1
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Francis MR, Gidado S, Nuorti JP. The Risk of SARS-CoV-2 Transmission in Community Indoor Settings: A Systematic Review and Meta-analysis. J Infect Dis 2024; 230:e824-e836. [PMID: 38753340 PMCID: PMC11481457 DOI: 10.1093/infdis/jiae261] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 05/14/2024] [Indexed: 10/17/2024] Open
Abstract
BACKGROUND Quantifying the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in indoor settings is crucial for developing effective non-vaccine prevention strategies and policies. However, summary evidence on the transmission risks in settings other than households, schools, elderly care, and health care facilities is limited. We conducted a systematic review to estimate the secondary attack rates (SARs) of SARS-CoV-2 and the factors modifying transmission risk in community indoor settings. METHODS We searched Medline, Scopus, Web of Science, WHO COVID-19 Research Database, MedrXiv, and BiorXiv from 1 January 2020 to 20 February 2023. We included articles with original data for estimating SARS-CoV-2 SARs. We estimated the overall and setting-specific SARs using the inverse variance method for random-effects meta-analyses. RESULTS We included 34 studies with data on 577 index cases, 898 secondary cases, and 9173 contacts. The pooled SAR for community indoor settings was 20.4% (95% confidence interval [CI], 12.0%-32.5%). The setting-specific SARs were highest for singing events (SAR, 44.9%; 95% CI, 14.5%-79.7%), indoor meetings and entertainment venues (SAR, 31.9%; 95% CI, 10.4%-65.3%), and fitness centers (SAR, 28.9%; 95% CI, 9.9%-60.1%). We found no difference in SARs by index case, viral, and setting-specific characteristics. CONCLUSIONS The risk of SARS-CoV-2 transmission was highest in indoor settings where singing and exercising occurred. Effective mitigation measures such as assessing and improving ventilation should be considered to reduce the risk of transmission in high-risk settings. Future studies should systematically assess and report the host, viral, and setting-specific characteristics that may modify the transmission risks of SARS-CoV-2 and other respiratory viruses in indoor environments.
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Affiliation(s)
- Mark Rohit Francis
- Health Sciences Unit, Faculty of Social Sciences, Tampere University, Tampere, Finland
| | - Saheed Gidado
- Health Sciences Unit, Faculty of Social Sciences, Tampere University, Tampere, Finland
| | - J Pekka Nuorti
- Health Sciences Unit, Faculty of Social Sciences, Tampere University, Tampere, Finland
- Infectious Diseases and Vaccinations Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, Finland
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2
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Xu Z, Zhang H, Zhu M, Ji Y, Xue P, Xie J, Li Y, Zhang N. Human behavior-based COVID-19 transmission in two dining spaces. JOURNAL OF HAZARDOUS MATERIALS 2024; 480:135820. [PMID: 39298960 DOI: 10.1016/j.jhazmat.2024.135820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 08/27/2024] [Accepted: 09/10/2024] [Indexed: 09/22/2024]
Abstract
Since December 2019, the COVID-19 pandemic has rapidly disseminated globally, posing significant threats to the world. The dining spaces are high-risk indoor environments for the transmission of SARS-CoV-2, posing challenges for intervention and control. This study, based on surveillance videos from two COVID-19 outbreak cases in restaurants, obtained real data on human behaviors of close contact and surface touch. A respiratory infectious disease transmission model was developed, incorporating four transmission routes: short-range airborne, long-range airborne, fomite and large droplet. The results indicate that diners and staff spent 21.9 %-28.7 % and 17.5 %-27.8 % of their time on speaking, respectively, while spending 85.9 %-90.7 % and 83.4 %-87.6 % of their time on surface touching. The primary transmission routes were short-range (contributing 5.8 %-70.9 %) and long-range airborne (contributing 28.4 %-93.0 %), with fomite and large droplet routes contributing less than 12.0 %. Staff-only mask wearing reduced infection risk by 12.8 %-31.8 %. It is recommended that mandatory mask wearing for staff is necessary, while diners should wear masks as much as possible, and that the equivalent ventilation rate of clean fresh air is suggested to 30.0 m3/ (h·person). This study provides a scientific support to make non-pharmaceutical interventions in dinning spaces.
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Affiliation(s)
- Zhikang Xu
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Haochen Zhang
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Min Zhu
- 6th Medical Center of General Hospital of PLA, Beijing, China
| | - Ying Ji
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Peng Xue
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Jingchao Xie
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China
| | - Nan Zhang
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China.
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3
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Monika, Madugula SK, Kondabagil K, Kunwar A. Far-UVC (222 nm) irradiation effectively inactivates ssRNA, dsRNA, ssDNA, and dsDNA viruses as compared to germicidal UVC (254 nm). Photochem Photobiol 2024. [PMID: 38736273 DOI: 10.1111/php.13961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/23/2024] [Accepted: 04/24/2024] [Indexed: 05/14/2024]
Abstract
Ultraviolet-C (UVC) irradiation is being used as an effective approach for the disinfection of pathogenic viruses present in air, surfaces, and water. Recently, far-UVC radiation (222 nm) emitted by KrCl* (krypton-chloride) excimer lamps have been recommended for disinfecting high-risk public spaces to reduce the presence and transmission of infectious viruses owing to limited human health exposure risks as compared to germicidal UVC (254 nm). In this study, the UVC inactivation performances of individual filtered KrCl* excimer lamp (222 nm) and germicidal UVC lamp (254 nm) were determined against four viruses, bacteriophages MS2, Phi6, M13, and T4, having different genome compositions (ssRNA, dsRNA, ssDNA and dsDNA, respectively) and shapes (i.e., spherical (Phi6), linear (M13), and icosahedral (MS2 and T4)). Here, the disinfection efficacies of filtered KrCl* excimer lamp (222 nm) and germicidal UVC lamp (254 nm) were evaluated for highly concentrated virus droplets that mimic the virus-laden droplets released from the infected person and deposited on surfaces as fomites. Filtered KrCl* excimer (222 nm) showed significantly better inactivation against all viruses having different genome compositions and structures compared to germicidal UVC (254 nm). The obtained sensitivity against the filtered KrCl* excimer (222 nm) was found to be in the order, T4 > M13 > Phi6 > MS2 whereas for the germicidal UVC (254 nm) it was T4 > M13 > MS2 > Phi6. These results provide a strong basis to promote the use of filtered KrCl* excimer lamps (222 nm) in disinfecting contagious viruses and to limit the associated disease spread in public places and other high-risk areas.
