文章基本信息

标题：Assessing the risk of COVID-19 from multiple pathways of exposure to SARS-CoV-2: Modeling in health-care settings and effectiveness of nonpharmaceutical interventions
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作者：Atsushi Mizukoshi ; Chikako Nakama ; Jiro Okumura 等
期刊名称：Environment International
印刷版ISSN：0160-4120
电子版ISSN：1873-6750
出版年度：2021
卷号：147
页码：106338
DOI：10.1016/j.envint.2020.106338
出版社：Pergamon
摘要：We assessed the risk of COVID-19 infection in a healthcare worker (HCW) from multiple pathways of exposure to SARS-CoV-2 in a health-care setting of short distance of 0.6 m between the HCW and a patient while caring, and evaluated the effectiveness of a face mask and a face shield using a model that combined previous infection-risk models. The multiple pathways of exposure included hand contact via contaminated surfaces and an HCW’s fingers with droplets, droplet spray, and inhalation of inspirable and respirable particles. We assumed a scenario of medium contact time (MCT) and long contact time (LCT) over 1 day of care by an HCW. SARS-CoV-2 in the particles emitted by coughing, breathing, and vocalization (only in the LCT scenario) by the patient were considered. The contribution of the risk of infection of an HCW by SARS-CoV-2 from each pathway to the sum of the risks from all pathways depended on virus concentration in the saliva of the patient. At a virus concentration in the saliva of 10 1 –10 5 PFU mL −1 concentration in the MCT scenario and 10 1 –10 4 PFU mL −1 concentration in the LCT scenario, droplet spraying was the major pathway (60%–86%) of infection, followed by hand contact via contaminated surfaces (9%–32%). At a high virus concentration in the saliva (10 6 –10 8 PFU mL −1 in the MCT scenario and 10 5 –10 8 PFU mL −1 in the LCT scenario), hand contact via contaminated surfaces was the main contributor (41%–83%) to infection. The contribution of inhalation of inspirable particles was 4%–10% in all assumed cases. The contribution of inhalation of respirable particles increased as the virus concentration in the saliva increased, and reached 5%–27% at the high saliva concentration (10 7 and 10 8 PFU mL −1 ) in the assumed scenarios using higher dose–response function parameter (0.246) and comparable to other pathways, although these were worst and rare cases. Regarding the effectiveness of nonpharmaceutical interventions, the relative risk (RR) of an overall risk for an HCW with an intervention vs. an HCW without intervention was 0.36–0.37, 0.02–0.03, and 99.9%. In addition, the RR for a face mask worn by the patient, and a face mask worn by the patient plus increase of air change rate from 2 h −1 to 6 h −1 was <1.0 × 10 −4 and <5.0 × 10 −5 , respectively in the same virus concentration in the saliva. Therefore, by modeling multiple pathways of exposure, the contribution of the infection risk from each pathway and the effectiveness of nonpharmaceutical interventions for COVID-19 were indicated quantitatively, and the importance of the use of a face mask and shield was confirmed.
关键词：COVID-19 ; Health-care ; Infection ; Multiple pathways ; Risk assessment ; SARS-CoV-2