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Shyam S, Misra S, Mitra S, Mitra SK. Bacteria-surface interactions: role of impacting bacteria-laden droplets. SOFT MATTER 2024; 20:3425-3435. [PMID: 38623617 DOI: 10.1039/d4sm00196f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Understanding the interactions of pathogenic droplets with surfaces is crucial to biomedical applications. In this study, using E. coli as the model microbe, we investigate the impact of a bacteria-laden droplet on different substrates, both bare and antimicrobial. In doing so, we unveil the significance of kinetic energy and spreading parameters of the impacting droplet in determining the microbes' proliferation capabilities. Our results indicate an inverse relationship between the impact Weber number and the bacterial ability to proliferate. We reveal that the mechanical stress generated during impact impedes the capabilities of microbes present inside the droplet to create their progeny. Following an order analysis of the mechanical stress generated, we argue that the impact does not induce lysis-driven cell death of the bacteria; rather, it promotes a stress-driven transition of viable bacteria to a viable-but-non-culturable (VBNC) state. Furthermore, variations in the concentration of particles on the antimicrobial surfaces revealed the role of the post-impact spreading behaviour in dictating bacterial proliferation capabilities. Contrary to the conventional notion, we demonstrate that during the early stages of interaction, a bare substrate may outperform an antibacterial substrate in the inactivation of the bacterial load. Finally, we present an interaction map illustrating the complex relationship between bacterial colony-forming units, bactericide concentration on the surface, and the impact Weber number. We believe that the inferences of the study, highlighting the effect of mechanical stresses on the soft cell wall of microbes, could be a useful design consideration for the development of antimicrobial surfaces.
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Affiliation(s)
- Sudip Shyam
- Micro & Nano-Scale Transport Laboratory, Waterloo Institute for Nanotechnology, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
| | - Sirshendu Misra
- Micro & Nano-Scale Transport Laboratory, Waterloo Institute for Nanotechnology, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
| | - Surjyasish Mitra
- Micro & Nano-Scale Transport Laboratory, Waterloo Institute for Nanotechnology, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
| | - Sushanta K Mitra
- Micro & Nano-Scale Transport Laboratory, Waterloo Institute for Nanotechnology, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
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Tu J, Wang Y, Ye X, Wang Y, Zou Y, Jia L, Yang S, Yu R, Liu W, Huang P. Gut microbial features may influence antiviral IgG levels after vaccination against viral respiratory infectious diseases: the evidence from two-sample bidirectional mendelian randomization. BMC Infect Dis 2024; 24:431. [PMID: 38654203 PMCID: PMC11036767 DOI: 10.1186/s12879-024-09189-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 03/04/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND Vaccination is effective in preventing viral respiratory infectious diseases through protective antibodies and the gut microbiome has been proven to regulate human immunity. This study explores the causal correlations between gut microbial features and serum-specific antiviral immunoglobulin G (IgG) levels. METHODS We conduct a two-sample bidirectional Mendelian randomization (MR) analysis using genome-wide association study (GWAS) summary data to explore the causal relationships between 412 gut microbial features and four antiviral IgG (for influenza A, measles, rubella, and mumps) levels. To make the results more reliable, we used four robust methods and performed comprehensive sensitivity analyses. RESULTS The MR analyses revealed 26, 13, 20, and 18 causal associations of the gut microbial features influencing four IgG levels separately. Interestingly, ten microbial features, like genus Collinsella, species Bifidobacterium longum, and the biosynthesis of L-alanine have shown the capacity to regulate multiple IgG levels with consistent direction (rise or fall). The reverse MR analysis suggested several potential causal associations of IgG levels affecting microbial features. CONCLUSIONS The human immune response against viral respiratory infectious diseases could be modulated by changing the abundance of gut microbes, which provided new approaches for the intervention of viral respiratory infections.
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Affiliation(s)
- Junlan Tu
- Department of Epidemiology, Center for Global Health, School of Public Health, National Vaccine Innovation Platform, Nanjing Medical University, 211166, Nanjing, China
| | - Yidi Wang
- Department of Epidemiology, Center for Global Health, School of Public Health, National Vaccine Innovation Platform, Nanjing Medical University, 211166, Nanjing, China
| | - Xiangyu Ye
- Department of Epidemiology, Center for Global Health, School of Public Health, National Vaccine Innovation Platform, Nanjing Medical University, 211166, Nanjing, China
| | - Yifan Wang
- Department of Infectious Disease, Jurong Hospital Affiliated to Jiangsu University, Jurong, China
| | - Yixin Zou
- Department of Epidemiology, Center for Global Health, School of Public Health, National Vaccine Innovation Platform, Nanjing Medical University, 211166, Nanjing, China
| | - Linna Jia
- Department of Epidemiology, Center for Global Health, School of Public Health, National Vaccine Innovation Platform, Nanjing Medical University, 211166, Nanjing, China
| | - Sheng Yang
- Department of Biostatistics, Center for Global Health, School of Public Health, National Vaccine Innovation Platform, Nanjing Medical University, 211166, Nanjing, China
| | - Rongbin Yu
- Department of Epidemiology, Center for Global Health, School of Public Health, National Vaccine Innovation Platform, Nanjing Medical University, 211166, Nanjing, China.
| | - Wei Liu
- Department of Epidemiology, Center for Global Health, School of Public Health, National Vaccine Innovation Platform, Nanjing Medical University, 211166, Nanjing, China.
- Beijing Institute of Microbiology and Epidemiology, State Key Laboratory of Pathogen and Biosecurity, 100071, Beijing, China.
| | - Peng Huang
- Department of Epidemiology, Center for Global Health, School of Public Health, National Vaccine Innovation Platform, Nanjing Medical University, 211166, Nanjing, China.
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Rockey NC, Le Sage V, Marr LC, Lakdawala SS. Seasonal influenza viruses decay more rapidly at intermediate humidity in droplets containing saliva compared to respiratory mucus. Appl Environ Microbiol 2024; 90:e0201023. [PMID: 38193683 PMCID: PMC10880610 DOI: 10.1128/aem.02010-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 11/27/2023] [Indexed: 01/10/2024] Open
Abstract
Expulsions of virus-laden aerosols or droplets from the oral and nasal cavities of an infected host are an important source of onward respiratory virus transmission. However, the presence of infectious influenza virus in the oral cavity during infection has not been widely considered, and thus, little work has explored the environmental persistence of influenza virus in oral cavity expulsions. Using the ferret model, we detected infectious virus in the nasal and oral cavities, suggesting that the virus can be expelled into the environment from both anatomical sites. We also assessed the stability of two influenza A viruses (H1N1 and H3N2) in droplets of human saliva or respiratory mucus over a range of relative humidities. We observed that influenza virus infectivity decays rapidly in saliva droplets at intermediate relative humidity, while viruses in airway surface liquid droplets retain infectivity. Virus inactivation was not associated with bulk protein content, salt content, or droplet drying time. Instead, we found that saliva droplets exhibited distinct inactivation kinetics during the wet and dry phases at intermediate relative humidity, and droplet residue morphology may lead to the elevated first-order inactivation rate observed during the dry phase. Additionally, distinct differences in crystalline structure and nanobead localization were observed between saliva and airway surface liquid droplets. Together, our work demonstrates that different respiratory fluids exhibit unique virus persistence profiles and suggests that influenza viruses expelled from the oral cavity may contribute to virus transmission in low- and high-humidity environments.IMPORTANCEDetermining how long viruses persist in the environment is important for mitigating transmission risk. Expelled infectious droplets and aerosols are composed of respiratory fluids, including saliva and complex mucus mixtures, but how well influenza viruses survive in such fluids is largely unknown. Here, we find that infectious influenza virus is present in the oral cavity of infected ferrets, suggesting that saliva-containing expulsions can play a role in onward transmission. Additionally, influenza virus in droplets composed of saliva degrades more rapidly than virus within respiratory mucus. Droplet composition impacts the crystalline structure and virus localization in dried droplets. These results suggest that viruses from distinct sites in the respiratory tract could have variable persistence in the environment, which will impact viral transmission fitness.