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Affiliation(s)
- Monika
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
| | - Santhosh Kumar Madugula
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
| | - Kiran Kondabagil
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
| | - Ambarish Kunwar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
- Koita Centre for Digital Health (KCDH), Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
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4
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Lu YH, Wang RX, Liu HL, Lai ACK. Evaluating the Performance of UV Disinfection across the 222-365 nm Spectrum against Aerosolized Bacteria and Viruses. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6868-6877. [PMID: 38593035 DOI: 10.1021/acs.est.3c08675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Bioaerosols play a significant role in the transmission of many infectious diseases, especially in enclosed indoor environments. Ultraviolet (UV) disinfection has demonstrated a high efficacy in inactivating microorganisms suspended in the air. To develop more effective and efficient UV disinfection protocols, it is necessary to evaluate and optimize the effectiveness of UV disinfection against aerosolized bacteria and viruses across the entire UV spectrum. In this study, we evaluated the performance of UV disinfection across the UV spectrum, ranging from 222 to 365 nm, against aerosolized bacteria and viruses, including Escherichia coli, Staphylococcus epidermidis, Salmonella enterica, MS2, P22, and Phi6. Six commonly available UV sources, including gas discharge tubes and light-emitting diodes with different emission spectra, were utilized, and their performance in terms of inactivation efficacy, action spectrum, and energy efficiency was determined. Among these UV sources, the krypton chloride excilamp emitting at a peak wavelength of 222 nm was the most efficient in inactivating viral bioaerosols. A low-pressure mercury lamp emitting at 254 nm performed well on both inactivation efficacy and energy efficiency. A UV light-emitting diode emitting at 268 nm demonstrated the highest bacterial inactivation efficacy, but required approximately 10 times more energy to achieve an equivalent inactivation level compared with that of the krypton chloride excilamp and low-pressure mercury lamp. This study provides insights into UV inactivation on bioaerosols, which can guide the development of effective wavelength-targeted UV air disinfection technologies and may significantly help reduce bioaerosol transmission in public areas.
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Affiliation(s)
- Y H Lu
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| | - R X Wang
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| | - H L Liu
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| | - A C K Lai
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
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Huang W, Gao CX, Luo D, Wang Y, Zheng X, Liu C, Wang Y, Li Y, Qian H. Risk evaluation of venue types and human behaviors of COVID-19 outbreaks in public indoor environments: A systematic review and meta-analysis. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 341:122970. [PMID: 37979645 DOI: 10.1016/j.envpol.2023.122970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 10/03/2023] [Accepted: 11/14/2023] [Indexed: 11/20/2023]
Abstract
Despite increasing vaccination rates, the incidence of breakthrough infections with COVID-19 has increased due to the continued emergence of new variants of the SARS-CoV-2 coronavirus. Therefore, Non-pharmaceutical interventions remain the most effective measures for coping with the ever-changing pandemic. The lifting of compulsory interventions has made individuals primary responsibility for their own health, which highlights the importance of increasing awareness of the infection risk from the environment in which they live and their individual behaviors. We systematically searched PubMed, Web of Science, ScienceDirect, and Scopus on April 17, 2023, for all studies reporting COVID-19 outbreaks in public indoor venues. The study outcome was the attack rate. A total of 42 studies, which included cross-sectional studies, cohort studies, and case studies, reporting data on 1951 confirmed cases in 64 COVID-19 outbreaks satisfied the meta-analysis and were included in the review. A random-effect model was used in the meta-analysis, and subgroup analyses were conducted to investigate factors affecting attack rates. We found a strong level of evidence (p < 0.01) supporting a higher pooled attack rate in recreation-related venues (0.44, 95% CI: 0.30 to 0.60) than in work-related venues (0.21, 95% CI: 0.16 to 0.27). Compared to those outbreaks without that, outbreaks with high-intensity exercise, vocalization, contact behavior, or close body proximity had a higher attack rate of 0.51, 0.55, 0.33, and 0.39, respectively. Further studies suggest that different attack rates across different types of settings may be the result of heterogeneity in exposed people's behaviors. There were significant heterogeneities that may limit the interpretation of connections between influencing factors and outbreak outcomes. The identification of key behaviors that may contribute to transmission risk, and their correlation with venue type, has important implications for the development of future public health interventions and individual prevention strategies for respiratory infectious diseases such as COVID-19.
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Affiliation(s)
- Weiwei Huang
- School of Energy and Environment, Southeast University, Nanjing, China
| | - Caroline X Gao
- Centre for Youth Mental Health, The University of Melbourne, Parkville, VIC 3052, Australia; Orygen, Parkville, VIC 3052, Australia; Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, VIC 3004, Australia
| | - Danting Luo
- School of Energy and Environment, Southeast University, Nanjing, China; Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Yong Wang
- School of Energy and Environment, Southeast University, Nanjing, China
| | - Xiaohong Zheng
- School of Energy and Environment, Southeast University, Nanjing, China
| | - Cong Liu
- School of Energy and Environment, Southeast University, Nanjing, China
| | - Ying Wang
- Hubei Engineering Center for Infectious Disease Prevention, Control and Treatment, Wuhan, China; Department of Infection Management, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China; School of Public Health, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Hua Qian
- School of Energy and Environment, Southeast University, Nanjing, China; Hubei Engineering Center for Infectious Disease Prevention, Control and Treatment, Wuhan, China.
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6
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Braggion A, Dugerdil A, Wilson O, Hovagemyan F, Flahault A. Indoor Air Quality and COVID-19: A Scoping Review. Public Health Rev 2024; 44:1605803. [PMID: 38273885 PMCID: PMC10810127 DOI: 10.3389/phrs.2023.1605803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 11/09/2023] [Indexed: 01/27/2024] Open
Abstract
Objectives: The COVID-19 pandemic has been a major public health concern for the past 3 years. Scientific evidence on the relationship between SARS-CoV-2 infection and indoor air quality still needs to be demonstrated. This scoping review aims to study the association between air quality indoors and COVID-19. Methods: A scoping review analyzing the association between indoor air quality and epidemiological outcomes was conducted. Papers published between 1 January 2020 and 31 October 2022 were included. Hospital settings were excluded from the study. Results: Eight relevant articles met the inclusion criteria. Indoor settings included workplaces, schools, restaurants, and public transport. Types of ventilation used to improve indoor air quality were dilution methods (opening windows) and mechanical systems with or without filtration or purifier. CO2 sensors were employed in one study. All the studies showed a positive association between indoor air quality and its improvement and epidemiological indicators. Conclusion: The findings of this scoping review indicate that indoor air quality, which can be improved with ventilation methods, may reduce the risk of developing COVID-19. Ventilation could thus be viewed as a possible effective mitigating method.
