Room-return ventilation and N95 respirator policies for reducing airborne pathogen exposure on hospital wards

Understanding interactions between the components of bundled mitigation measures can aid the prospective evaluation of hospital infection control programmes. This work provides a prospective, simulation-based examination of engineering controls (re-configured ventilation systems) designed to protect the healthcare workforce from airborne exposure on a ward for patients with acute respiratory infections such as coronavirus disease 2019 (COVID-19).

We developed and applied an agent-based computational model of nosocomial SARS-CoV-2 outbreaks to evaluate the combined effects of adding return ventilation in patient rooms (room-return ventilation) and a point-of-care N95 respirator policy where healthcare workers use respirators within patient rooms but do not wear them in other clinical areas (corridors and nurse stations).

By simulating COVID-19 transmission in the ward environment, our study demonstrates that modifications of air return configurations to limit the transport of viral quanta from patient rooms into adjacent corridors complement the effect of point-of-care respirator use, with synergistic effects. Indicative results show an increase in the benefit of N95 respirators on the time required for 50% of the ward's healthcare staff to become infected from 14.5 days 95% confidence interval (CI) [14.4, 14.7] (+262% [+260%, +265%]) using the baseline corridor-return ventilation configuration, to 40.1 days 95% CI [39.7, 40.4] (+576% [+570%, +581%]) using the modified room-return configuration, for a synergistic effect of more than two-fold.

The benefit of bundling room-return ventilation with the point-of-care N95 respirator policy is approximately equivalent to requiring N95 respirator use in all clinical areas (patient rooms, corridors, and nurse stations) with corridor-return ventilation.