key: cord-0992044-4qfdrr5j
authors: Ladhani, Shamez N; Chow, J. Yimmy; Janarthanan, Roshni; Fok, Jonathan; Crawley-Boevey, Emma; Vusirikala, Amoolya; Fernandez, Elena; Perez, Marina Sanchez; Tang, Suzanne; Dun-Campbell, Kate; Evans, Edward Wynne-; Bell, Anita; Patel, Bharat; Amin-Chowdhury, Zahin; Aiano, Felicity; Paranthaman, Karthik; Ma, Thomas; Saavedra-Campos, Maria; Myers, Richard; Ellis, Joanna; Lackenby, Angie; Gopal, Robin; Patel, Monika; Chand, Meera; Brown, Kevin; Hopkins, Susan; Shetty, Nandini; Zambon, Maria; Ramsay, Mary E
title: INCREASED RISK OF SARS-CoV-2 INFECTION IN STAFF WORKING ACROSS DIFFERENT CARE HOMES ENCHANCED CoVID-19 OUTBREAK INVESTIGATIONS IN LONDON CARE HOMES
date: 2020-07-29
journal: J Infect
DOI: 10.1016/j.jinf.2020.07.027
sha: 12018d0f41e057f989b4985f54460c7772549a3a
doc_id: 992044
cord_uid: 4qfdrr5j

BACKGROUND: Care homes have been disproportionately affected by the COVID-19 pandemic and continue to suffer large outbreaks even when community infection rates are declining, thus representing important pockets of transmission. We assessed occupational risk factors for SARS-CoV-2 infection among staff in six care homes experiencing a COVID-19 outbreak during the peak of the pandemic in London, England. METHODS: Care home staff were tested for SARS-COV-2 infection by RT-PCR and asked to report any symptoms, their contact with residents and if they worked in different care homes. Whole genome sequencing (WGS) was performed on RT-PCR positive samples. RESULTS: In total, 51 (20%) of 250 staff were SARS-CoV-2 positive but only 11/51 (22%) were symptomatic. Among staff working in a single care home, SARS-CoV-2 positivity was 15% (2/13), 16% (7/45) and 17% (28/165) in those reporting no, occasional and regular contact with residents. In contrast, staff working across different care homes (14/27, 52%) had a 4.2-fold (95% CI, 2.1-8.4; P<0.001) higher risk of SARS-CoV-2 positivity than staff working in single care homes (37/223, 17%). WGS identified SARS-CoV-2 clusters involving staff only, including some that included staff working across different care homes. CONCLUSIONS: SARS-CoV-2 positivity was significantly higher among staff working across different care homes than those who were working in the same care home. We found local clusters of SARS-CoV-2 infection between staff only, including those with minimal resident contact. Infection control should be extended for all contact, including those between staff, whilst on care home premises.

Fok, FFPH, 3 Emma Crawley-Boevey, MFPH, 3 Amoolya Vusirikala, MPH, 3 Elena Fernandez, BSc., 3 Marina Sanchez Perez, MPH, 3 Suzanne Tang, MPH, 3 Kate Dun-Campbell, MRCGP, 3 Edward Wynne-Evans, FFPH, 3 Anita Bell, FFPH, 3 Bharat Patel, FRCPath, 3 Zahin Amin-Chowdhury, BSc, 1 Myers, PhD, 5 Joanna Ellis, PhD, 6 Angie Lackenby, PhD, 6 Robin Gopal, PhD, 6 Monika Patel, BSc, 6 Meera Chand, FRCPath, 7 Kevin Brown, FRCPath, 6 Susan Hopkins, 7 CoG Consortium, 8 Nandini Shetty, FRCPath, 6 Maria Zambon, FRCPath, 6 Health England during April 10-13, 2020 were investigated. These were mainly nursing or mixed nursing/residential homes of different sizes, providing care for 43-100 residents with 20-130 staff. All staff and residents provided a nasal self-swab which was tested for SARS-CoV-2 by real-time reverse transcription (RT) PCR assay on an Applied Biosystems 7500 FAST system targeting a conserved