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Affiliation(s)
- Axelle Braggion
- Institut de Santé Globale, Faculté de Médecine, Université de Genève, Geneva, Switzerland
| | - Adeline Dugerdil
- Institut de Santé Globale, Faculté de Médecine, Université de Genève, Geneva, Switzerland
| | - Olwen Wilson
- Institut de Santé Globale, Faculté de Médecine, Université de Genève, Geneva, Switzerland
- School of Public Policy, London School of Economics, London, United Kingdom
| | - Francesca Hovagemyan
- Institut de Santé Globale, Faculté de Médecine, Université de Genève, Geneva, Switzerland
| | - Antoine Flahault
- Institut de Santé Globale, Faculté de Médecine, Université de Genève, Geneva, Switzerland
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7
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Madhusudanan A, Iddon C, Cevik M, Naismith JH, Fitzgerald S. Non-pharmaceutical interventions for COVID-19: a systematic review on environmental control measures. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20230130. [PMID: 37611631 PMCID: PMC10446906 DOI: 10.1098/rsta.2023.0130] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 06/06/2023] [Indexed: 08/25/2023]
Abstract
The purpose of this review was to identify the effectiveness of environmental control (EC) non-pharmaceutical interventions (NPIs) in reducing transmission of SARS-CoV-2 through conducting a systematic review. EC NPIs considered in this review are room ventilation, air filtration/cleaning, room occupancy, surface disinfection, barrier devices, [Formula: see text] monitoring and one-way-systems. Systematic searches of databases from Web of Science, Medline, EMBASE, preprint servers MedRxiv and BioRxiv were conducted in order to identify studies reported between 1 January 2020 and 1 December 2022. All articles reporting on the effectiveness of ventilation, air filtration/cleaning, room occupancy, surface disinfection, barrier devices, [Formula: see text] monitoring and one-way systems in reducing transmission of SARS-CoV-2 were retrieved and screened. In total, 13 971 articles were identified for screening. The initial title and abstract screening identified 1328 articles for full text review. Overall, 19 references provided evidence for the effectiveness of NPIs: 12 reported on ventilation, 4 on air cleaning devices, 5 on surface disinfection, 6 on room occupancy and 1 on screens/barriers. No studies were found that considered the effectiveness of [Formula: see text] monitoring or the implementation of one-way systems. Many of these studies were assessed to have critical risk of bias in at least one domain, largely due to confounding factors that could have affected the measured outcomes. As a result, there is low confidence in the findings. Evidence suggests that EC NPIs of ventilation, air cleaning devices and reduction in room-occupancy may have a role in reducing transmission in certain settings. However, the evidence was usually of low or very low quality and certainty, and hence the level of confidence ascribed to this conclusion is low. Based on the evidence found, it was not possible to draw any specific conclusions regarding the effectiveness of surface disinfection and the use of barrier devices. From these results, we further conclude that community agreed standards for well-designed epidemiological studies with low risk of bias are needed. Implementation of such standards would enable more confident assessment in the future of the effectiveness of EC NPIs in reducing transmission of SARS-CoV-2 and other pathogens in real-world settings. This article is part of the theme issue 'The effectiveness of non-pharmaceutical interventions on the COVID-19 pandemic: the evidence'.
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Affiliation(s)
| | - Christopher Iddon
- Department of Civil, Environmental and Geomatic Engineering, University College London, WC1E 6BT, London, UK
| | - Muge Cevik
- Department of Infection and Global Health, School of Medicine, University of St Andrews, KY16 9TF, St Andrews, UK
| | | | - Shaun Fitzgerald
- Department of Engineering, University of Cambridge, CB2 1PZ, Cambridge, UK
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8
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Feng Y, Zhang Y, Ding X, Fan Y, Ge J. Multi-scale risk assessment and mitigations comparison for COVID-19 in urban public transport: A combined field measurement and modeling approach. BUILDING AND ENVIRONMENT 2023; 242:110489. [PMID: 37333517 PMCID: PMC10236904 DOI: 10.1016/j.buildenv.2023.110489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/31/2023] [Accepted: 06/02/2023] [Indexed: 06/20/2023]
Abstract
The outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has caused an unparalleled disruption to daily life. Given that COVID-19 primarily spreads in densely populated indoor areas, urban public transport (UPT) systems pose significant risks. This study presents an analysis of the air change rate in buses, subways, and high speed trains based on measured CO2 concentrations and passenger behaviors. The resulting values were used as inputs for an infection risk assessment model, which was used to quantitatively evaluate the effects of various factors, including ventilation rates, respiratory activities, and viral variants, on the infection risk. The findings demonstrate that ventilation has a negligible impact on reducing average risks (less than 10.0%) for short-range scales, but can result in a reduction of average risks by 32.1%-57.4% for room scales. When all passengers wear masks, the average risk reduction ranges from 4.5-folds to 7.5-folds. Based on our analysis, the average total reproduction numbers (R) of subways are 1.4-folds higher than buses, and 2-folds higher than high speed trains. Additionally, it is important to note that the Omicron variant may result in a much higher R value, estimated to be approximately 4.9-folds higher than the Delta variant. To reduce disease transmission, it is important to keep the R value below 1. Thus, two indices have been proposed: time-scale based exposure thresholds and spatial-scale based upper limit warnings. Mask wearing provides the greatest protection against infection in the face of long exposure duration to the omicron epidemic.