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Affiliation(s)
- Nicole C. Rockey
- Department of Microbiology and Molecular Genetics, The University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Civil and Environmental Engineering, Duke University, Durham, North Carolina, USA
| | - Valerie Le Sage
- Department of Microbiology and Molecular Genetics, The University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Linsey C. Marr
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, USA
| | - Seema S. Lakdawala
- Department of Microbiology and Molecular Genetics, The University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
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4
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Alavinejad M, Tosato M, Bragazzi NL, McCarthy Z, Wu J, Bourouiba L. Markers of community outbreak and facility type for mitigation of COVID-19 in long-term care homes in Ontario, Canada: Insights and implications from a time-series analysis. Ann Epidemiol 2024; 90:9-20. [PMID: 37690739 DOI: 10.1016/j.annepidem.2023.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 08/17/2023] [Accepted: 08/19/2023] [Indexed: 09/12/2023]
Abstract
PURPOSE The resident deaths among Long Term Care Home (LTCH) accounted for more than 65% of total deaths in the province of Ontario, Canada, during March 29 to June 3, 2020, yet not all LTCHs were severely affected. METHODS We carried out a retrospective cohort study, with case control for questions for which data allowed, with LTCH COVID-19 databases obtained from Ontario's Ministry of Long Term Care. We performed a combined temporal and spatial data analysis of COVID-19 cases and deaths among LTCH residents, identified trends, contributing factors, and early markers of LTCH outbreak severity. RESULTS Our analysis shows that for-profit LTCHs had higher death-to-bed ratio, also with an average rate of increase of death-to-bed ratio higher for for-profit homes than other types of management. We find from uni- and multi-variable analyses (linear and nonlinear) that staff infection has the strongest association with death-to-bed ratio from among the descriptor variables considered, reflecting the risk of the disease in the health region/community. We also identify a delay of up to 8 days between the trends in fatalities among individuals outside LTCHs and that of LTCH residents. We did find an association between policy change to single LTCH/staff and reduction in weekly LTCH resident death, albeit with an expected time delay of about 7-10 days. CONCLUSIONS The association between the risk of COVID-19 in the health region and the deaths among LTCH residents, and the delay between fatality among individuals residing outside and inside LTCHs suggests that fatality in a health region could be a predictor of outbreak in LTCHs within the same health region.
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Affiliation(s)
- M Alavinejad
- Mathematical Modelling of COVID-19 Task Force, Fields Laboratory of Mathematics for Public Health, University of Toronto, Ontario, Canada; Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada
| | - M Tosato
- Mathematical Modelling of COVID-19 Task Force, Fields Laboratory of Mathematics for Public Health, University of Toronto, Ontario, Canada; Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada
| | - N L Bragazzi
- Mathematical Modelling of COVID-19 Task Force, Fields Laboratory of Mathematics for Public Health, University of Toronto, Ontario, Canada; Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada
| | - Z McCarthy
- Mathematical Modelling of COVID-19 Task Force, Fields Laboratory of Mathematics for Public Health, University of Toronto, Ontario, Canada; Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada
| | - J Wu
- Mathematical Modelling of COVID-19 Task Force, Fields Laboratory of Mathematics for Public Health, University of Toronto, Ontario, Canada; Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada
| | - L Bourouiba
- Mathematical Modelling of COVID-19 Task Force, Fields Laboratory of Mathematics for Public Health, University of Toronto, Ontario, Canada; The Fluid Dynamics of Disease Transmission Laboratory, Massachusetts In stitute of Technology, Cambridge, MA, USA.
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5
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Han J, Lee H. Control Volume Analysis of the Infusion Rate in Cephalic and Median Cubital Veins Based on Infusion Bag Height and Peripheral Venous Catheter Inner Diameter: Application of Bernoulli's Equation and Consideration of Frictional Forces. J Multidiscip Healthc 2023; 16:3609-3618. [PMID: 38034878 PMCID: PMC10684996 DOI: 10.2147/jmdh.s409050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 10/27/2023] [Indexed: 12/02/2023] Open
Abstract
Purpose This pilot study aimed to provide basic data on intravenous infusion nursing by analyzing the infusion rate in the cephalic and median cubital veins depending on the height of the infusion bag and inner diameter of the peripheral venous catheter (PVC). Methods While infusing 0.9% normal saline at 22 °C (room temperature) into elbow cephalic and median cubital veins, the infusion rate may be controlled by adjusting the fluid height and PVC diameter. To assess the validity of the laminar flow assumption, the study estimated the Reynolds number (Re) using the velocity obtained by applying Bernoulli's equation considering the friction coefficient. Results At a constant fluid height, the infusion rate increased with increasing PVC diameter. At a constant PVC diameter, the infusion rate increased with increasing fluid height. In a comparison between the cephalic and median cubital veins at constant fluid height and PVC diameter, the solution was infused at a higher rate into the cephalic vein, which was under lower venous pressure. Conclusion The analysis of the infusion rate according to fluid height and PVC diameter provided basic data on intravenous infusion nursing. The results are expected to provide evidence for the standardization of intravenous infusion nursing.
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Affiliation(s)
- Jeongwon Han
- College of Nursing Science, Kyung Hee University, Seoul, Republic of Korea
| | - Hanna Lee
- Department of Nursing, Gangneung-Wonju National University, Gangwon‑do, Republic of Korea
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6
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Le Sage V, Lowen AC, Lakdawala SS. Block the Spread: Barriers to Transmission of Influenza Viruses. Annu Rev Virol 2023; 10:347-370. [PMID: 37308086 DOI: 10.1146/annurev-virology-111821-115447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Respiratory viruses, such as influenza viruses, cause significant morbidity and mortality worldwide through seasonal epidemics and sporadic pandemics. Influenza viruses transmit through multiple modes including contact (either direct or through a contaminated surface) and inhalation of expelled aerosols. Successful human to human transmission requires an infected donor who expels virus into the environment, a susceptible recipient, and persistence of the expelled virus within the environment. The relative efficiency of each mode can be altered by viral features, environmental parameters, donor and recipient host characteristics, and viral persistence. Interventions to mitigate transmission of influenza viruses can target any of these factors. In this review, we discuss many aspects of influenza virus transmission, including the systems to study it, as well as the impact of natural barriers and various nonpharmaceutical and pharmaceutical interventions.
