2020, and higher levels still in the subsequent winter wave. A collaboration between various UK universities assessed the magnitude of nosocomial COVID-19 in acute and long-term National Health Service (NHS) hospital facilities in the UK during the first pandemic wave.
The research into hospital-acquired infections (HAIs) was led by Dr Jonathan Read from Lancaster University with colleagues from other institutions, including the Universities of Liverpool, Edinburgh, Birmingham and Imperial College London, and published in The Lancet.
The researchers examined records of COVID-19 patients in UK hospitals enrolled in the International Severe Acute Respiratory and emerging Infections Consortium (ISARIC) Clinical Characterisation Protocol UK (CCP-UK) study, who became ill before 1 August 2020.
They found that at least 11.1% of COVID-19 patients in 314 UK hospitals were infected after admission. The proportion of COVID-19 patients infected in hospital also rose to between 16% and 20% in mid-May 2020, long after the peak of admissions in the first wave.
The researchers said: "We estimate between 5,699 and 11,862 patients admitted in the first wave were infected during their stay in hospital. This is, unfortunately, likely to be an underestimate, as we did not include patients who may have been infected but discharged before they could be diagnosed."
Dr Jonathan Read, lead author at Lancaster University, said "Controlling viruses like SARS-CoV-2 (the virus that causes COVID-19) has been difficult in the past, so the situation could have been much worse. However, infection control should remain a priority in hospitals and care facilities."
Dr Chris Green, University of Birmingham, said: "There are likely to be a number of reasons why many patients were infected in these care settings. These include the large numbers of patients admitted to hospitals with limited facilities for case isolation, limited access to rapid and reliable diagnostic testing in the early stages of the outbreak, the challenges around access to and best use of PPE, our understanding of when patients are most infectious in their illness, some misclassification of cases due to presentation with atypical symptoms, and an under- appreciation of the role of airborne transmission."
There were marked differences in the numbers of patients infected in hospital according to the type of care provided. Hospitals providing acute and general care had lower proportions of hospital acquired infections (9.7%) than residential community care hospitals (61.9%) and mental health hospitals (67.5%), which reflects the outbreaks seen in care- homes.
Professor Calum Semple, University of Liverpool, said: "The reasons for the variation between settings that provide the same type of care requires urgent investigation to identify and promote best infection control practice. Research has now been commission to find out what was done well and what lessons need to be learned to improve patient safety."
Dr Anne Marie Docherty, University of Edinburgh, said: "The underlying reasons for these high rates of transmission in hospitals at the peak of the first wave must be investigated, so that we can improve safety and outcomes for our patients. Rates are considerably lower a year on, and people should not be deterred from attending hospital if they are unwell."
Full study
Hospital-acquired SARS-CoV-2 infection in the UK's first COVID-19 pandemic wave
Jonathan M Read, Chris A Green, Ewen M Harrison, Annemarie B Docherty, Sebastian Funk, Janet Harrison, Michelle Girvan, Hayley E Hardwick, Lance Turtle, Jake Dunning, Jonathan S Nguyen-Van-Tam, Peter JM Openshaw, J Kenneth Baillie, Malcolm G Semple, and theISARIC4C investigators
Published in The Lancet 12 August 2021
Prevention of hospital-acquired infections is a critical aspect of clinical management of COVID-19 as hospital-acquired infections have been a common feature of previous novel coronavirus outbreaks.
The number of COVID-19 patients in UK hospitals reached high levels during the first pandemic wave of 2020, and higher levels still in the subsequent winter wave. We assessed the magnitude of nosocomial COVID-19 in acute and long-term National Health Service (NHS) hospital facilities in the UK during the first pandmic wave.
We examined records of COVID-19 patients in UK hospitals enrolled in the International Severe Acute Respiratory and emerging Infections Consortium (ISARIC) WHO Clinical Characterisation Protocol UK (CCP-UK) study, with symptom onset before Aug 1, 2020.
We identified patients as having hospital-acquired infections using a combination of their admission date and symptom onset date, and estimates of their infection date based on the known incubation period distribution of SARS-CoV-2.
To incorporate uncertainty in individual patient's incubation periods, we imputed infection dates for patients and identified those admitted before infection as having hospital-acquired infections. Multiple imputation was used to generate estimates and CIs (appendix). We estimate that 11·3% (95% CI 11·1–11·6) of patients with COVID-19 in 314 UK hospitals became infected after hospital admission.
This proportion increased to at least 15·8% (17·6%; 15·8–19·6) of patients with COVID-19 by the middle of May, 2020, long after the peak of admissions. Using an extremely conservative threshold of symptom onset at least 14 days after admission to identify hospital-acquired infections, we estimate that 6·8% (95% CI 6·7–7·0) of all patients with COVID-19 had nosocomial infections, with a peak of 8·2% (7·0–9·6) of patients having nosocomial infections in mid-May.
There was marked heterogeneity in hospital-acquired infection proportion between hospital trusts and by the nature of care they provide (figure). Hospitals providing acute and general care had lower hospital-acquired infection proportions (9·7%; 95% CI 9·4–9·9) than residential community care hospitals (61·9%; 56·4–68·0) and mental health hospitals (67·5%; 60·1–75·8), reflecting outbreaks seen in care homes. The reasons for the variation between hospitals providing the same type of care require urgent investigation to identify and promote best infection control practice for future treatment of COVID-19 patients.
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