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Affiliation(s)
- Yinshuai Feng
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China
- Center for Balance Architecture, Zhejiang University, Hangzhou, China
- International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China
| | - Yan Zhang
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China
- International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China
| | - Xiaotian Ding
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China
- International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China
| | - Yifan Fan
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China
- Center for Balance Architecture, Zhejiang University, Hangzhou, China
- International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China
| | - Jian Ge
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China
- International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China
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Pal D, Amyot M, Liang C, Ariya PA. Real-time 4D tracking of airborne virus-laden droplets and aerosols. COMMUNICATIONS ENGINEERING 2023; 2:41. [PMCID: PMC10955884 DOI: 10.1038/s44172-023-00088-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 06/06/2023] [Indexed: 06/26/2024]
Abstract
There is currently no real-time airborne virus tracking method, hindering the understanding of rapid virus changes and associated health impacts. Nano-digital in-line holographic microscopy (Nano-DIHM) is a lensless technology that can directly obtain the interference patterns of objects by recording the scattered light information originating from the objects. Here, we provide evidence for real-time physicochemical tracking of virus-laden droplets and aerosols in the air using desktop label-free Nano-DIHM. The virus interference patterns, as single and ensemble particles, were imaged by the Nano-DIHM with 32.5 ms resolution. The next-generation Stingray and Octopus software was used to automate object detection, characterization and classification from the recorded holograms. The detection system was demonstrated to detect active MS2 bacteriophages, inactivated SARS-CoV-2 and RNA fragments, and an MS2 mixture with metallic and organic compounds. This work demonstrates the feasibility of using Nano-DIHM to provide rapid virus detection to improve transmission management in real time. Devendra Pal and coworkers report an imaging system using Nano-Digital in-line Holographic Microscopy (NanoDIHM) to detect airborne viruses in droplets and aerosols in real time. This system is able to detect various viruses in air, water and heterogeneous matrices within one minute, enabling real-time tracking of pollutant particles for efficient epidemic management.
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Affiliation(s)
- Devendra Pal
- Department of Atmospheric and Oceanic Sciences, McGill University, 805 Sherbrooke Street West, Montreal, QC H3A 0B9 Canada
| | - Marc Amyot
- Department of Biological Sciences, Univerité de Montréal, Complexe des Sciences, 1375 Avenue Thérèse-Lavoie-Roux, Montréal, QC H2V 0B3 Canada
| | - Chen Liang
- Department of Medicine, Division of Experimental Medicine, McGill University and Jewish General Hospital, 3755 Cote Sainte Catherine Rd., Montreal, QC G3T 1 E2 Canada
| | - Parisa A. Ariya
- Department of Atmospheric and Oceanic Sciences, McGill University, 805 Sherbrooke Street West, Montreal, QC H3A 0B9 Canada
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, QC H3A 2K6 Canada
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Park SY, Yu J, Bae S, Song JS, Lee SY, Kim JH, Jeong YS, Oh SM, Kim TH, Lee E. Ventilation strategies based on an aerodynamic analysis during a large-scale SARS-CoV-2 outbreak in an acute-care hospital. J Clin Virol 2023; 165:105502. [PMID: 37327553 DOI: 10.1016/j.jcv.2023.105502] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND This study aimed to investigate ventilation strategies to prevent nosocomial transmission of coronavirus disease 2019 (COVID-19). METHODS We conducted a retrospective epidemiological investigation of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak in a teaching hospital (February-March 2021). The largest outbreak ward was studied, and measurements were taken to determine the pressure difference and air change per hour (ACH) of the rooms. Airflow dynamics were assessed using an oil droplet generator, indoor air quality sensor, and particle image velocimetry in the index patient's room, corridor, and opposite rooms, by varying the opening and closing of windows and doors. RESULTS During the outbreak, 283 COVID-19 cases were identified. The SARS-CoV-2 spread occurred sequentially from the index room to the nearest room, especially the opposite. The aerodynamic study demonstrated that droplet-like particles in the index room diffused through the corridor and the opposite room through the opening door. The mean ACH of the rooms was 1.44; the air supply volume was 15.9% larger than the exhaust volume, forming a positive pressure. Closing the door prevented diffusion between adjacent rooms facing each other, and natural ventilation reduced the concentration of particles within the ward and minimised their spread to adjacent rooms. CONCLUSIONS Spread of droplet-like particles between rooms could be attributed to the pressure difference between the rooms and corridor. To prevent spread of SARS-CoV-2 between rooms, increasing the ACH in the room by maximising ventilation and minimising the positive pressure through supply/exhaust control and closing the room door are essential.
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Affiliation(s)
- Se Yoon Park
- Department of Hospital Medicine, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Republic of Korea; Centers for Digital Health, Yongin Severance Hospital, Yonsei University Health System, Yongin, Republic of Korea; Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Republic of Korea
| | - Jungyeon Yu
- Department of Building Research, Korea Institute of Civil Engineering and Building Technology, Goyang-Si, Republic of Korea
| | - Sanghwan Bae
- Department of Building Research, Korea Institute of Civil Engineering and Building Technology, Goyang-Si, Republic of Korea
| | - Jin Su Song
- Graduate School of Global Development & Enterpreneurship, Handong Global University, Pohang, Republic of Korea
| | - Shin Young Lee
- Division of Infectious Disease Response, Korea Diseases Control and Prevention Agency, Republic of Korea
| | - Jin Hwa Kim
- Infection Control Team, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea
| | - Yeon Su Jeong
- Infection Control Team, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea
| | - Sun Mi Oh
- Infection Control Team, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea
| | - Tae Hyong Kim
- Division of Infectious Diseases, Department of Internal Medicine, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul, Republic of Korea
| | - Eunjung Lee
- Division of Infectious Diseases, Department of Internal Medicine, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul, Republic of Korea.
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11
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Wong SC, Chan VWM, Yuen LLH, AuYeung CHY, Leung JOY, Li CK, Kwok MOT, So SYC, Chen JHK, Chiu KHY, Tam AR, Hung IFN, Kai-Wang To K, Lo JYC, Yuen KY, Cheng VCC. Infection of healthcare workers despite a high vaccination rate during the fifth wave of COVID-19 due to Omicron variant in Hong Kong. Infect Prev Pract 2023; 5:100261. [PMID: 36465098 PMCID: PMC9705264 DOI: 10.1016/j.infpip.2022.100261] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/15/2022] [Accepted: 11/22/2022] [Indexed: 12/03/2022] Open
Abstract
Background No nosocomial infection was recorded in our healthcare workers (HCWs) during the early phase of the coronavirus disease 2019 (COVID-19) pandemic. With the emergence of the Omicron variant of increased transmissibility, infection in HCWs occurred as expected. We aimed to study the epidemiology of infection in HCWs and to describe the infection control measures during the outbreak of the Omicron variant. Methods With daily rapid antigen testing and molecular confirmation test for COVID-19, infected HCWs were interviewed by infection control nurses (ICNs) to investigate the potential source of infection. The epidemiology of COVID-19 in Hong Kong served as reference. Results During the fifth wave of COVID-19 (31 December 2021 to 31 May 2022), 1,200,068 cases were reported (incidence 95 times higher than in preceding waves in Hong Kong; 162,103 vs 1,707 per million population respectively, P<0.001). The proportion of infected HCWs was significantly higher than that of the general population (24.9%, 1,607/6,452 vs 16.2%, 1,200,068/7,403,100 respectively; P<0.01). The proportion of infected non-clinical staff was significantly higher than that of clinical staff (31.8%, 536/1,687 vs 22.5%, 1,071/4,765 respectively; P<0.001). Of 82.8% (1,330/1,607) infected HCWs interviewed by ICNs, 99.5% (1,324/1,330) had been fully vaccinated; 49.5% (659/1,330) had no identifiable source; 40.7% (541/1,330) were probably infected from household members; 9.8% (130/1,330) had possible exposure to confirmed patients or HCWs, but no lapse in infection control measures or inappropriate use of personal protective equipment was recalled. Conclusion Omicron variant is highly transmissible such that breakthrough infection occurred despite high level of vaccination.