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Affiliation(s)
- Valerie Le Sage
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Anice C Lowen
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA;
| | - Seema S Lakdawala
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA;
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7
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Clements N, Arvelo I, Arnold P, Heredia NJ, Hodges UW, Deresinski S, Cook PW, Hamilton KA. Informing Building Strategies to Reduce Infectious Aerosol Transmission Risk by Integrating DNA Aerosol Tracers with Quantitative Microbial Risk Assessment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:5771-5781. [PMID: 37000413 DOI: 10.1021/acs.est.2c08131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Using aerosol-based tracers to estimate risk of infectious aerosol transmission aids in the design of buildings with adequate protection against aerosol transmissible pathogens, such as SARS-CoV-2 and influenza. We propose a method for scaling a SARS-CoV-2 bulk aerosol quantitative microbial risk assessment (QMRA) model for impulse emissions, coughing or sneezing, with aerosolized synthetic DNA tracer concentration measurements. With point-of-emission ratios describing relationships between tracer and respiratory aerosol emission characteristics (i.e., volume and RNA or DNA concentrations) and accounting for aerosolized pathogen loss of infectivity over time, we scale the inhaled pathogen dose and risk of infection with time-integrated tracer concentrations measured with a filter sampler. This tracer-scaled QMRA model is evaluated through scenario testing, comparing the impact of ventilation, occupancy, masking, and layering interventions on infection risk. We apply the tracer-scaled QMRA model to measurement data from an ambulatory care room to estimate the risk reduction resulting from HEPA air cleaner operation. Using DNA tracer measurements to scale a bulk aerosol QMRA model is a relatively simple method of estimating risk in buildings and can be applied to understand the impact of risk mitigation efforts.
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Affiliation(s)
- Nicholas Clements
- Paul M. Rady Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309, United States
| | - Ilan Arvelo
- SafeTraces, Inc., Pleasanton, California 94588, United States
| | - Phil Arnold
- SafeTraces, Inc., Pleasanton, California 94588, United States
| | | | - Ulrike W Hodges
- SafeTraces, Inc., Pleasanton, California 94588, United States
| | - Stan Deresinski
- Stanford University School of Medicine, Stanford, California 94305, United States
| | - Peter W Cook
- Independent researcher, Atlanta, Georgia 30333, United States
| | - Kerry A Hamilton
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- The Biodesign Institute Center for Environmental Health Engineering, Arizona State University, Tempe, Arizona 85281, United States
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8
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Strohm EM, Sathiyamoorthy K, Bok T, Nusrat O, Kolios MC. Air-Coupled Photoacoustic Detection of Airborne Particulates. INTERNATIONAL JOURNAL OF THERMOPHYSICS 2023; 44:67. [PMID: 36909209 PMCID: PMC9990552 DOI: 10.1007/s10765-023-03169-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
In this study, we present a novel method to detect airborne particulates using air-coupled photoacoustics, with a goal toward detecting viral content in respiratory droplets. The peak photoacoustic frequency emitted from micrometer-sized particulates is over 1000 MHz, but at this frequency, the signals are highly attenuated in air. Measurements were taken using a thin planar absorber and ultrasound transducers with peak sensitivity between 50 kHz and 2000 kHz and a 532 nm pulsed laser to determine the optimum detection frequency. 350 kHz to 500 kHz provided the highest amplitude signal while minimizing attenuation in air. To simulate the expulsion of respiratory droplets, an atomizer device was used to spray droplets into open air through a pulsed laser. Droplets were composed of water, water with acridine orange dye, and water with gold nanoparticles. The dye and nanoparticles were chosen due to their similarity in the UV absorption peaks when compared to RNA. Using a 260 nm laser, the average photoacoustic signal from water was the highest, and then the signal decreased with dye or nanoparticles. Increasing absorber concentrations within their respective solutions resulted in a decreasing photoacoustic signal, which is opposite to our expectations. Monte Carlo simulations demonstrated that depending on the droplet dimensions, water droplets focus photons to create a localized fluence elevation. Absorbers within the droplet can inhibit photon travel through the droplet, decreasing the fluence. Photoacoustic signals are created through optical absorption within the droplet, potentially amplified with the localized fluence increase through the droplet focusing effect, with a trade-off in signal amplitude depending on the absorber concentration.
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Affiliation(s)
- Eric M. Strohm
- Department of Physics, Toronto Metropolitan University (Formerly Ryerson University), Toronto, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael’s Hospital, Toronto, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Canada
| | - Krishnan Sathiyamoorthy
- Department of Physics, Toronto Metropolitan University (Formerly Ryerson University), Toronto, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael’s Hospital, Toronto, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Canada
| | - Taehoon Bok
- Department of Physics, Toronto Metropolitan University (Formerly Ryerson University), Toronto, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael’s Hospital, Toronto, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Canada
| | - Omar Nusrat
- Department of Physics, Toronto Metropolitan University (Formerly Ryerson University), Toronto, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael’s Hospital, Toronto, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Canada
| | - Michael C. Kolios
- Department of Physics, Toronto Metropolitan University (Formerly Ryerson University), Toronto, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael’s Hospital, Toronto, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Canada
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Aerosolize this: Generation, collection, and analysis of aerosolized virus in laboratory settings. PLoS Pathog 2023; 19:e1011178. [PMID: 36893118 PMCID: PMC9997909 DOI: 10.1371/journal.ppat.1011178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/10/2023] Open
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10
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Photoactive decontamination and reuse of face masks. E-PRIME - ADVANCES IN ELECTRICAL ENGINEERING, ELECTRONICS AND ENERGY 2023:100129. [PMCID: PMC9942455 DOI: 10.1016/j.prime.2023.100129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The corona virus disease 2019 (COVID-19) pandemic has led to global shortages in disposable respirators. Increasing the recycling rate of masks is a direct, low-cost strategy to mitigate COVID-19 transmission. Photoactive decontamination of used masks attracts great attention due to its fast response, remarkable virus inactivation effect and full protection integrity. Here, we review state-of-the-art situation of photoactive decontamination. The basic mechanism of photoactive decontamination is firstly discussed in terms of ultraviolet, photothermal or photocatalytic properties. Among which, ultraviolet radiation damages DNA and RNA to inactivate viruses and microorganisms, and photothermal method damages them by destroying proteins, while photocatalysis kills them by destroying the structure. The practical applications of photoactive decontamination strategies are then fully reviewed, including ultraviolet germicidal irradiation, and unconventional masks made of functional nanomaterials with photothermal or photocatalytic properties. Their performance requirements are elaborated together with the advantages of long-term recycle use. Finally, we put forward challenges and prospects for further development of photoactive decontamination technology.
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Ye X, Wang Y, Zou Y, Tu J, Tang W, Yu R, Yang S, Huang P. Associations of socioeconomic status with infectious diseases mediated by lifestyle, environmental pollution and chronic comorbidities: a comprehensive evaluation based on UK Biobank. Infect Dis Poverty 2023; 12:5. [PMID: 36717939 PMCID: PMC9885698 DOI: 10.1186/s40249-023-01056-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 01/16/2023] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Socioeconomic status (SES) inequity was recognized as a driver of some certain infectious diseases. However, few studies evaluated the association between SES and the burden of overall infections, and even fewer identified preventable mediators. This study aimed to assess the association between SES and overall infectious diseases burden, and the potential roles of factors including lifestyle, environmental pollution, chronic disease history. METHODS We included 401,009 participants from the UK Biobank (UKB) and defined the infection status for each participant according to their diagnosis records. Latent class analysis (LCA) was used to define SES for each participant. We further defined healthy lifestyle score, environment pollution score (EPS) and four types of chronic comorbidities. We used multivariate logistic regression to test the associations between the four above covariates and infectious diseases. Then, we performed the mediation and interaction analysis to explain the relationships between SES and other variables on infectious diseases. Finally, we employed seven types of sensitivity analyses, including considering the Townsend deprivation index as an area level SES variable, repeating our main analysis for some individual or composite factors and in some subgroups, as well as in an external data from the US National Health and Nutrition Examination Survey, to verify the main results. RESULTS In UKB, 60,771 (15.2%) participants were diagnosed with infectious diseases during follow-up. Lower SES [odds ratio (OR) = 1.5570] were associated with higher risk of overall infections. Lifestyle score mediated 2.9% of effects from SES, which ranged from 2.9 to 4.0% in different infection subtypes, while cardiovascular disease (CVD) mediated a proportion of 6.2% with a range from 2.1 to 6.8%. In addition, SES showed significant negative interaction with lifestyle score (OR = 0.8650) and a history of cancer (OR = 0.9096), while a significant synergy interaction was observed between SES and EPS (OR = 1.0024). In subgroup analysis, we found that males and African (AFR) with lower SES showed much higher infection risk. Results from sensitivity and validation analyses showed relative consistent with the main analysis. CONCLUSIONS Low SES is shown to be an important risk factor for infectious disease, part of which may be mediated by poor lifestyle and chronic comorbidities. Efforts to enhance health education and improve the quality of living environment may help reduce burden of infectious disease, especially for people with low SES.
