Respiratory virus shedding in exhaled breath and efficacy of face masks

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 >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.一、数据采集 本研究的受试者于2013年3月至2016年5月期间，在香港某私立医院的普通门诊全年招募。发病3天内出现至少2项急性呼吸道疾病（Acute Respiratory Illness，ARI）症状（包括体温≥37.8℃、咳嗽、咽痛、流涕、头痛、肌痛及咳痰），且年龄≥11岁的个体符合参与本研究的资格。所有受试者均采集鼻拭子与单独的咽拭子样本，用于后续实验室病毒学确认检测。所有受试者同时填写问卷，记录年龄、性别、当前急性呼吸道疾病症状、基础疾病及吸烟史等基本信息。 符合入选标准的受试者随后在同一次门诊就诊期间，被要求采集30分钟的呼出气样本。呼出气样本采集前，所有受试者按1:1比例随机分为两组：采集过程中佩戴外科口罩（产品编号62356，金佰利，佐治亚州罗斯韦尔），或不佩戴口罩。受试者需自行佩戴外科口罩，若佩戴方式不正确，研究人员会提供正确佩戴的指导。采集过程中要求受试者正常呼吸，允许自然咳嗽，研究人员会记录咳嗽次数。随后邀请受试者采集另一组的第二次呼出气样本，但大部分受试者未同意停留进行第二次检测。 使用“G-II”生物气溶胶采集装置采集呼出气颗粒，并按粒径分为两组：粗颗粒组分（空气动力学直径>5μm，以下称为“呼吸道飞沫”，直径范围约1~100μm）与细颗粒组分（空气动力学直径≤5μm，以下称为“气溶胶”）。 首先使用诊断用病毒检测试剂盒xTAG呼吸道病毒Panel（雅培分子诊断，美国伊利诺伊州）对鼻拭子样本进行定性检测，可检出12种常见呼吸道病毒及其亚型，包括冠状病毒（NL63、OC43、229E及HKU1）、甲型流感病毒（通用型、H1及H3亚型）与乙型流感病毒、呼吸道合胞病毒（Respiratory Syncytial Virus，RSV）、副流感病毒（1~4型）、腺病毒、人偏肺病毒以及肠道病毒/鼻病毒。若该病毒检测试剂盒从鼻拭子样本中检出一种或多种目标呼吸道病毒，则对该受试者的所有样本（即鼻拭子、咽拭子、呼吸道飞沫与气溶胶样本）采用针对对应目标病毒的逆转录实时聚合酶链反应（reverse transcriptase real-time polymerase chain reaction，RT-PCR）进行检测，以测定样本中的病毒载量。感染性流感病毒则通过MDCK细胞病毒培养法进行鉴定。 最终共有246名受试者入组并提供了呼出气样本。在这246名受试者中，122名（50%）被随机分配至首次呼出气样本采集时不佩戴口罩组，124名（50%）分配至佩戴口罩组。其中49名（20%）受试者自愿提供了另一组的第二次呼出气样本采集。经RT-PCR检测，检出感染率最高的三类呼吸道病毒分别为冠状病毒（包含NL63、OC43、HKU1及229E亚型）、流感病毒与鼻病毒。因此本数据集包含这246名受试者的冠状病毒、流感病毒及鼻病毒载量数据，以及受试者基本信息与症状的匿名化数据。 二、数据处理 本次提供的数据仅经过最低限度的预处理。