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Affiliation(s)
- Shuk-Ching Wong
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China
| | - Veronica Wing-Man Chan
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China
| | - Lithia Lai-Ha Yuen
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China
| | - Christine Ho-Yan AuYeung
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China
| | - Jessica Oi-Yan Leung
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China
| | - Chi-Kuen Li
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China
| | - Monica Oi-Tung Kwok
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China
| | - Simon Yung-Chun So
- Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China
| | - Jonathan Hon-Kwan Chen
- Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China
| | - Kelvin Hei-Yeung Chiu
- Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China
| | - Anthony Raymond Tam
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Ivan Fan-Ngai Hung
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Kelvin Kai-Wang To
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Janice Yee-Chi Lo
- Centre for Health Protection, Department of Health, Hong Kong Special Administrative Region, China
| | - Kwok-Yung Yuen
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Vincent Chi-Chung Cheng
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China,Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China,Corresponding author. Address: Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China. Tel.: +852 22552351, Fax: +852 23523698
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12
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Lau JJ, Cheng SMS, Leung K, Lee CK, Hachim A, Tsang LCH, Yam KWH, Chaothai S, Kwan KKH, Chai ZYH, Lo THK, Mori M, Wu C, Valkenburg SA, Amarasinghe GK, Lau EHY, Hui DSC, Leung GM, Peiris M, Wu JT. Real-world COVID-19 vaccine effectiveness against the Omicron BA.2 variant in a SARS-CoV-2 infection-naive population. Nat Med 2023; 29:348-357. [PMID: 36652990 PMCID: PMC9941049 DOI: 10.1038/s41591-023-02219-5] [Citation(s) in RCA: 87] [Impact Index Per Article: 87.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 01/13/2023] [Indexed: 01/19/2023]
Abstract
The SARS-CoV-2 Omicron variant has demonstrated enhanced transmissibility and escape of vaccine-derived immunity. Although first-generation vaccines remain effective against severe disease and death, robust evidence on vaccine effectiveness (VE) against all Omicron infections, irrespective of symptoms, remains sparse. We used a community-wide serosurvey with 5,310 subjects to estimate how vaccination histories modulated risk of infection in infection-naive Hong Kong during a large wave of Omicron BA.2 epidemic in January-July 2022. We estimated that Omicron infected 45% (41-48%) of the local population. Three and four doses of BNT162b2 or CoronaVac were effective against Omicron infection 7 days after vaccination (VE of 48% (95% credible interval 34-64%) and 69% (46-98%) for three and four doses of BNT162b2, respectively; VE of 30% (1-66%) and 56% (6-97%) for three and four doses of CoronaVac, respectively). At 100 days after immunization, VE waned to 26% (7-41%) and 35% (10-71%) for three and four doses of BNT162b2, and to 6% (0-29%) and 11% (0-54%) for three and four doses of CoronaVac. The rapid waning of VE against infection conferred by first-generation vaccines and an increasingly complex viral evolutionary landscape highlight the necessity for rapidly deploying updated vaccines followed by vigilant monitoring of VE.
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Affiliation(s)
- Jonathan J Lau
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Laboratory of Data Discovery for Health (D24H), Hong Kong SAR, China
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Samuel M S Cheng
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Kathy Leung
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Laboratory of Data Discovery for Health (D24H), Hong Kong SAR, China
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- The University of Hong Kong - Shenzhen Hospital, Shenzhen, China
| | - Cheuk Kwong Lee
- Hong Kong Red Cross Blood Transfusion Service, Hong Kong SAR, People's Republic of China
| | - Asmaa Hachim
- HKU-Pasteur Research Pole, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Leo C H Tsang
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Kenny W H Yam
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Sara Chaothai
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Kelvin K H Kwan
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Zacary Y H Chai
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Tiffany H K Lo
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Laboratory of Data Discovery for Health (D24H), Hong Kong SAR, China
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Masashi Mori
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Japan
| | - Chao Wu
- Department of Pathology and Immunology, Washington University School of Medicine at St. Louis, St. Louis, MO, USA
| | - Sophie A Valkenburg
- HKU-Pasteur Research Pole, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Gaya K Amarasinghe
- Department of Pathology and Immunology, Washington University School of Medicine at St. Louis, St. Louis, MO, USA
| | - Eric H Y Lau
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Laboratory of Data Discovery for Health (D24H), Hong Kong SAR, China
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - David S C Hui
- Department of Medicine and Therapeutics and Stanley Ho Centre for Emerging Infectious Diseases, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong SAR, China
| | - Gabriel M Leung
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Laboratory of Data Discovery for Health (D24H), Hong Kong SAR, China
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Malik Peiris
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Centre for Immunology and Infection, Hong Kong SAR, China
| | - Joseph T Wu
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
- Laboratory of Data Discovery for Health (D24H), Hong Kong SAR, China.
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
- The University of Hong Kong - Shenzhen Hospital, Shenzhen, China.
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13
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Lu YH, Wu H, Zhang HH, Li WS, Lai ACK. Synergistic disinfection of aerosolized bacteria and bacteriophage by far-UVC (222-nm) and negative air ions. JOURNAL OF HAZARDOUS MATERIALS 2023; 441:129876. [PMID: 36087531 DOI: 10.1016/j.jhazmat.2022.129876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 08/22/2022] [Accepted: 08/28/2022] [Indexed: 06/15/2023]
Abstract
Air ionizers and 222-nm krypton-chlorine (KrCl) excilamp have proven to be effective disinfection apparatus for bacteria and viruses with limited health risks. We determined inactivation efficiencies by operating them individually and in combined modules. Gram-positive and gram-negative bacteria, non-enveloped dsDNA virus, and enveloped dsRNA virus were examined in a designed air disinfection system. Our results showed that the bioaerosols were inactivated efficiently by negative ionizers and far-UVC (222-nm), either used individually or in combination. Among which the combined modules of negative ionizers and KrCl excilamp had the best disinfection performance for the bacteria. The aerosolized virus P22 and Phi 6 were more susceptible to 222-nm emitted by KrCl excilamp than negative air ions. Significant greater inactivation of bacterial bioaerosols were identified after treated by combined treatment of negative air ion and far-UVC for 2 minutes (Escherichia coli, 6.25 natural log (ln) reduction; Staphylococcus epidermidis, 3.66 ln reduction), as compared to the mean sum value of inactivation results by respective individual treatment of negative ionizers and KrCl excilamp (Escherichia coli, 4.34 ln; Staphylococcus epidermidis, 1.75 ln), indicating a synergistic inactivation effect. The findings provide important baseline data to support the design and development of safe and high-efficient disinfection systems.
