key: cord-0993963-q5egb5nz
authors: Su, Wen-Lin; Hung, Po-Pin; Lin, Chih-Pei; Chen, Li-Kuang; Lan, Chou-Chin; Yang, Mei-Chen; Peng, Ming-Yieh; Chao, You-Chen
title: Masks and closed-loop ventilators prevent environmental contamination by COVID-19 patients in negative-pressure environments
date: 2020-05-15
journal: J Microbiol Immunol Infect
DOI: 10.1016/j.jmii.2020.05.002
sha: dceb0be7d72c52606df0a7e20c9ced51f6bad490
doc_id: 993963
cord_uid: q5egb5nz

Abstract Herein, we report that nosocomial infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be mitigated by using surgical masks and closed looped ventilation for both non-critical and critical patients. These preventive measures resulted in no viral contamination of surfaces in negative pressure environments.

In early 2020, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread from China to the rest of the world, with most countries reporting nosocomial infections by the end of March. [1] [2] [3] Recently, a study conducted in Singapore has explored the mode of transmission and extent of environmental contamination in ambulatory patients. 4 A concurrent study revealed that turbulent gas clouds around critical patients intubated with mechanical ventilators increased the risk of viral transmission. 5 While SARS-CoV-2 can be detected on stainless steel or plastic for at least 2 to 3 days after initial contamination, 6 the actual viral load on surfaces in negative-pressure intensive care units (ICU) remains unknown. In this study, we examine viral contamination by SARS-CoV-2 positive patients on surfaces in the ICU and an ordinary ward for 9 days. 4 

The local surfaces around three patients were tested for viral contamination. Patient 1 was an 85-year-old male patient with critically severe SARS-CoV-2 pneumonia exhibiting respiratory failure and requiring mechanical ventilation. Patient 2, a 68-year-old male, and patient 3, a 60-year-old female, both presented simple SARS-CoV-2 bronchopneumonia. All three patients were admitted to a negative-pressure isolation room in either a medical ICU (patient 1) or an ordinary ward with 12 air exchanges per hour (patients 2 and 3). The negative-pressure differences for the ward area to buffer area and clean corridor to buffer area were -14 to -15 Pa and -8 to -9 Pa, respectively. The ward temperature was 23.2-23.9 and the relative humidity was 58.3-59.7%. For patient 1, a heat and moisture exchange (HME) filter (VH-3110 FHME, Great Group Medical CO., LTD., Taiwan) was installed between the tubing loop from the patient to the ventilator to prevent the virus entering the device. A closed suction device (T20005 PAHSCO, Pacific Hospital Supply CO., LTD., Taiwan) was also connected for sputum suction and to prevent viral transmission. A nebulizer device was omitted from this study to limit aerosolized contamination. For the two non-critical patients, surgical masks were redressed daily.

All areas were cleaned daily with a 1:10 dilution of 5% sodium hypochlorite, except the floor where a dilution ratio of 1:100 was used.

For patient 1 in the ICU, environmental samples were collected from 16 sites ( Figure   S1 ) before routine cleaning on the same dates as throat swabs, peritoneal dialysate, and anal swabs were collected (March 9, 12, and 18, 2020). Sterile throat swabs Figure S1 . Room layout of the negative-pressure ward in the medical intensive care unit. Numbered labels correspond to environmental sampling sites listed in Table 1 .

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The authors would like to acknowledge Miaw-Chi Peng, MSc, who performed the environmental sampling in the COVID-19 negative-pressure ICU and ordinary ward.