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Affiliation(s)
- Xiangyu Ye
- grid.89957.3a0000 0000 9255 8984Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Yidi Wang
- grid.89957.3a0000 0000 9255 8984Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Yixin Zou
- grid.89957.3a0000 0000 9255 8984Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Junlan Tu
- grid.89957.3a0000 0000 9255 8984Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Weiming Tang
- grid.89957.3a0000 0000 9255 8984Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China ,grid.410711.20000 0001 1034 1720Institute of Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, CA USA
| | - Rongbin Yu
- grid.89957.3a0000 0000 9255 8984Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Sheng Yang
- grid.89957.3a0000 0000 9255 8984Department of Biostatistics, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Peng Huang
- grid.89957.3a0000 0000 9255 8984Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
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12
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Verheyen CA, Bourouiba L. Associations between indoor relative humidity and global COVID-19 outcomes. J R Soc Interface 2022; 19:20210865. [PMID: 36382379 PMCID: PMC9667146 DOI: 10.1098/rsif.2021.0865] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 10/27/2022] [Indexed: 09/29/2023] Open
Abstract
Globally, the spread and severity of COVID-19 have been distinctly non-uniform. Seasonality was suggested as a contributor to regional variability, but the relationship between weather and COVID-19 remains unclear and the focus of attention has been on outdoor conditions. Because humans spend most of their time indoors and because most transmission occurs indoors, we here, instead, investigate the hypothesis that indoor climate-particularly indoor relative humidity (RH)-may be the more relevant modulator of outbreaks. To study this association, we combined population-based COVID-19 statistics and meteorological measurements from 121 countries. We rigorously processed epidemiological data to reduce bias, then developed and experimentally validated a computational workflow to estimate indoor conditions based on outdoor weather data and standard indoor comfort conditions. Our comprehensive analysis shows robust and systematic relationships between regional outbreaks and indoor RH. In particular, we found intermediate RH (40-60%) to be robustly associated with better COVID-19 outbreak outcomes (versus RH < 40% or >60%). Together, these results suggest that indoor conditions, particularly indoor RH, modulate the spread and severity of COVID-19 outbreaks.
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Affiliation(s)
- C. A. Verheyen
- Harvard-MIT Health Sciences and Technology, Boston, MA, USA
- Institute for Medical Engineering and Science, MIT, Cambridge, MA, USA
| | - L. Bourouiba
- Harvard-MIT Health Sciences and Technology, Boston, MA, USA
- Institute for Medical Engineering and Science, MIT, Cambridge, MA, USA
- The Fluid Dynamics of Disease Transmission Laboratory, MIT, Cambridge, MA, USA
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13
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Geng Y, Wang Y. Stability and transmissibility of SARS-CoV-2 in the environment. J Med Virol 2022; 95:e28103. [PMID: 36039831 PMCID: PMC9537778 DOI: 10.1002/jmv.28103] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 01/11/2023]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing the ongoing global coronavirus disease 2019 (COVID-19) pandemic, is believed to be transmitted primarily through respiratory droplets and aerosols. However, reports are increasing regarding the contamination of environmental surfaces, shared objects, and cold-chain foods with SARS-CoV-2 RNA and the possibility of environmental fomite transmission of the virus raises much concern and debate. This study summarizes the current knowledge regarding potential mechanisms of environmental transmission of SARS-CoV-2, including the prevalence of surface contamination in various settings, the viability and stability of the virus on surfaces or fomites, as well as environmental factors affecting virus viability and survival such as temperature and relative humidity. Instances of fomite transmission, including cold-chain food transmission, and the importance of fomite transmission in epidemics, are discussed. The knowledge gaps regarding fomite transmission of SARS-CoV-2 are also briefly analyzed.
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Affiliation(s)
- Yansheng Geng
- Key Laboratory of Public Health Safety of Hebei Province, School of Public HealthHebei UniversityBaodingChina
| | - Youchun Wang
- Division of HIV/AIDS and Sex‐Transmitted Virus VaccinesNational Institutes for Food and Drug ControlBeijingChina
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14
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Lee H, Lee YK, Park JY, Han JW. Analysis of flow rate and pressure in syringe-based wound irrigation using Bernoulli's equation. Sci Rep 2022; 12:14957. [PMID: 36056149 PMCID: PMC9440234 DOI: 10.1038/s41598-022-19402-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
The objective of this study was to examine the dependence of the pressure level in the wound area on the height of the syringe needle from the wound, the gauge of the needle, and the flow rate using the Bernoulli equation. This study was the control-volume analysis using the Bernoulli equation. At a given height of the syringe needle from the wound, the gauge of the syringe needle was fixed, and the pressure in the wound area, which depended on the flow rate of the irrigation solution discharged from the tip of the needle, was calculated according to the Bernoulli equation and the definition of the flow rate. At a constant flow rate of the irrigation solution, the velocity of the irrigation solution discharged through the syringe needle decreased (7.80 → 0.80) with an increase in the diameter of the needle (18G → 14G). At a constant inner diameter of the needle, the velocity of the irrigation solution increased with a reduction in the flow rate of the solution. As the velocity of the irrigation solution increased, the pressure in the wound area increased. As the height of the syringe needle from the wound area increased, the pressure in the wound area increased. In order to maintain the pressure of 8-15 psi when nurses perform syringe-based irrigation, it is necessary to set the flow rate of the cleaning solution from 3.5 cc/s to less than 4.8 cc/s for 19G. In addition, 20G maintains the flow rate of the solution at 2.6 cc/s or more and less than 3.5 cc/s, 22G maintains the flow rate of solution at 1.3 cc/s or more and less than 1.8 cc/s, and 25G maintains the flow rate of solution at 0.5 cc/s. This study provides nurses with a reference for the flow rate at which syringe-based irrigation can be performed while maintaining the appropriate pressure based on fluid dynamics, which can be used as the basis for wound nursing standards.
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Affiliation(s)
- Hanna Lee
- Gangneung-Wonju National University, Wonju-si, Gangwon-do, Republic of Korea
| | - Ye-Kyung Lee
- College of Nursing Science, Kyung Hee University, Seoul, Republic of Korea
| | - Ji-Yun Park
- College of Nursing Science, Kyung Hee University, Seoul, Republic of Korea
| | - Jeong-Won Han
- College of Nursing Science, Kyung Hee University, Seoul, Republic of Korea.
