COVID-19 Transmission Doubled in Care Homes Dependent on Agency Staff

Pavankumar Kamat

January 28, 2022

A modelling study published in  PLOS Computational Biology   suggests that care homes significantly dependent on agency staff have more than twice the likelihood of COVID-19 transmission among their residents.

Care homes in several countries, including the UK, strongly rely on temporary bank or agency staff due to persistent staff shortages, which have been further worsened during the COVID-19 pandemic.

Hybrid Simulation Model

Researchers at the University of Strathclyde constructed a hybrid model using two simulation approaches – systems dynamics (SD) and agent-based modelling (ABM), to assess the influence of agency/bank staff on COVID-19 transmission across a network of care homes.

Lead author and PhD candidate, Le Khanh Ngan Nguyen, said: "We used the SD model to study intra-facility transmission and ABM for inter-facility transmission. Combining both into a hybrid model can help address questions that are difficult to answer with a single approach."

The findings showed that in the absence of weekly testing, care homes using an average of 10% bank/agency staff had a relative risk [RR] of infection of 2.65 (95% CI 2.57 to 2.72) for residents compared with care homes not using bank/agency staff. The RR rose to 5.17 (95% CI 5.03 to 5.30) when the average level of bank/agency staff was increased to 20%. A similar trend was seen for RRs of outbreaks in care homes.

Influence of Testing, Staff Movement, and Bubbles

In the presence of high compliance to weekly testing (80%), the infection risk for residents in care homes using bank/agency staff declined, but remained significant (10% and 20% agency staff: RRs 1.28 and 1.64, respectively).

The study found that bank/agency staff who worked at multiple care homes had a higher risk of infection (RR 1.55; 95% CI 1.52 to 1.58) in scenarios of 0% compliance with testing, compared with permanent staff employed in single care homes. Even with high compliance (80%) to weekly testing, the risk of infection among the agency/bank staff still remained high (RR 1.35; 95% CI 1.32 to 1.38).

Across heterogeneous care homes, the use of bank/agency staff had the most profound impact on care homes with lower intra-facility transmission risks, higher staff-to-resident ratio, and fewer residents.

Additionally, the study found that forming bubbles of care homes and limiting agency staff to work exclusively in a bubble did little to curb on the transmission of COVID-19.

Commenting on the findings, co-author, Dr Itamar Megiddo from the University's department of management science, said: "Care homes are heavily reliant on agency/bank staff due to staff shortages. Consistent with other COVID-19 prevalence surveys in care homes in the UK, our findings would support policies for limiting the movement of staff working across multiple care homes if their testing compliance is low."

Le Khanh Ngan Nguyen and Itamar Megiddo were supported by the National Institute for Health Research. The authors report no competing interests.

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