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The following is a summary of “An agent-based model to assess the impact of shared staff and occupancy rate on infectious disease burden in nursing homes,” published in tihe April 2025 issue of BMC Infectious Diseases by Corkran et al. 

Infectious diseases were known to spread between nursing homes through asymptomatic staff working across multiple facilities, yet the transmission dynamics within and between homes remained underexplored.  

Researchers conducted a retrospective study to simulate infection dynamics using an agent-based model of 2 nursing homes expandable to a network with varying levels of shared staff.  

They focused on COVID-19 outbreaks in United States nursing homes and calibrated the agent-based model using state-level COVID-19 prevalence data and estimated the proportion of shared staff across each state. The simulations were performed using this model to assess the impact of different staff-sharing levels and found that lowering the percentage of shared staff to below 5% significantly limited infection spread between facilities. This effect was observed under conditions involving personal protective equipment use, rapid testing, and vaccination protocols.  

The results showed that when staff-sharing levels exceeded 30%, the effectiveness of mitigation strategies such as personal protective equipment, vaccination, and rapid testing decreased. The average infection prevalence stabilized across both nursing homes at higher staff-sharing levels. The hazard ratios for infection and mortality revealed greater susceptibility in nursing homes with elevated occupancy rates, indicating stronger negative effects from increased inter-facility staff movement.  

Investigators concluded that a greater degree of staff sharing between nursing homes raised the burden of infection, especially in high-occupancy facilities where resident density and staff interactions amplified transmission. 

Source: bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-025-10786-w