The role of spatial distance in SARS-CoV-2 nosocomial transmission

The nosocomial transmission of respiratory viruses causes significant disruption to hospital care, but the spatial dynamics of transmission on hospital wards are poorly understood.

We developed a model integrating computational fluid dynamics (CFD) simulations into an epidemiological reconstruction of virus transmission to quantify the relationship between SARS-CoV-2 transmission and the location of beds in medicine for the elderly wards.

Data from CFD simulations described a pattern in which exposure to an infected host decreased by approximately 40% for each additional metre of distance, with a further four-fold reduction when patients were in separate rooms. However, statistical inference suggested that only 72% (95% confidence interval 45%-96%) of the transmission events identified on wards could be explained by this model. Other cases of transmission occurred at distances too great to be consistent with the simulation model, suggesting that distance-independent mechanisms such as shared facilities or staff-mediated transmission had an important role in nosocomial transmission.

Our results suggest that while spatial separation reduces transmission risk, infection prevention and control strategies such as the use of single-bed rooms may be insufficient to prevent outbreaks. Comprehensive approaches to preventing nosocomial transmission, addressing multiple potential viral transmission pathways, are necessary.