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Affiliation(s)
- Y H Lu
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong China
| | - H Wu
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong China; Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong China
| | - H H Zhang
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong China
| | - W S Li
- School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong China
| | - A C K Lai
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong China.
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14
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Buonanno G, Ricolfi L, Morawska L, Stabile L. Increasing ventilation reduces SARS-CoV-2 airborne transmission in schools: A retrospective cohort study in Italy's Marche region. Front Public Health 2022; 10:1087087. [PMID: 36568748 PMCID: PMC9787545 DOI: 10.3389/fpubh.2022.1087087] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 11/25/2022] [Indexed: 12/13/2022] Open
Abstract
Introduction While increasing the ventilation rate is an important measure to remove inhalable virus-laden respiratory particles and lower the risk of infection, direct validation in schools with population-based studies is far from definitive. Methods We investigated the strength of association between ventilation and SARS-CoV-2 transmission reported among the students of Italy's Marche region in more than 10,000 classrooms, of which 316 were equipped with mechanical ventilation. We used ordinary and logistic regression models to explore the relative risk associated with the exposure of students in classrooms. Results and discussion For classrooms equipped with mechanical ventilation systems, the relative risk of infection of students decreased at least by 74% compared with a classroom with only natural ventilation, reaching values of at least 80% for ventilation rates >10 L s-1 student-1. From the regression analysis we obtained a relative risk reduction in the range 12%15% for each additional unit of ventilation rate per person. The results also allowed to validate a recently developed predictive theoretical approach able to estimate the SARS-CoV-2 risk of infection of susceptible individuals via the airborne transmission route. We need mechanical ventilation systems to protect students in classrooms from airborne transmission; the protection is greater if ventilation rates higher than the rate needed to ensure indoor air quality (>10 L s-1 student-1) are adopted. The excellent agreement between the results from the retrospective cohort study and the outcome of the predictive theoretical approach makes it possible to assess the risk of airborne transmission for any indoor environment.
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Affiliation(s)
- Giorgio Buonanno
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, Italy
- International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, QLD, Australia
| | - Luca Ricolfi
- Department of Psychology, University of Turin, Turin, Italy
- David Hume Foundation, Turin, Italy
| | - Lidia Morawska
- International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, QLD, Australia
| | - Luca Stabile
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, Italy
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15
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Wong SC, Au AKW, Lo JYC, Ho PL, Hung IFN, To KKW, Yuen KY, Cheng VCC. Evolution and Control of COVID-19 Epidemic in Hong Kong. Viruses 2022; 14:2519. [PMID: 36423128 PMCID: PMC9698160 DOI: 10.3390/v14112519] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/10/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022] Open
Abstract
Hong Kong SAR has adopted universal masking, social distancing, testing of all symptomatic and high-risk groups for isolation of confirmed cases in healthcare facilities, and quarantine of contacts as epidemiological control measures without city lockdown or border closure. These measures successfully suppressed the community transmission of pre-Omicron SARS-CoV-2 variants or lineages during the first to the fourth wave. No nosocomial SARS-CoV-2 infection was documented among healthcare workers in the first 300 days. The strategy of COVID-19 containment was adopted to provide additional time to achieve population immunity by vaccination. The near-zero COVID-19 situation for about 8 months in 2021 did not enable adequate immunization of the eligible population. A combination of factors was identified, especially population complacency associated with the low local COVID-19 activity, together with vaccine hesitancy. The importation of the highly transmissible Omicron variant kickstarted the fifth wave of COVID-19, which could no longer be controlled by our initial measures. The explosive fifth wave, which was partially contributed by vertical airborne transmission in high-rise residential buildings, resulted in over one million cases of infection. In this review, we summarize the epidemiology of COVID-19 and the infection control and public health measures against the importation and dissemination of SARS-CoV-2 until day 1000.
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Affiliation(s)
- Shuk-Ching Wong
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong SAR, China
| | - Albert Ka-Wing Au
- Centre for Health Protection, Department of Health, Hong Kong SAR, China
| | - Janice Yee-Chi Lo
- Centre for Health Protection, Department of Health, Hong Kong SAR, China
| | - Pak-Leung Ho
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Carol Yu Center for Infection, The University of Hong Kong, Hong Kong SAR, China
| | - Ivan Fan-Ngai Hung
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Kelvin Kai-Wang To
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Kwok-Yung Yuen
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Vincent Chi-Chung Cheng
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong SAR, China
- Department of Microbiology, Queen Mary Hospital, Hong Kong SAR, China
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16
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Zhang S, Niu D, Lin Z. Occupancy-aided ventilation for airborne infection risk control: Continuously or intermittently reduced occupancies? BUILDING SIMULATION 2022; 16:733-747. [PMID: 36373145 PMCID: PMC9638348 DOI: 10.1007/s12273-022-0951-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/24/2022] [Accepted: 10/09/2022] [Indexed: 05/25/2023]
Abstract
Ventilation is an important engineering measure to control the airborne infection risk of acute respiratory diseases, e.g., Corona Virus Disease 2019 (COVID-19). Occupancy-aided ventilation methods can effectively improve the airborne infection risk control performance with a sacrifice of decreasing working productivity because of the reduced occupancy. This study evaluates the effectiveness of two occupancy-aided ventilation methods, i.e., the continuously reduced occupancy method and the intermittently reduced occupancy method. The continuously reduced occupancy method is determined by the steady equation of the mass conservation law of the indoor contaminant, and the intermittently reduced occupancy method is determined by a genetic algorithm-based optimization. A two-scenarios-based evaluation framework is developed, i.e., one with targeted airborne infection risk control performance (indicated by the mean rebreathed fraction) and the other with targeted working productivity (indicated by the accumulated occupancy). The results show that the improvement in the airborne infection risk control performance linearly and quadratically increases with the reduction in the working productivity for the continuously reduced occupancy method and the intermittently reduced occupancy method respectively. At a given targeted airborne infection risk control performance, the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the working productivity by up to 92%. At a given targeted working productivity, the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the airborne infection risk control performance by up to 38%.
