Increased risk of SARS-CoV-2 infection in staff working across different care homes: enhanced CoVID-19 outbreak investigations in London care Homes

Abstract

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, 53 (21%) of 254 staff were SARS-CoV-2 positive but only 12/53 (23%) were symptomatic. Among staff working in a single care home, SARS-CoV-2 positivity was 15% (2/13), 16% (7/45) and 18% (30/169) in those reporting no, occasional and regular contact with residents. In contrast, staff working across different care homes (14/27, 52%) had a 3.0-fold (95% CI, 1.9-4.8; P<0.001) higher risk of SARS-CoV-2 positivity than staff working in single care homes (39/227, 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.

Keywords: COVID-19; Care homes; Occupational risk; SARS-CoV-2; Transmission.

Fig. 1

SARS-CoV-2 positivity among symptomatic and asymptomatic care home staff in 6 London care homes experiencing a COVID-19 outbreak.

Fig. 2

Maximum Likelihood phylogeny of 99 SARS-CoV-2 genomes from individuals within 6 London care homes. Coloured branches are used to indicate the care home, staff are annotated on the tree with (S), genomes from patients who died after testing positive for covid-19 are shown with (X). Unannotated tips in the phylogeny represent genomes from care home residents. P=permanent staff; R=regular contact with residents; O=occasional contact with residents; N=no contact with residents; Y=occasionally working across care homes; A=regularly working across care homes.