DOI: 10.5061/dryad.w9ghx3fkt
title: Respiratory virus shedding in exhaled breath and efficacy of face masks

description: We identified seasonal human coronaviruses, influenza viruses and
 rhinoviruses in the exhaled breath and coughs of children and adults with
 acute respiratory illness. Surgical face masks significantly reduced
 detection of influenza virus RNA in respiratory droplets and coronavirus
 RNA in aerosols, with a marginally significant reduction in coronavirus
 RNA in respiratory droplets. Our results indicate that surgical facemasks
 could prevent transmission of human coronaviruses and influenza viruses
 from symptomatic individuals.
description: Data collection
 Participants were recruited year-round from March 2013 through
 May 2016 in a general outpatient clinic of a private hospital in Hong
 Kong. Individuals who reported ≥2 symptoms of acute respiratory illness
 (ARI, including fever≥37.8ºC, cough, sore throat, runny nose, headache,
 myalgia and phlegm), within 3 days of illness onset and ≥11 years of age
 were eligible to participate in the study. All participants provided
 a nasal swab and a separate throat swab for subsequent virologic
 confirmation at the laboratory. All participants also completed a
 questionnaire to record basic information including age, sex, current ARI
 symptoms, medical conditions and smoking history. Eligible participants
 were then invited to provide an exhaled breath sample for 30 minutes in
 the same clinic visit. Prior to the exhaled breath
 collection, each participant was randomly allocated in a 1:1 ratio to
 either wearing a surgical face mask (Cat #62356, Kimberly-Clark, Roswell,
 Georgia) or not during the collection. Participants were asked to attach
 the surgical mask themselves, but instruction on how to wear the mask
 properly was given when the participant wore the mask incorrectly.
 Participants were instructed to breathe as normal during the collection,
 but (natural) coughing was allowed and the number of coughs was recorded
 by study staff. Participants were then invited to provide a second exhaled
 breath sample of the alternate type, but most participants did not agree
 to stay for a second measurement. Exhaled breath particles were captured
 and differentiated into two size fractions, the coarse fraction containing
 particles with aerodynamic diameter &gt;5μm (referred to here as
 ‘respiratory droplets’) which included droplets up to approximately 100 µm
 in diameter, and the fine fraction with particles ≤5μm (referred to here
 as ‘aerosols’) by the “G-II” bioaerosol collecting device.
 Nasal swab samples were first tested by a diagnostic-use viral
 panel, xTAG Respiratory Viral Panel (Abbott Molecular, Illinois, USA), to
 detect qualitatively twelve common respiratory viruses and subtypes
 including coronaviruses (NL63, OC43, 229E and HKU1), influenza A
 (non-specific, H1 and H3) and B viruses, respiratory syncytial virus
 (RSV), parainfluenza virus (types 1-4), adenovirus, human metapneumovirus,
 and enterovirus/rhinovirus. After one or more of the candidate respiratory
 viruses was detected by the Viral Panel from the nasal swab, all the
 samples from the same participant, i.e. the nasal swab, throat swab, the
 respiratory droplets and aerosols, were then tested with reverse
 transcriptase real-time polymerase chain reaction (RT-PCR) specific to the
 candidate virus(s) for determination of viral load in the samples.
 Infectious influenza virus was identified by viral culture using MDCK
 cells. Ultimately 246 individuals were enrolled and
 provided exhaled breath samples. Among these 246 participants, 122 (50%)
 participants were randomized to not wearing a face mask during the first
 exhaled breath collection and 124 (50%) participants randomized to wearing
 a face mask. 49 (20%) voluntarily provided a second exhaled breath
 collection of the alternate type. Three groups of respiratory viruses with
 highest frequency of infection were identified by RT-PCR, namely
 coronavirus (including NL63, OC43, HKU1 and 229E), influenza virus, and
 rhinovirus. Therefore, the present dataset included the viral load for
 coronavirus, influenza virus and rhinovirus, as well as anonymized data of
 participiants' basic information and symptoms, for these 246
 individuals. Data
 processing The data provided here was
 minimally processed.
description: Attached 10 files to generate all figures (except
 Extended Data Figure 1) and tables in:<br> Leung, N. H.
 L.<i> et al.</i> Respiratory virus shedding in exhaled breath
 and efficacy of face masks. <i>Nat. Med.</i>,
 doi:10.1038/s41591-020-0843-2 (2020). The 10
 files include:<br> 1)
 Dataset: G2resp_data_200324.csv<br> 2) Data
 dictionary: G2resp_dictionary_200324.csv<br> 3) R scripts: 1 x
 master script + 7 x sub-scripts Please run the
 master script which will then source all the
 sub-scripts: # Master<br>
 G2resp_00_master_script_200324.R # Transform viral load
 data<br> G2resp_01_Viral_shedding_transformation_200324.R
 # Extended Data Figure 2<br>
 G2resp_02_Weekly_number_of_respiratory_virus_infections_200324.R
 # Extended Data Figure 3<br>
 G2resp_03_Respiratory_virus_shedding_200324.R # Table
 1a, Supplementary Table 1<br>
 G2resp_04_Patient_characteristics_200324.R # Figure 1,
 Extended Data Figure 4, Extended Data Figure 5, Extended Data Figure
 9<br> # Table 1b, Supplementary Table 2, Supplementary Table 3
  <br> G2resp_05_Efficacy_of_surgical_face_masks_200324.R
 # Extended Data Figure 6, Extended Data Figure 7, Extended Data
 Figure 8<br>
 G2resp_06_Correlation_of_respiratory_viral_shedding_between_samples_200324.R # Supplementary Table 4, Supplementary Table 5, Supplementary Table 6 <br> G2resp_07_Factors_associated_with_respiratory_viral_shedding_200324.R