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Affiliation(s)
- Sheng Zhang
- School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an, China
| | - Dun Niu
- School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an, China
| | - Zhang Lin
- Division of Building Science and Technology, City University of Hong Kong, Hong Kong, China
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17
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Oksanen L, Auvinen M, Kuula J, Malmgren R, Romantschuk M, Hyvärinen A, Laitinen S, Maunula L, Sanmark E, Geneid A, Sofieva S, Salokas J, Veskiväli H, Sironen T, Grönholm T, Hellsten A, Atanasova N. Combining Phi6 as a surrogate virus and computational large-eddy simulations to study airborne transmission of SARS-CoV-2 in a restaurant. INDOOR AIR 2022; 32:e13165. [PMID: 36437671 PMCID: PMC10100099 DOI: 10.1111/ina.13165] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 09/30/2022] [Accepted: 10/08/2022] [Indexed: 05/18/2023]
Abstract
COVID-19 has highlighted the need for indoor risk-reduction strategies. Our aim is to provide information about the virus dispersion and attempts to reduce the infection risk. Indoor transmission was studied simulating a dining situation in a restaurant. Aerosolized Phi6 viruses were detected with several methods. The aerosol dispersion was modeled by using the Large-Eddy Simulation (LES) technique. Three risk-reduction strategies were studied: (1) augmenting ventilation with air purifiers, (2) spatial partitioning with dividers, and (3) combination of 1 and 2. In all simulations infectious viruses were detected throughout the space proving the existence long-distance aerosol transmission indoors. Experimental cumulative virus numbers and LES dispersion results were qualitatively similar. The LES results were further utilized to derive the evolution of infection probability. Air purifiers augmenting the effective ventilation rate by 65% reduced the spatially averaged infection probability by 30%-32%. This relative reduction manifests with approximately 15 min lag as aerosol dispersion only gradually reaches the purifier units. Both viral findings and LES results confirm that spatial partitioning has a negligible effect on the mean infection-probability indoors, but may affect the local levels adversely. Exploitation of high-resolution LES jointly with microbiological measurements enables an informative interpretation of the experimental results and facilitates a more complete risk assessment.
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Affiliation(s)
- Lotta Oksanen
- Department of Otorhinolaryngology and Phoniatrics – Head and Neck SurgeryHelsinki University HospitalHelsinkiFinland
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | | | - Joel Kuula
- Finnish Meteorological InstituteHelsinkiFinland
| | - Rasmus Malmgren
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | - Martin Romantschuk
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiLahtiFinland
| | | | | | - Leena Maunula
- Faculty of Veterinary Medicine, Food Hygiene and Environmental HealthUniversity of HelsinkiHelsinkiFinland
| | - Enni Sanmark
- Department of Otorhinolaryngology and Phoniatrics – Head and Neck SurgeryHelsinki University HospitalHelsinkiFinland
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Ahmed Geneid
- Department of Otorhinolaryngology and Phoniatrics – Head and Neck SurgeryHelsinki University HospitalHelsinkiFinland
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Svetlana Sofieva
- Finnish Meteorological InstituteHelsinkiFinland
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | - Julija Salokas
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | - Helin Veskiväli
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | - Tarja Sironen
- Department of Virology, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Department of Veterinary Biosciences, Faculty of Veterinary MedicineUniversity of HelsinkiHelsinkiFinland
| | | | | | - Nina Atanasova
- Finnish Meteorological InstituteHelsinkiFinland
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
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18
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Wang JX, Wu Z, Wang H, Zhong M, Mao Y, Li Y, Wang M, Yao S. Ventilation reconstruction in bathrooms for restraining hazardous plume: Mitigate COVID-19 and beyond. JOURNAL OF HAZARDOUS MATERIALS 2022; 439:129697. [PMID: 36104926 PMCID: PMC9335364 DOI: 10.1016/j.jhazmat.2022.129697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 07/11/2022] [Accepted: 07/27/2022] [Indexed: 05/20/2023]
Abstract
Converging evidence reports that the probability of vertical transmission patterns via shared drainage systems, may be responsible for the huge contactless community outbreak in high-rise buildings. Publications indicate that a faulty bathroom exhaust fan system is ineffective in removing lifted hazardous virus-laden aerosols from the toilet bowl space. Common strategies (boosting ventilation capability and applying disinfection tablets) seem unsustainable and remain to date untested. Using combined simulation and experimental approaches, we compared three ventilation schemes in a family bathroom including the traditional ceiling fan, floor fan, and side-wall fan. We found that the traditional ceiling fan was barely functional whereby aerosol particles were not being adequately removed. Conversely, a side-wall fan could function efficiently and an enhanced ventilation capability can have increased performance whereby nearly 80.9% of the lifted aerosol particles were removed. There exists a common, and easily-overlooked mistake in the layout of the bathroom, exposing occupants to a contactless vertical pathogen aerosol transmission route. Corrections and dissemination are thus imperative for the reconstruction of these types of family bathrooms. Our findings provide evidence for the bathroom and smart ventilation system upgrade, promoting indoor public health and human hygiene.
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Affiliation(s)
- Ji-Xiang Wang
- College of Electrical, Energy and Power Engineering, Yangzhou University, Yangzhou 225009, PR China; Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China.
| | - Zhe Wu
- College of Electrical, Energy and Power Engineering, Yangzhou University, Yangzhou 225009, PR China
| | - Hongmei Wang
- College of Electrical, Energy and Power Engineering, Yangzhou University, Yangzhou 225009, PR China
| | - Mingliang Zhong
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, PR China
| | - Yufeng Mao
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, PR China
| | - Yunyun Li
- School of Energy and Environment, Southeast University, Nanjing 210096, PR China
| | - Mengxiao Wang
- Department of Traditional Chinese Medicine, Tianjin Medical University General Hospital, Tianjin 300052, PR China
| | - Shuhuai Yao
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China; Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China.
