"To Prevent 'Droplet Infection' in Hospitals, Ventilation and Closing Doors Are Important"

A study has found that ventilation and keeping doors closed are crucial to preventing the hospital transmission of airborne infectious diseases like COVID-19.

Professor Eun-Jung Lee's research team from the Department of Infectious Diseases at Soonchunhyang University Seoul Hospital confirmed this through a retrospective epidemiological investigation of hospital outbreaks during the COVID-19 pandemic, announced on the 5th.

Eunjeong Lee, Professor of Infectious Diseases, Soonchunhyang University Seoul Hospital.

The research team conducted an epidemiological investigation related to a COVID-19 outbreak at a training hospital between February and March 2021. They analyzed a total of 283 COVID-19 infection cases and measured the hourly air pressure difference and air change rate (ACH) in the ward with the highest number of patients.

Airflow was evaluated using a droplet generator, indoor air quality sensors, and particle image velocimetry. Based on the index patient's room, the team also examined the window and door opening status of the corridor and the opposite ward rooms. The average air exchange rate in the patient rooms was 1.44 times per hour, and the supply air volume was 15.9% higher than the exhaust air volume, creating positive pressure.

The epidemiological investigation revealed that the COVID-19 spread occurred sequentially, moving from the room where the first patient was identified to the nearest rooms, especially spreading in the opposite direction. Aerodynamic experiments confirmed that droplet-like particles (droplet particles containing viruses) from the initial patient's room spread through the corridor and particularly through the patient room doors to the opposite rooms.

In conclusion, the spread of droplet particles between patient rooms was caused by the pressure difference between the rooms and the corridor. Therefore, to prevent COVID-19 transmission between rooms and corridors, ventilation within patient rooms should be maximized to increase air exchange rates, positive pressure in the rooms should be minimized by adjusting supply and exhaust air volumes, and patient room doors should be kept closed.

Professor Lee explained, "Ventilation is very important to prevent hospital transmission of respiratory viruses like COVID-19, and since ventilation systems alone are not perfect, this study proved that combining natural ventilation and keeping patient room doors closed is effective."

This study was published in the recent issue of the international journal Journal of Clinical Virology.

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