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15
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French AJ, Longest AK, Pan J, Vikesland PJ, Duggal NK, Lakdawala SS, Marr LC. Environmental Stability of Enveloped Viruses is Impacted by the Initial Volume and Evaporation Kinetics of Droplets.. [PMID: 35923308 PMCID: PMC9347275 DOI: 10.1101/2022.07.26.501658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractEfficient spread of respiratory viruses requires the virus to maintain infectivity in the environment. Environmental stability of viruses can be influenced by many factors, including temperature and humidity. Our study measured the impact of initial droplet volume (50, 5, and 1 µL) and relative humidity (RH: 40%, 65%, and 85%) on the stability of influenza A virus, bacteriophage, Phi6, a common surrogate for enveloped viruses, and SARS-CoV-2 under a limited set of conditions. Our data suggest that the drying time required for the droplets to reach quasi-equilibrium (i.e. a plateau in mass) varied with RH and initial droplet volume. The macroscale physical characteristics of the droplets at quasi-equilibrium varied with RH but not with initial droplet volume. We observed more rapid virus decay when the droplets were still wet and undergoing evaporation, and slower decay after the droplets had dried. Initial droplet volume had a major effect on virus viability over the first few hours; whereby the decay rate of influenza virus was faster in smaller droplets. In general, influenza virus and SARS-CoV-2 decayed similarly. Overall, this study suggests that virus decay in media is closely correlated with the extent of droplet evaporation, which is controlled by RH. Taken together, these data suggest that decay of different viruses is more similar at higher RH and in smaller droplets and is distinct at lower RH and in larger droplets. Importantly, accurate assessment of transmission risk requires use of physiologically relevant droplet volumes and careful consideration of the use of surrogates.FundingNational Institute of Allergy and Infectious Diseases, National Institute of Neurological Disorders and Stroke, National Institutes of Health; Department of Health and Human Services; Flu Lab.ImportanceDuring the COVID-19 pandemic, policy decisions were being driven by virus stability experiments involving SARS-CoV-2 applied to surfaces in large droplets at various humidity conditions. The results of our study indicate that determination of half-lives for emerging pathogens in large droplets likely over-estimates transmission risk for contaminated surfaces, as occurred during the COVID-19 pandemic. Our study implicates the need for the use of physiologically relevant droplet sizes with use of relevant surrogates in addition to what is already known about the importance of physiologically relevant media for risk assessment of future emerging pathogens.
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16
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Chen A, Wessler T, Daftari K, Hinton K, Boucher RC, Pickles R, Freeman R, Lai SK, Forest MG. Modeling insights into SARS-CoV-2 respiratory tract infections prior to immune protection. Biophys J 2022; 121:1619-1631. [PMID: 35378080 PMCID: PMC8975607 DOI: 10.1016/j.bpj.2022.04.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/27/2021] [Accepted: 03/31/2022] [Indexed: 11/19/2022] Open
Abstract
Mechanistic insights into human respiratory tract (RT) infections from SARS-CoV-2 can inform public awareness as well as guide medical prevention and treatment for COVID-19 disease. Yet the complexity of the RT and the inability to access diverse regions pose fundamental roadblocks to evaluation of potential mechanisms for the onset and progression of infection (and transmission). We present a model that incorporates detailed RT anatomy and physiology, including airway geometry, physical dimensions, thicknesses of airway surface liquids (ASLs), and mucus layer transport by cilia. The model further incorporates SARS-CoV-2 diffusivity in ASLs and best-known data for epithelial cell infection probabilities, and, once infected, duration of eclipse and replication phases, and replication rate of infectious virions. We apply this baseline model in the absence of immune protection to explore immediate, short-term outcomes from novel SARS-CoV-2 depositions onto the air-ASL interface. For each RT location, we compute probability to clear versus infect; per infected cell, we compute dynamics of viral load and cell infection. Results reveal that nasal infections are highly likely within 1-2 days from minimal exposure, and alveolar pneumonia occurs only if infectious virions are deposited directly into alveolar ducts and sacs, not via retrograde propagation to the deep lung. Furthermore, to infect just 1% of the 140 m2 of alveolar surface area within 1 week, either 103 boluses each with 106 infectious virions or 106 aerosols with one infectious virion, all physically separated, must be directly deposited. These results strongly suggest that COVID-19 disease occurs in stages: a nasal/upper RT infection, followed by self-transmission of infection to the deep lung. Two mechanisms of self-transmission are persistent aspiration of infected nasal boluses that drain to the deep lung and repeated rupture of nasal aerosols from infected mucosal membranes by speaking, singing, or cheering that are partially inhaled, exhaled, and re-inhaled, to the deep lung.
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Affiliation(s)
- Alexander Chen
- Department of Mathematics, CSU Dominguez Hills, Carson, California
| | - Timothy Wessler
- Department of Mathematics, UNC Chapel Hill, Chapel Hill, North Carolina.
| | - Katherine Daftari
- Department of Mathematics, UNC Chapel Hill, Chapel Hill, North Carolina
| | - Kameryn Hinton
- Department of Applied Physical Sciences, UNC Chapel Hill, Chapel Hill, North Carolina
| | - Richard C Boucher
- Marsico Lung Institute, UNC Chapel Hill, Chapel Hill, North Carolina
| | - Raymond Pickles
- Marsico Lung Institute, UNC Chapel Hill, Chapel Hill, North Carolina; Department of Microbiology and Immunology, UNC Chapel Hill, Chapel Hill, North Carolina
| | - Ronit Freeman
- Department of Applied Physical Sciences, UNC Chapel Hill, Chapel Hill, North Carolina
| | - Samuel K Lai
- Department of Microbiology and Immunology, UNC Chapel Hill, Chapel Hill, North Carolina; Joint Department of Biomedical Engineering, UNC Chapel Hill and NC State University, Chapel Hill and Raleigh, North Carolina; Division of Pharmacoengineering and Molecular Pharmaceutics, Eshelman School of Pharmacy, UNC Chapel Hill, Chapel Hill, North Carolina
| | - M Gregory Forest
- Department of Mathematics, UNC Chapel Hill, Chapel Hill, North Carolina; Department of Applied Physical Sciences, UNC Chapel Hill, Chapel Hill, North Carolina; Joint Department of Biomedical Engineering, UNC Chapel Hill and NC State University, Chapel Hill and Raleigh, North Carolina.
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17
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Stettler MEJ, Nishida RT, de Oliveira PM, Mesquita LCC, Johnson TJ, Galea ER, Grandison A, Ewer J, Carruthers D, Sykes D, Kumar P, Avital E, Obeysekara AIB, Doorly D, Hardalupas Y, Green DC, Coldrick S, Parker S, Boies AM. Source terms for benchmarking models of SARS-CoV-2 transmission via aerosols and droplets. ROYAL SOCIETY OPEN SCIENCE 2022. [PMID: 35592762 DOI: 10.6084/m9.figshare.c.5958950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
There is ongoing and rapid advancement in approaches to modelling the fate of exhaled particles in different environments relevant to disease transmission. It is important that models are verified by comparison with each other using a common set of input parameters to ensure that model differences can be interpreted in terms of model physics rather than unspecified differences in model input parameters. In this paper, we define parameters necessary for such benchmarking of models of airborne particles exhaled by humans and transported in the environment during breathing and speaking.
