Genomics Identifies Routes of COVID-19 Transmission in Care Homes

March 4, 2021
Killian Meara

By integrating genomic and temporal data, 409 viral clusters within 292 care homes were identified.

Investigators from the University of Cambridge and the Wellcome Sanger Institute have discovered the impact that COVID-19 has had on care homes and how the virus spreads in these types of settings. Results from the recent study were published in the journal eLife.

Care homes have been known to be high risk environments for the transmission of COVID-19 and outbreaks of the disease. Older populations are affected by the virus more compared to younger individuals, making care homes especially vulnerable places.

"Older people, particularly those in care homes who may be frail, are at particular risk from COVID-19, so it's essential we do all that we can to protect them," Estée Török, an Honorary Consultant at Addenbrooke's Hospital, Cambridge University Hospitals (CUH), and an Honorary Senior Visiting Fellow at the University of Cambridge said. "Preventing the introduction of new infections into care homes should be a key priority to limit outbreaks, alongside infection control efforts to limit transmission within care homes, including once an outbreak has been identified."

The investigators behind the study made use of both genome sequencing and detailed epidemiological information to examine how COVID-19 has impacted care homes. The team analyzed samples that were taken from 6,600 patients who tested positive for a SARS-CoV-2 infection. Of those, 1,167 were care home resident from 337 care homes in the east of England. The median age of the participants was 86 years old.

Findings from the study showed that nursing homes had more cases per home than residential homes. Although the median number of cases per care home was 2, 10 of the care homes in the study accounted for 164 of the cases. Less of the care home patients were admitted to the ICU but were more likely to die.

Additionally, 68% of the care home residents were admitted to the hospital throughout the course of the study, with 57% being due to an infection with COVID-19 and 6% of these acquiring the disease in the hospital. Several of the cases from the care homes clustered closely together on the phylogenetic tree with identical genomes or ones that were off by 1 base pair difference.

"Our data suggest that care home transmission was more resistant to lockdown measures than non-care home settings,” Gerry Tonkin-Hill from the Wellcome Sanger Institute said. “This may reflect the underlying vulnerability of the care home population, and the infection control challenges of nursing multiple residents who may also share communal living spaces.”