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19
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Cheng VCC, Wong SC, Au AKW, Zhang C, Chen JHK, So SYC, Li X, Wang Q, Lu KK, Lung DC, Chuang VWM, Schuldenfrei E, Siu GKH, To KKW, Li Y, Yuen KY. Explosive outbreak of SARS-CoV-2 Omicron variant is associated with vertical transmission in high-rise residential buildings in Hong Kong. BUILDING AND ENVIRONMENT 2022; 221:109323. [PMID: 35765578 PMCID: PMC9225940 DOI: 10.1016/j.buildenv.2022.109323] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 06/14/2022] [Accepted: 06/16/2022] [Indexed: 05/12/2023]
Abstract
The phenomenon of vertical transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in high-rise residential buildings (HRRBs) is unique in our densely populated cosmopolitan city. The compulsory testing of a whole building under the scheme of restriction-testing declaration (RTD) during the fourth wave (non-Omicron variant) and fifth wave (mostly Omicron variant) of COVID-19 outbreak in Hong Kong allowed us to study the prevalence of this phenomenon, which may represent a form of airborne transmission. From 23 January 2021 to 24 March 2022, 25,450 (5.8%) of 436,397 residents from 223 (63.0%) of 354 HRRBs under RTD were test-positive for SARS-CoV-2. Using the clustering of cases among vertically aligned flats with shared drainage stack and lightwell as a surrogate marker of vertical transmission, the number of vertically aligned flats with positive COVID-19 cases was significantly higher in the fifth wave compared with the fourth wave (14.2%, 6471/45,531 vs 0.24%, 3/1272; p < 0.001; or 2212 vs 1 per-million-flats; p < 0.001). Excluding 22,801 residents from 38 HRRBs who were tested negative outside the 12-week periods selected in fourth and fifth waves, the positive rate among residents was significantly higher among residents during the fifth wave than the fourth wave (6.5%, 25,434/389,700 vs 0.07%, 16/23,896; p < 0.001). Within the flats with COVID-19 cases, the proportion of vertically aligned flats was also significantly higher in the fifth wave than in the fourth wave (95.6%, 6471/6766 vs 30.0%, 3/10, p < 0.001). The proportion of HRRBs with COVID-19 cases was significantly higher during the corresponding 12-week period chosen for comparison (78.2%, 219/280 vs 11.1%, 4/36; p < 0.001). Whole-genome phylogenetic analysis of 332 viral genomes showed that Omicron BA.2 was the predominant strain, supporting the high transmissibility of BA.2 by airborne excreta-aerosol route in HRRBs of Hong Kong.
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Affiliation(s)
- Vincent Chi-Chung Cheng
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China
- Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China
| | - Shuk-Ching Wong
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China
| | - Albert Ka-Wing Au
- Centre for Health Protection, Department of Health, Hong Kong Special Administrative Region, China
| | - Cheng Zhang
- Department of Mechanical Engineering, Faculty of Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Jonathan Hon-Kwan Chen
- Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China
| | - Simon Yung-Chun So
- Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China
| | - Xin Li
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Qun Wang
- Department of Mechanical Engineering, Faculty of Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Kelvin Keru Lu
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region, China
| | - David Christopher Lung
- Department of Pathology, Queen Elizabeth Hospital, Hong Kong Special Administrative Region, China
| | - Vivien Wai-Man Chuang
- Quality & Safety Division, Hospital Authority, Hong Kong Special Administrative Region, China
| | - Eric Schuldenfrei
- Department of Architecture, Faculty of Architecture, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Gilman Kit-Hang Siu
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region, China
| | - Kelvin Kai-Wang To
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Yuguo Li
- Department of Mechanical Engineering, Faculty of Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Kwok-Yung Yuen
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
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20
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Chen LL, Abdullah SMU, Chan WM, Chan BPC, Ip JD, Chu AWH, Lu L, Zhang X, Zhao Y, Chuang VWM, Au AKW, Cheng VCC, Sridhar S, Yuen KY, Hung IFN, Chan KH, To KKW. Contribution of low population immunity to the severe Omicron BA.2 outbreak in Hong Kong. Nat Commun 2022; 13:3618. [PMID: 35750868 PMCID: PMC9232516 DOI: 10.1038/s41467-022-31395-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/15/2022] [Indexed: 11/09/2022] Open
Abstract
Monitoring population protective immunity against SARS-CoV-2 variants is critical for risk assessment. We hypothesize that Hong Kong's explosive Omicron BA.2 outbreak in early 2022 could be explained by low herd immunity. Our seroprevalence study using sera collected from January to December 2021 shows a very low prevalence of neutralizing antibodies (NAb) against ancestral virus among older adults. The age group-specific prevalence of NAb generally correlates with the vaccination uptake rate, but older adults have a much lower NAb seropositive rate than vaccination uptake rate. For all age groups, the seroprevalence of NAb against Omicron variant is much lower than that against the ancestral virus. Our study suggests that this BA.2 outbreak and the exceptionally high case-fatality rate in the ≥80 year-old age group (9.2%) could be attributed to the lack of protective immunity in the population, especially among the vulnerable older adults, and that ongoing sero-surveillance is essential.
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Affiliation(s)
- Lin-Lei Chen
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China
| | - Syed Muhammad Umer Abdullah
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China
| | - Wan-Mui Chan
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China
| | - Brian Pui-Chun Chan
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China
| | - Jonathan Daniel Ip
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China
| | - Allen Wing-Ho Chu
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China
| | - Lu Lu
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China
| | - Xiaojuan Zhang
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China
| | - Yan Zhao
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China
| | | | - Albert Ka-Wing Au
- Centre for Health Protection, Department of Health, Hong Kong SAR, China
| | - Vincent Chi-Chung Cheng
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China.,Department of Microbiology, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China.,Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong SAR, China
| | - Siddharth Sridhar
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China.,Department of Microbiology, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China.,Department of Clinical Microbiology and Infection Control, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China
| | - Kwok-Yung Yuen
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China.,Department of Microbiology, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China.,Department of Clinical Microbiology and Infection Control, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China.,Centre for Virology, Vaccinology and Therapeutics, Hong Kong Science and Technology Park, Hong Kong SAR, China
| | - Ivan Fan-Ngai Hung
- Department of Medicine, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China
| | - Kwok-Hung Chan
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China.,Department of Clinical Microbiology and Infection Control, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China
| | - Kelvin Kai-Wang To
- State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, Pokfulam, The University of Hong Kong, Hong Kong SAR, China. .,Department of Microbiology, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China. .,Department of Clinical Microbiology and Infection Control, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China. .,Centre for Virology, Vaccinology and Therapeutics, Hong Kong Science and Technology Park, Hong Kong SAR, China.
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