Table 3 Findings on facility location, facility design, staff compartmentalizing, temporary hired staff, nurse aides hours, and residence of staff

Bowblis, J. & Applebaum, R. (2020)

Measures assessed at three time points (April, May, June 2020) which were reported separately and combined. Findings adjusted for facility structural, occupancy and payer-mix, resident and case-mix characteristics, and rurality.

Care homes in rural areas, including rural cities, were consistently less likely to have a COVID-19 infected resident (marginal effect mean (SE) -0.117 (0.057), p < 0.05). There was no statistically significant association at any of the time points between rural location and having a high number of COVID-19 cases (defined as number of cases equal to at least 20% of beds) among facilities with at least one case.

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No consistent effects over three months were observed for use of temporary hired staff on the likelihood of having a resident with COVID-19 infection or having a high number of COVID-19 cases.

No consistent effects over three months on certified nurse aides hours per resident day on the likelihood of having a resident with COVID-19 infection or having a high number of COVID-19 cases.

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Drinka P.J. et al. (2004)

One building with more space per resident and 100% filtered air compared to three (older) buildings with fewer square feet per resident and 30–70% air circulated back into the buildings.

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No significant differences in infectious outbreaks of Influenza A observed between the facility buildings in five subsequent years

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Gorges, R.J. & Konetzka R.T. (2020)

High nursing aides hours defined as greater than 66th percentile of case-mix adjusted hours. Adjusted for facility size, ownership type, chain status, percentage of Medicaid residents, percentage of White residents, metropolitan status, and county cases per capita.

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High nurse aides hours were not associated with a COVID-19 outbreak but associated with lower risks for a larger outbreak (OR 0.790, SE 0.058, p < 0.01)

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He, M et al. (2020)

Facility age measured by years of operation. Adjusted for facility size and ownership type.

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No significant associations between facility age and one or more cases of COVID-19.

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Li, J. et al. (1996)

Multiple units refer to units in the same care home. Findings adjusted for infection control actions such as medical protocols and laboratory results, and authorities’ area offices.

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Having staff working at multiple units increased the risk of a nosocomial respiratory or gastrointestinal disease outbreak (RR 2.51, 95%CI 1.07–5.89) compared to having multiple units with separate staff.

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Lin, H. et al. (2011)

Number of outbreaks in care homes that supply isolation areas for infected residents part of infection control practices compared to care homes with no isolation areas

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Having an isolation area was not associated with lower risk of norovirus outbreaks.

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Rolland, Y. et al. (2020)

Staff compartmentalization defined as organization of the work so that the team works in small groups in one area of the care home with no physical connection with the other members of the team. Type of employment defined as permanent versus use of professional interim. Findings adjusted for care home administrative status and organization of the meals.

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Staff compartmentalization was associated with lower risk of COVID-19 outbreak (OR 0.17 95%CI 0.04–0.67, p < 0.01).

Use of professional interim was not associated with COVID-19 infection.

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Shallcross, L. et al. (2021)

Employment of other bank or agency staff used for nursing aides. Findings adjusted for social deprivation, provider type, staff-to-bed ratio, region, quality rating, staff sick pay, cohorting of staff, cleaning frequency, use of personal protective equipment, inability to isolate residents, new admissions and closure to visitors.

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Temporary employment a few times per month (OR 1.28, 95%CI 1.20–1.37, p < 0.0001), a few times per week (OR 1.08, 95%CI 1.01–1.16, p = 0.022) and on most days or every day (OR 1.08, 95%CI 1.00–1.16, p = 0.044) were all associated with higher proportion COVID-19 infection among residents compared to having no temporary staff.

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Shi, S. et al. (2020)

Home zip codes for all staff were obtained to assess the proportion of staff living in areas with high rates of COVID-19. Findings adjusted for resident characteristics (age, sex, medical conditions, activities of daily living scores, bowel incontinence, physical behaviours, and wandering.

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Staff living in a community with a high rate of COVID-19 was a significant predictor of COVID-19 infections in the care homes (OR 1.06, 95%CI 1.04–1.08)

Stall, N. et al. (2020)

Older design refers to below year 1972 design standards of larger room size, private washroom and single-occupancy. Findings adjusted for number of residents, chain ownership and staff-to-bed ratio.

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Older design standard (4-person rooms) was associated with greater risk of COVID-19 outbreaks among residents (RR 1.88, 95%CI 1.27–2.79)

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Sugg, M. et al. (2020)

Population density was used as a proxy for urban location. Findings adjusted for ownership, quality rating, population employment rates, ethnic groups, household size, and income per capita.

A higher risk of COVID-19 outbreaks was observed in care homes located in areas with higher population density per square mile (rate ratio 1.10, 95%CI 1.00–1.20, p = 0.042) across the USA. When examining the results regionally, the association remained significant in only 13 states.

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