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Affiliation(s)
- Marc E J Stettler
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK
| | - Robert T Nishida
- Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G8
| | | | - Léo C C Mesquita
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
| | - Tyler J Johnson
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
| | - Edwin R Galea
- Fire Safety Engineering Group, University of Greenwich, London SE10 9LS, UK
| | - Angus Grandison
- Fire Safety Engineering Group, University of Greenwich, London SE10 9LS, UK
| | - John Ewer
- Fire Safety Engineering Group, University of Greenwich, London SE10 9LS, UK
| | - David Carruthers
- Cambridge Environmental Research Consultants Ltd, 3 Kings Parade, Cambridge CB2 1SJ, UK
| | | | - Prashant Kumar
- Global Centre for Clean Air Research (GCARE), Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Eldad Avital
- School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
| | - Asiri I B Obeysekara
- Applied Modelling and Computation Group, Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK
| | - Denis Doorly
- Department of Aeronautics, Imperial College London, London SW7 2AZ, UK
| | - Yannis Hardalupas
- Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK
| | - David C Green
- MRC Centre for Environment and Health, Environmental Research Group, Imperial College London, Michael Uren Biomedical Engineering Hub, London, W12 OBZ, UK
- NIHR HPRU in Environmental Exposures and Health, Imperial College London, Michael Uren Biomedical Engineering Hub, London, W12 OBZ, UK
| | - Simon Coldrick
- Health and Safety Executive, Harpur Hill, Buxton, Derbyshire SK17 9JN UK
| | - Simon Parker
- Defence Science and Technology Laboratory, Porton Down, Salisbury SP4 0JQ, UK
| | - Adam M Boies
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
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18
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Stettler MEJ, Nishida RT, de Oliveira PM, Mesquita LCC, Johnson TJ, Galea ER, Grandison A, Ewer J, Carruthers D, Sykes D, Kumar P, Avital E, Obeysekara AIB, Doorly D, Hardalupas Y, Green DC, Coldrick S, Parker S, Boies AM. Source terms for benchmarking models of SARS-CoV-2 transmission via aerosols and droplets. ROYAL SOCIETY OPEN SCIENCE 2022; 9:212022. [PMID: 35592762 PMCID: PMC9066307 DOI: 10.1098/rsos.212022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/13/2022] [Indexed: 05/03/2023]
Abstract
There is ongoing and rapid advancement in approaches to modelling the fate of exhaled particles in different environments relevant to disease transmission. It is important that models are verified by comparison with each other using a common set of input parameters to ensure that model differences can be interpreted in terms of model physics rather than unspecified differences in model input parameters. In this paper, we define parameters necessary for such benchmarking of models of airborne particles exhaled by humans and transported in the environment during breathing and speaking.
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Affiliation(s)
- Marc E. J. Stettler
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK
| | - Robert T. Nishida
- Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G8
| | | | - Léo C. C. Mesquita
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
| | - Tyler J. Johnson
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
| | - Edwin R. Galea
- Fire Safety Engineering Group, University of Greenwich, London SE10 9LS, UK
| | - Angus Grandison
- Fire Safety Engineering Group, University of Greenwich, London SE10 9LS, UK
| | - John Ewer
- Fire Safety Engineering Group, University of Greenwich, London SE10 9LS, UK
| | - David Carruthers
- Cambridge Environmental Research Consultants Ltd, 3 Kings Parade, Cambridge CB2 1SJ, UK
| | | | - Prashant Kumar
- Global Centre for Clean Air Research (GCARE), Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Eldad Avital
- School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
| | - Asiri I. B. Obeysekara
- Applied Modelling and Computation Group, Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK
| | - Denis Doorly
- Department of Aeronautics, Imperial College London, London SW7 2AZ, UK
| | - Yannis Hardalupas
- Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK
| | - David C. Green
- MRC Centre for Environment and Health, Environmental Research Group, Imperial College London, Michael Uren Biomedical Engineering Hub, London, W12 OBZ, UK
- NIHR HPRU in Environmental Exposures and Health, Imperial College London, Michael Uren Biomedical Engineering Hub, London, W12 OBZ, UK
| | - Simon Coldrick
- Health and Safety Executive, Harpur Hill, Buxton, Derbyshire SK17 9JN UK
| | - Simon Parker
- Defence Science and Technology Laboratory, Porton Down, Salisbury SP4 0JQ, UK
| | - Adam M. Boies
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
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19
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Rodríguez-Hakim M, Räz L, Vermant J. Variations in human saliva viscoelasticity affect aerosolization propensity. SOFT MATTER 2022; 18:2528-2540. [PMID: 35113119 DOI: 10.1039/d1sm01581h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Some contagious diseases, such as COVID-19, spread through the transmission of aerosols and droplets. Aerosol and droplet formation occurs inside and outside of the respiratory tract, the latter being observed during speaking and sneezing. Upon sneezing, saliva is expelled as a flat sheet, which destabilizes into filaments that subsequently break up into droplets. The presence of macromolecules (such as mucins) in saliva influences the dynamics of aerosol generation, since elasticity is expected to stabilize both fluid sheets and filaments, hence deterring droplet formation. In this study, the process of aerosol formation outside the respiratory tract is systematically replicated using an impinging jet setup, where two liquid jets collide and form a thin fluid sheet that can fragment into ligaments and droplets. The experimental setup enables us to investigate a range of dynamic conditions, quantified by the relevant non-dimensional numbers, which encompass those experienced during sneezing. Experiments are conducted with human saliva provided by different donors, revealing significant variations in their stability and breakup. We quantify the effect of viscoelasticity via shear and extensional rheology experiments, concluding that the extensional relaxation time is the most adequate measure of a saliva's elasticity. We summarize our results in terms of the dimensionless Weber, Reynolds, and Deborah numbers and construct universal state diagrams that directly compare our data to human sneezing, concluding that the aerosolization propensity is correlated with diminished saliva elasticities, higher emission velocities, and larger ejecta volumes. This could entail variations in disease transmission between individuals which hitherto have not been recognized.
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Affiliation(s)
| | - Linard Räz
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, Zürich, 8093, Switzerland.
| | - Jan Vermant
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, Zürich, 8093, Switzerland.
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20
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Henriques A, Mounet N, Aleixo L, Elson P, Devine J, Azzopardi G, Andreini M, Rognlien M, Tarocco N, Tang J. Modelling airborne transmission of SARS-CoV-2 using CARA: risk assessment for enclosed spaces. Interface Focus 2022; 12:20210076. [PMID: 35261732 PMCID: PMC8831086 DOI: 10.1098/rsfs.2021.0076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 12/19/2021] [Indexed: 12/18/2022] Open
Abstract
The COVID-19 pandemic has highlighted the need for a proper risk assessment of respiratory pathogens in indoor settings. This paper documents the COVID Airborne Risk Assessment methodology, to assess the potential exposure of airborne SARS-CoV-2 viruses, with an emphasis on virological and immunological factors in the quantification of the risk. The model results from a multidisciplinary approach linking physical, mechanical and biological domains, enabling decision makers or facility managers to assess their indoor setting. The model was benchmarked against clinical data, as well as two real-life outbreaks, showing good agreement. A probability of infection is computed in several everyday-life settings and with various mitigation measures. The importance of super-emitters in airborne transmission is confirmed: 20% of infected hosts can emit approximately two orders of magnitude more viral-containing particles. The use of masks provides a fivefold reduction in viral emissions. Natural ventilation strategies are very effective to decrease the concentration of virions, although periodic venting strategies are not ideal in certain settings. Although vaccination is an effective measure against hospitalization, their effectiveness against transmission is not optimal, hence non-pharmaceutical interventions (ventilation, masks) should be actively supported. We also propose a critical threshold to define an acceptable risk level.
