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. 2021 Feb:152:105693.
doi: 10.1016/j.jaerosci.2020.105693. Epub 2020 Oct 15.

Breath-, air- and surface-borne SARS-CoV-2 in hospitals

Lian Zhou  1 , Maosheng Yao  2 , Xiang Zhang  3 , Bicheng Hu  4 , Xinyue Li  2 , Haoxuan Chen  2 , Lu Zhang  2 , Yun Liu  3 , Meng Du  5 , Bochao Sun  6 , Yunyu Jiang  7 , Kai Zhou  8 , Jie Hong  1 , Na Yu  9 , Zhen Ding  1 , Yan Xu  1 , Min Hu  2 , Lidia Morawska  10 , Sergey A Grinshpun  11 , Pratim Biswas  12 , Richard C Flagan  13 , Baoli Zhu  1   14 , Wenqing Liu  15 , Yuanhang Zhang  2
Affiliations

Breath-, air- and surface-borne SARS-CoV-2 in hospitals

Lian Zhou et al. J Aerosol Sci. 2021 Feb.

Abstract

The COVID-19 pandemic has brought an unprecedented crisis to the global health sector. When discharging COVID-19 patients in accordance with throat or nasal swab protocols using RT-PCR, the potential risk of reintroducing the infection source to humans and the environment must be resolved. Here, 14 patients including 10 COVID-19 subjects were recruited; exhaled breath condensate (EBC), air samples and surface swabs were collected and analyzed for SARS-CoV-2 using reverse transcription-polymerase chain reaction (RT-PCR) in four hospitals with applied natural ventilation and disinfection practices in Wuhan. Here we discovered that 22.2% of COVID-19 patients (n = 9), who were ready for hospital discharge based on current guidelines, had SARS-CoV-2 in their exhaled breath (~105 RNA copies/m3). Although fewer surface swabs (3.1%, n = 318) tested positive, medical equipment such as face shield frequently contacted/used by healthcare workers and the work shift floor were contaminated by SARS-CoV-2 (3-8 viruses/cm2). Three of the air samples (n = 44) including those collected using a robot-assisted sampler were detected positive by a digital PCR with a concentration level of 9-219 viruses/m3. RT-PCR diagnosis using throat swab specimens had a failure rate of more than 22% in safely discharging COVID-19 patients who were otherwise still exhaling the SARS-CoV-2 by a rate of estimated ~1400 RNA copies per minute into the air. Direct surface contact might not represent a major transmission route, and lower positive rate of air sample (6.8%) was likely due to natural ventilation (1.6-3.3 m/s) and regular disinfection practices. While there is a critical need for strengthening hospital discharge standards in preventing re-emergence of COVID-19 spread, use of breath sample as a supplement specimen could further guard the hospital discharge to ensure the safety of the public and minimize the pandemic re-emergence risk.

Keywords: Airborne transmission; COVID-19; Exhaled breath; SARS-CoV-2; Surface-borne.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Image 1
Graphical abstract
Fig. 1
Fig. 1
SARS-CoV-2 detection from EBC samples taken from the 9 recovering COVID-19 patients (Table S2); A) the recovering COVID-19 cases by age group; B) the recovering COVID-19 cases vs time of symptom onset to sample (TS2S) (day); C) throat swab tests for two COVID-19 patients. 2N = two negative results on the same date. P = positive result; NA = no tests available; ND = not detected; N = negative result.
Fig. 2
Fig. 2
Examples of digital PCR data from several air and surface samples collected during the campaign, including hospital corridor air (A), air cleaner ventilation outlet surface(B) ward air (C), and face shield surface (D). ORF1a/b gene detection was performed using FAM fluorescence probe, while N gene detection was performed using HEX fluorescence probe. For a signal amplitude above 3000, the corresponding signal was treated as a positive. Cy5 fluorescence probe was used the internal control.
See this image and copyright information in PMC

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