ABSTRACT
Background: SARS-CoV-2 is known to transmit in hospital settings, but the contribution of infections acquired in hospitals to the epidemic at a national scale is unknown. Methods: We used comprehensive national English datasets to determine the number of COVID-19 patients with identified hospital-acquired infections (with symptom onset >7 days after admission and before discharge) in acute English hospitals up to August 2020. As patients may leave the hospital prior to detection of infection or have rapid symptom onset, we combined measures of the length of stay and the incubation period distribution to estimate how many hospital-acquired infections may have been missed. We used simulations to estimate the total number (identified and unidentified) of symptomatic hospital-acquired infections, as well as infections due to onward community transmission from missed hospital-acquired infections, to 31 st July 2020. Results: In our dataset of hospitalised COVID-19 patients in acute English hospitals with a recorded symptom onset date (n = 65,028), 7% were classified as hospital-acquired. We estimated that only 30% (range across weeks and 200 simulations: 20-41%) of symptomatic hospital-acquired infections would be identified, with up to 15% (mean, 95% range over 200 simulations: 14.1%-15.8%) of cases currently classified as community-acquired COVID-19 potentially linked to hospital transmission. We estimated that 26,600 (25,900 to 27,700) individuals acquired a symptomatic SARS-CoV-2 infection in an acute Trust in England before 31st July 2020, resulting in 15,900 (15,200-16,400) or 20.1% (19.2%-20.7%) of all identified hospitalised COVID-19 cases. Conclusions: Transmission of SARS-CoV-2 to hospitalised patients likely caused approximately a fifth of identified cases of hospitalised COVID-19 in the “first wave” in England, but less than 1% of all infections in England. Using time to symptom onset from admission for inpatients as a detection method likely misses a substantial proportion (>60%) of hospital-acquired infections.
Subject(s)
COVID-19ABSTRACT
Hospital-based transmission played a dominant role in MERS-CoV and SARS-CoV epidemics but large-scale studies of its role in the SARS-CoV-2 pandemic are lacking. Such transmission risks spreading the virus to the most vulnerable individuals and can have wider-scale impacts through hospital-community interactions. Using data from acute hospitals in England we quantify within-hospital transmission, evaluate likely pathways of spread and factors associated with heightened transmission risk, and explore the wider dynamical consequences. We show that hospital transmission is likely to have been a major contributor to the burden of COVID-19 in England. We estimate that between June 2020 and March 2021 between 95,000 and 167,000 patients acquired SARS-CoV-2 in hospitals with nosocomially-infected patients likely to have been the main sources of transmission to other patients. Increased transmission to patients was associated with hospitals having fewer single rooms and lower heated volume per bed. Moreover, we show that reducing hospital transmission could substantially enhance the efficiency of punctuated lockdown measures in suppressing community transmission. These findings reveal the previously unrecognised scale of hospital transmission, have direct implications for targeting of hospital control measures, and highlight the need to design hospitals better-equipped to limit the transmission of future high consequence pathogens.
Subject(s)
COVID-19 , Cross InfectionABSTRACT
Nosocomial transmission of SARS-CoV-2 has the potential to place a large burden on the healthcare system through, for example, increased patient length of stay, pressure on specialist care capacity and staff shortages. In England, a number of interventions were applied in hospitals over wave 1 of the COVID-19 pandemic to limit the spread of SARS-CoV-2 among both hospital inpatients and healthcare workers (HCWs). Using a computational modelling approach, we have estimated the combined effect of these, and other changes within the hospital setting, to determine how many nosocomial infections were averted. While highly uncertain, due primarily to important gaps in the evidence base, model results suggest that in a scenario with high occupancy, no testing, reduced infection prevention and control (IPC) measures, increased visitors, and longer patient stays, approximately 5.2% (3.9-7.2%) of all susceptible inpatients (n=140,603; 95% CI, 89,352-197,977 patients in total), and 51.1% (43.6, 55.3%) of patient-facing HCWs could have been nosocomially infected with SARS-CoV-2 over wave 1 compared with the 1.0% (0.7, 1.2%) of patients (33,922; 24,089- 41,015) and 20.3% (15.8-29.4%) of HCW observed to be nosocomially infected. The most effective interventions for prevention of nosocomial infections in patients were decreasing occupancy, increasing spacing between beds, and testing patients on admission, resulting in a reduction of 23,434 (14,544, 31,341), 10,979 (2,458, 16,979), and 9,505, (4588, 12,823) infections, respectively. Although every intervention had some impact, it was the collective impact of all interventions that demonstrated greatest effect, averting 140,603 (89,352, 197,977) infections in inpatients. In HCWs, the most effective intervention was universal mask use, with inclusion of universal masking as part of IPC measures averting 46.0% (42.9-54.5%) of infections in HCWs resulting in 17,980 (2,772-28,450) fewer infections per 100,000 patient-facing HCWs. Interventions introduced over wave 1 of the SARS-CoV-2 pandemic in England reduced HCW infection rates by 51.1% (43.6-55.3%).
Subject(s)
COVID-19 , Cross InfectionABSTRACT
ObjectivesNosocomial transmission was an important aspect of SARS-CoV-1 and MERS-CoV outbreaks. Healthcare-associated SARS-CoV-2 infection has been reported in single and multi-site hospital-based studies in England, but not nationally. MethodsAdmission records for all hospitals in England were linked to SARS-CoV-2 national test data for the period 01/03/2020 to 31/08/2020. Case definitions were: community-onset community-acquired (CO.CA), first positive test (FPT) <14 days pre-admission, up to day 2 of admission; hospital-onset indeterminate healthcare-associated (HO.iHA), FPT on day 3-7; hospital-onset probable healthcare-associated (HO.pHA), FPT on day 8-14; hospital-onset definite healthcare-associated (HO.HA), FPT from day 15 of admission until discharge; community-onset possible healthcare-associated (CO.pHA), FPT [≤]14 days post-discharge. ResultsOne-third (34.4%, 100,859/293,204) of all laboratory-confirmed COVID-19 cases were linked to a hospital record. HO.pHA and HO.HA cases represented 5.3% (15,564/293,204) of all laboratory-confirmed cases and 15.4% (15,564/100,859) of laboratory-confirmed cases among hospital patients. CO.CA and CO.pHA cases represented 86.5% (253,582/293,204) and 5.1% (14,913/293,204) of all laboratory-confirmed cases, respectively. ConclusionsUp to 1 in 6 SARS-CoV-2 infections among hospitalised patients with COVID-19 in England during the first 6 months of the pandemic could be attributed to nosocomial transmission, but these represent less than 1% of the estimated 3 million COVID-19 cases in this period.