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Affiliation(s)
- Andre Henriques
- CERN (European Organization for Nuclear Research), Geneva, Switzerland
| | - Nicolas Mounet
- CERN (European Organization for Nuclear Research), Geneva, Switzerland
| | - Luis Aleixo
- CERN (European Organization for Nuclear Research), Geneva, Switzerland
| | - Philip Elson
- CERN (European Organization for Nuclear Research), Geneva, Switzerland
| | - James Devine
- CERN (European Organization for Nuclear Research), Geneva, Switzerland
| | | | - Marco Andreini
- CERN (European Organization for Nuclear Research), Geneva, Switzerland
| | - Markus Rognlien
- NTNU (Norwegian University of Science and Technology), Torgarden, Norway
| | - Nicola Tarocco
- CERN (European Organization for Nuclear Research), Geneva, Switzerland
| | - Julian Tang
- Respiratory Sciences, University of Leicester, Leicester, UK
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21
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Coyle JP, Derk RC, Lindsley WG, Boots T, Blachere FM, Reynolds JS, McKinney WG, Sinsel EW, Lemons AR, Beezhold DH, Noti JD. Reduction of exposure to simulated respiratory aerosols using ventilation, physical distancing, and universal masking. INDOOR AIR 2022; 32:e12987. [PMID: 35225389 PMCID: PMC8988470 DOI: 10.1111/ina.12987] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 12/23/2021] [Accepted: 12/24/2021] [Indexed: 06/14/2023]
Abstract
To limit community spread of SARS-CoV-2, CDC recommends universal masking indoors, maintaining 1.8 m of physical distancing, adequate ventilation, and avoiding crowded indoor spaces. Several studies have examined the independent influence of each control strategy in mitigating transmission in isolation, yet controls are often implemented concomitantly within an indoor environment. To address the influence of physical distancing, universal masking, and ventilation on very fine respiratory droplets and aerosol particle exposure, a simulator that coughed and exhaled aerosols (the source) and a second breathing simulator (the recipient) were placed in an exposure chamber. When controlling for the other two mitigation strategies, universal masking with 3-ply cotton masks reduced exposure to 0.3-3 µm coughed and exhaled aerosol particles by >77% compared to unmasked tests, whereas physical distancing (0.9 or 1.8 m) significantly changed exposure to cough but not exhaled aerosols. The effectiveness of ventilation depended upon the respiratory activity, that is, coughing or breathing, as well as the duration of exposure time. Our results demonstrate that a layered mitigation strategy approach of administrative and engineering controls can reduce personal inhalation exposure to potentially infectious very fine respiratory droplets and aerosol particles within an indoor environment.
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Affiliation(s)
- Jayme P. Coyle
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - Raymond C. Derk
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - William G. Lindsley
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - Theresa Boots
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - Francoise M. Blachere
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - Jeffrey S. Reynolds
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - Walter G. McKinney
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - Erik W. Sinsel
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - Angela R. Lemons
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - Donald H. Beezhold
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - John D. Noti
- Health Effects Laboratory DivisionCenters for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
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22
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Greenhalgh T, Peng Z, Jimenez JL, Bahnfleth W, Dancer SJ, Bourouiba L. Quantifying transmission risk of SARS-CoV-2 in different situations. BMJ 2022; 376:o106. [PMID: 35058231 DOI: 10.1136/bmj.o106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- T Greenhalgh
- Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK
| | - Zhe Peng
- Department of Chemistry and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Jose L Jimenez
- Department of Chemistry and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - W Bahnfleth
- Department of Architectural Engineering, Pennsylvania State University, University Park, PA 16802, USA
| | - S J Dancer
- Department of Microbiology, NHS Lanarkshire, Glasgow, UK
- School of Applied Sciences, Edinburgh Napier University, Edinburgh, UK
| | - L Bourouiba
- Fluid Dynamics of Disease Transmission Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
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23
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Inherent heterogeneity of influenza A virus stability following aerosolization. Appl Environ Microbiol 2022; 88:e0227121. [PMID: 34985975 DOI: 10.1128/aem.02271-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Efficient human-to-human transmission represents a necessary adaptation for a zoonotic influenza A virus (IAV) to cause a pandemic. As such, many emerging IAVs are characterized for transmissibility phenotypes in mammalian models, with an emphasis on elucidating viral determinants of transmission and the role host immune responses contribute to mammalian adaptation. Investigations of virus infectivity and stability in aerosols concurrent with transmission assessments have increased in recent years, enhancing our understanding of this dynamic process. Here, we employ a diverse panel of 17 human and zoonotic IAVs, inclusive of seasonally circulating H1N1 and H3N2 viruses, and avian and swine viruses associated with human infection, to evaluate differences in spray factor (a value that assesses efficiency of the aerosolization process), stability, and infectivity following aerosolization. While most seasonal influenza viruses did not exhibit substantial variability within these parameters, there was more heterogeneity among zoonotic influenza viruses, which possess a diverse range of transmission phenotypes. Aging of aerosols at different relative humidities identified strain-specific levels of stability with different profiles identified between zoonotic H3, H5, and H7 subtype viruses associated with human infection. As studies continue to elucidate the complex components governing virus transmissibility, notably aerosol matrices and environmental parameters, considering the relative role of subtype- and strain-specific factors to modulate these parameters will improve our understanding of the pandemic potential of zoonotic influenza A viruses. Importance Transmission of respiratory pathogens through the air can facilitate the rapid and expansive spread of infection and disease through a susceptible population. While seasonal influenza viruses are quite capable of airborne spread, there is a lack of knowledge regarding how well influenza viruses remain viable after aerosolization, and if influenza viruses capable of jumping species barriers to cause human infection differ in this property from seasonal strains. We evaluated a diverse panel of influenza viruses associated with human infection (originating from human, avian, and swine reservoirs) for their ability to remain viable after aerosolization in the laboratory under a range of conditions. We found greater diversity among avian and swine-origin viruses compared with seasonal influenza viruses; strain-specific stability was also noted. Although influenza virus stability in aerosols is an underreported property, if molecular markers associated with enhanced stability are identified, we will be able to quickly recognize emerging strains of influenza that present the greatest pandemic threat.
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24
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Krishnan RG, Cenci S, Bourouiba L. Mitigating bias in estimating epidemic severity due to heterogeneity of epidemic onset and data aggregation. Ann Epidemiol 2022; 65:1-14. [PMID: 34419601 PMCID: PMC8375253 DOI: 10.1016/j.annepidem.2021.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 06/11/2021] [Accepted: 07/18/2021] [Indexed: 11/16/2022]
Abstract
Outbreaks of infectious diseases, such as influenza, are a major societal burden. Mitigation policies during an outbreak or pandemic are guided by the analysis of data of ongoing or preceding epidemics. The reproduction number, R0, defined as the expected number of secondary infections arising from a single individual in a population of susceptibles is critical to epidemiology. For typical compartmental models such as the Susceptible-Infected-Recovered (SIR) R0 represents the severity of an epidemic. It is an estimate of the early-stage growth rate of an epidemic and is an important threshold parameter used to gain insights into the spread or decay of an outbreak. Models typically use incidence counts as indicators of cases within a single large population; however, epidemic data are the result of a hierarchical aggregation, where incidence counts from spatially separated monitoring sites (or sub-regions) are pooled and used to infer R0. Is this aggregation approach valid when the epidemic has different dynamics across the regions monitored? We characterize bias in the estimation of R0 from a merged data set when the epidemics of the sub-regions, used in the merger, exhibit delays in onset. We propose a method to mitigate this bias, and study its efficacy on synthetic data as well as real-world influenza and COVID-19 data.
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Affiliation(s)
- R G Krishnan
- Massachusetts Institute of Technology, Cambridge, MA
| | - S Cenci
- Massachusetts Institute of Technology, Cambridge, MA; Imperial College London, UK
| | - L Bourouiba
- Massachusetts Institute of Technology, Cambridge, MA; Health Sciences & Technology Program, Harvard Medical School, Boston, MA.
