Genomic sequencing has proved a high rate of single-source infections affecting care homes, and “ample opportunities for SARS-CoV-2 transmission between hospital and care home settings”, according to new research.
Of the cases 1,167 (18 per cent) were care home residents from 337 care homes, 193 of which were residential homes and 144 nursing homes. Most were based in the East of England.
Researchers tested the root cause of infections by creating ‘family trees’ – known as phylogenetic trees – that show how viral samples relate to each other. They found that for several care homes with the highest number of COVID cases, all cases clustered closely together on a phylogenetic tree with either identical genomes or just one base pair difference. This was consistent with a single outbreak spreading within the care home.
Researchers also found that 6 per cent of the COVID care home cases were suspected hospital-acquired infection, and 33 per cent followed discharged from hospital within seven days of a positive test.
By contrast, for several other care homes, cases were distributed across the phylogenetic tree, with more widespread genetic differences, suggesting that each of these cases was independent and not related to a shared transmission source.
Specifically, the team found two clusters that were linked to healthcare workers. One of these involved care home residents, a carer from that home and another from an unknown care home, paramedics and people living with them.
The second involved several care home residents and acute medical staff at Cambridge University Hospitals NHS Foundation Trust who cared for at least one of the residents. It was not possible to say where these clusters originated from and how the virus spread.
Underlying vulnerability of care home residents, and the infection control challenges of nursing multiple residents who may also share communal living spaces are cited as a reason for a slow rate of decline seen in the number of COVID-19 cases in care homes, researchers added.
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