region of the open reading frame (ORF1ab) gene of SARS-CoV-2, together with an internal control. 6 Whole genome sequencing (WGS) was performed on all RT-PCR positive samples. 7 Staff were asked to report any symptoms, their contact with residents and if they worked in different care homes. In a recent review of evidence to stop pandemics spreading across care homes, the Centre for Evidence Based Medicine identified 30 studies on viral infection control, relating mainly to influenza, in care homes. 9 In addition to hand washing, environmental decontamination, restricted visitation and rapid testing, the review recommended allocating staff to one facility consistently may reduce spread across several locations but the evidence supporting this recommendation was indirect and limited. Care home staff are known to have multiple jobs, including working across different care homes and other healthcare facilities. In a recent US survey, 17% of care home staff had a second job and more than 60% held double-or triple-duty care giving roles. 10 Additionally, in many countries including the UK and the US, care homes are heavily reliant on temporary "bank" or agency staff to provide cover for their staff in case of shortages or sick leave. 11, 12 Staff are also recognised sources of infection, especially respiratory and gastrointestinal viruses, in care homes, 13 and COVID-19 is no exception. 14, 15 In a recent care home outbreak in King County, Washington State, US, a health care provider was identified as the index case who might have contributed to rapid spread in one of the facilities. 14 Similarly, in Ontario, the strongest predictor of death in residents was SARS-CoV-2 infection in a staff member in the previous week. 15 Modelling simulations have found that staff are a key source of outbreaks and transmission; in particular, the modelling identified staff re-entry into care homes as the critical pathway for contagion. 11 That model suggested that limiting the potential for staff exposure to the virus in the community, through virtually complete facility isolation or at least 10 days in continuous residence at the facility for example, significantly reduced the risk of introduction into the care home, although these measures were considered socially unworkable. 11 6

Working across different care homes, therefore, could potentially increase the risk of introducing SARS-CoV-2 into the care home. Given the high rates of asymptomatic infection with SARS-CoV-2, the virus could spread rapidly among residents and staff before symptoms appear and an outbreak is declared. 3 We found significantly higher SARS-CoV-2 infection rates among staff who worked in different care homes and this risk increased with the frequency of working across care homes, where nearly 60% tested positive for SARS-CoV-2. Given that stringent infection control practices, including closure to visitors, were reported to be in place by the time of testing, staff working across care homes (most of whom asymptomatic at the time of testing) were, therefore, a significant potential source and reservoir of SARS-CoV-2. Reassuringly, this cohort accounted for only 12% of the tested workforce.

Within individual care homes, we also identified similar SARS-CoV-2 infection rates among staff with different exposures to the residents, including those who reported no contact with residents. This is consistent with provisional data from a recent national survey in England which reported no difference in SARS-CoV-2 positivity between patient-facing healthcare workers, resident-facing social care staff and those not working in these roles. 16 Finally, we identified a proportion of SARS-CoV-2 positive staff members, especially among those working across different care homes, who were symptomatic at the time of testing (Figure 1) . A recent study reported that more than 70% of care home staff felt obligated to come to work even when they were sick. 10 This problem of presenteeism has the potential to jeopardise the health of the residents, other staff, visitors and household members. In addition to implementing stringent infection control practices, facilities could help mitigate this risk by increasing wage, providing incentives for working in single care homes, and offering sick leave and benefits especially for the lowest wage workers, as has been recommended by others. [10] [11] [12] 

The strength of this surveillance is the large numbers of residents and staff tested at the same time across six London care homes during the peak of the COVID-19 pandemic. We were already reported the high rates of asymptomatic infection in residents and staff at the time of testing and the high case fatality rates (35%) among symptomatic SARS-CoV-2 positive residents compared to asymptomatic SARS-CoV-2 positive as well as the SARS-CoV-2 negative residents in the same care homes. A limitation of this analysis was that, although we achieved a 100% response rate, some staff may not have wished for their employers to know if they work in different care homes. This, however, would only serve to widen the difference in SARS-CoV-2 positivity rates between staff working in single care homes compared to those working across different care homes. We were also unable to identify the source of infection among the staff, which could have been acquired from the community, from the residents or from other staff working in the care homes.

We identified very high rates of SARS-Cov-2 infection in staff working across different care homes compared to those who were working in the same care home. Staff should be encouraged and incentivised to work in single care homes and movement of staff across multiple care homes should be limited. Where necessary, temporary care home staff need to be fully inducted into any new working environment, including infection prevention control measures and regular testing for SARS-CoV-2 should be considered. We also found local clusters of SARS-CoV-2 infection between staff only in some care homes. Infection prevention and control measures should not be restricted to contact with residents but needs to be extended for all contact, including those between staff, whilst on care home premises.

Ethics approval: this investigation was conducted as part of Public Health England's responsibility to investigate infectious disease outbreaks during the COVID-19 pandemic

Funding: This study was internally funded by Public Health England. 

Presymptomatic SARS-CoV-2 Infections and Transmission in a Skilled Nursing Facility

Epidemiology of Covid-19 in a Long-Term Care Facility in King County

SARS-CoV-2 infection, clinical features and outcome of COVID-19 in United Kingdom nursing homes

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The Centre for Evidence-based Medicine: How can pandemic spreads be contained in care homes

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