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Biswas R, Pal A, Pal R, Sarkar S, Mukhopadhyay A. Risk assessment of COVID infection by respiratory droplets from cough for various ventilation scenarios inside an elevator: An OpenFOAM-based computational fluid dynamics analysis. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2022; 34:013318. [PMID: 35340680 PMCID: PMC8939552 DOI: 10.1063/5.0073694] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 12/30/2021] [Indexed: 05/15/2023]
Abstract
Respiratory droplets-which may contain disease spreading virus-exhaled during speaking, coughing, or sneezing are one of the significant causes for the spread of the ongoing COVID-19 pandemic. The droplet dispersion depends on the surrounding air velocity, ambient temperature, and relative humidity. In a confined space like an elevator, the risk of transmission becomes higher when there is an infected person inside the elevator with other individuals. In this work, a numerical investigation is carried out in a three-dimensional domain resembling an elevator using OpenFoam. Three different modes of air ventilation, viz., quiescent, axial exhaust draft, and exhaust fan, have been considered to investigate the effect of ventilation on droplet transmission for two different climatic conditions (30 °C , 50% relative humidity and 10 °C , 90% relative humidity). The risk assessment is quantified using a risk factor based on the time-averaged droplet count present near the passenger's hand to head region (risky height zone). The risk factor drops from 40% in a quiescent scenario to 0% in an exhaust fan ventilation condition in a hot dry environment. In general, cold humid conditions are safer than hot dry conditions as the droplets settle down quickly below the risky height zone owing to their larger masses maintained by negligible evaporation. However, an exhaust fan renders the domain in a hot dry ambience completely safe (risk factor, 0%) in 5.5 s whereas it takes 7.48 s for a cold humid ambience.
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Affiliation(s)
- Riddhideep Biswas
- Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, India
| | - Anish Pal
- Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, India
| | - Ritam Pal
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Sourav Sarkar
- Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, India
- Author to whom correspondence should be addressed:
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Bueno de Mesquita PJ, Delp WW, Chan WR, Bahnfleth WP, Singer BC. Control of airborne infectious disease in buildings: Evidence and research priorities. INDOOR AIR 2022; 32:e12965. [PMID: 34816493 DOI: 10.1111/ina.12965] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 10/07/2021] [Accepted: 11/11/2021] [Indexed: 06/13/2023]
Abstract
The evolution of SARS-CoV-2 virus has resulted in variants likely to be more readily transmitted through respiratory aerosols, underscoring the increased potential for indoor environmental controls to mitigate risk. Use of tight-fitting face masks to trap infectious aerosol in exhaled breath and reduce inhalation exposure to contaminated air is of critical importance for disease control. Administrative controls including the regulation of occupancy and interpersonal spacing are also important, while presenting social and economic challenges. Indoor engineering controls including ventilation, exhaust, air flow control, filtration, and disinfection by germicidal ultraviolet irradiation can reduce reliance on stringent occupancy restrictions. However, the effects of controls-individually and in combination-on reducing infectious aerosol transfer indoors remain to be clearly characterized to the extent needed to support widespread implementation by building operators. We review aerobiologic and epidemiologic evidence of indoor environmental controls against transmission and present a quantitative aerosol transfer scenario illustrating relative differences in exposure at close-interactive, room, and building scales. We identify an overarching need for investment to implement building controls and evaluate their effectiveness on infection in well-characterized and real-world settings, supported by specific, methodological advances. Improved understanding of engineering control effectiveness guides implementation at scale while considering occupant comfort, operational challenges, and energy costs.
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Affiliation(s)
| | - William W Delp
- Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Wanyu R Chan
- Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - William P Bahnfleth
- Department of Architectural Engineering, Pennsylvania State University, State College, Pennsylvania, USA
| | - Brett C Singer
- Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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Randall K, Ewing ET, Marr LC, Jimenez JL, Bourouiba L. How did we get here: what are droplets and aerosols and how far do they go? A historical perspective on the transmission of respiratory infectious diseases. Interface Focus 2021; 11:20210049. [PMID: 34956601 PMCID: PMC8504878 DOI: 10.1098/rsfs.2021.0049] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2021] [Indexed: 12/19/2022] Open
Abstract
The COVID-19 pandemic has exposed major gaps in our understanding of the transmission of viruses through the air. These gaps slowed recognition of airborne transmission of the disease, contributed to muddled public health policies and impeded clear messaging on how best to slow transmission of COVID-19. In particular, current recommendations have been based on four tenets: (i) respiratory disease transmission routes can be viewed mostly in a binary manner of ‘droplets’ versus ‘aerosols’; (ii) this dichotomy depends on droplet size alone; (iii) the cut-off size between these routes of transmission is 5 µm; and (iv) there is a dichotomy in the distance at which transmission by each route is relevant. Yet, a relationship between these assertions is not supported by current scientific knowledge. Here, we revisit the historical foundation of these notions, and how they became entangled from the 1800s to today, with a complex interplay among various fields of science and medicine. This journey into the past highlights potential solutions for better collaboration and integration of scientific results into practice for building a more resilient society with more sound, far-sighted and effective public health policies.
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Affiliation(s)
- K Randall
- Department of Civil & Environmental Engineering, Virginia Tech, Blacksburg, VA, USA
| | - E T Ewing
- Department of Civil & Environmental Engineering, Virginia Tech, Blacksburg, VA, USA
| | - L C Marr
- Department of Civil & Environmental Engineering, Virginia Tech, Blacksburg, VA, USA
| | - J L Jimenez
- Department of Chemistry and CIRES, University of Colorado, Boulder, CO, USA
| | - L Bourouiba
- Fluid Dynamics of Disease Transmission Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
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Marr LC, Tang JW. A Paradigm Shift to Align Transmission Routes With Mechanisms. Clin Infect Dis 2021; 73:1747-1749. [PMID: 34415335 DOI: 10.1093/cid/ciab722] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Indexed: 11/14/2022] Open
Abstract
Current infection-control guidelines subscribe to a contact/droplet/airborne paradigm that is based on outdated understanding. Here, we propose to modify and align existing guidelines with a more accurate description of the different transmission routes. This will improve the effectiveness of control measures as more transmissible variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerge.
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Affiliation(s)
- Linsey C Marr
- Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, USA
| | - Julian W Tang
- Respiratory Sciences, University of Leicester, Leicester, United Kingdom
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SARS-COV2 Statistical Analysis–Constanta Family Medicine Cabinet in the Period 2020–2022. ARS MEDICA TOMITANA 2021. [DOI: 10.2478/arsm-2021-0028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Abstract
SARS-COV2 translates as a highlycontagious viral strain, being part of thegenusBetacoronavirus, the Sarbecovirus subgroup, consisting of a single molecule of single-stranded RNA, withpositivepolarityandhavingdimensions of 27-32 kb.
The timefromthetransposition of infectiontotheonset of symptomatology in order of frequency:cough,dysphagia, fever,breathlessness, anosmia, ageusia, headacheandfatiguabilityisbetween2-12days, with an average of 6days.
The purpose of thisstudyisthestatisticalanalysis of thecases of SARS-COV2 infectionassociatedwith medical assistance in a family medicine office in Constanta in the period 2020-2022.
The author notes thediscrepancybetweenthephases of exponentialgrowth, plateauandlatency, thankstothedemanding monitoring of theprovisions of Law no. 55/15 May 2020, whichregulatestheactivity of preventingandcombatingtheeffects of the COVID-19 pandemic.
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