### Overview

MeSH Disease

Cough (106)

Fever (74)

Infections (58)

Disease (48)

Human Phenotype

Cough (106)

Fever (74)

Fatigue (24)

Pneumonia (23)

Sneeze (22)

Transmission

Seroprevalence
displaying 1 - 10 records in total 106
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### Extended lifetime of respiratory droplets in a turbulent vapour puff and its implications on airborne disease MESHD transmission TRANS

Authors: Kai Leong Chong; Chong Shen Ng; Naoki Hori; Rui Yang; Roberto Verzicco; Detlef Lohse

doi:10.1101/2020.08.04.20168468 Date: 2020-08-06 Source: medRxiv

To mitigate the COVID-19 pandemic, it is key to slow down the spreading of the life-threatening coronavirus (SARS-CoV-2). This spreading mainly occurs through virus-laden droplets expelled at speaking, screaming, shouting, singing, coughing MESHD coughing HP, sneezing MESHD sneezing HP, or even breathing [1-7]. To reduce infections MESHD through such respiratory droplets, authorities all over the world have introduced the so-called "2-meter distance rule" or "6-foot rule". However, there is increasing empirical evidence, e.g. through the analysis of super-spreading events [6, 8-11], that airborne transmission TRANS of the coronavirus over much larger distances plays a major role [1-3, 7, 12-15], with tremendous implications for the risk assessment of coronavirus transmission TRANS. It is key to better and fundamentally understand the environmental ambient conditions under which airborne transmission TRANS of the coronavirus is likely to occur, in order to be able to control and adapt them. Here we employ direct numerical simulations of a typical respiratory aerosol in a turbulent jet of the respiratory event within a Lagrangian-Eulerian approach [16-18] with 5000 droplets, coupled to the ambient velocity, temperature, and humidity fields to allow for exchange of mass and heat [19] and to realistically account for the droplet evaporation under different ambient conditions. We found that for an ambient relative humidity of 50% the lifetime of the smallest droplets of our study with initial diameter of 10 m gets extended by a factor of more than 30 as compared to what is suggested by the classical picture of Wells [20, 21], due to collective effects during droplet evaporation and the role of the respiratory humidity [22], while the larger droplets basically behave ballistically. With increasing ambient relative humidity the extension of the lifetimes of the small droplets further increases and goes up to 150 times for 90% relative humidity, implying more than two meters advection range of the respiratory droplets within one second. Smaller droplets live even longer and travel TRANS further. Our results may explain why COVID-19 superspreading events can occur for large ambient relative humidity such as in cooled-down meat-processing plants [10] or in pubs with poor ventilation. We anticipate our tool and approach to be starting points for larger parameter studies and for optimizing ventilation and indoor humidity controlling concepts, which in the upcoming autumn and winter both will be key in mitigating the COVID-19 pandemic.

### Airborne dispersion of droplets during coughing MESHD coughing HP: a physical model of viral transmission TRANS

Authors: Hongying Li; Fong Yew Leong; George Xu; Chang Wei Kang; Keng Hui Lim; Ban Hock Tan; Chian Min Loo

id:2008.01912v1 Date: 2020-08-05 Source: arXiv

The Covid-19 pandemic has focused attention on airborne transmission TRANS of viruses. Using realistic air flow simulation, we model droplet dispersion from coughing MESHD coughing HP and study the transmission risk TRANS related to SARS-CoV-2. Although most airborne droplets are 8-16 $\mu$m in diameter, the droplets with the highest transmission TRANS potential are, in fact, 32-40 $\mu$m. Use of face masks is therefore recommended for both personal and social protection. We found social distancing effective at reducing transmission TRANS potential across all droplet sizes. However, the presence of a human body 1 m away modifies the aerodynamics so that downstream droplet dispersion is enhanced, which has implications on safe distancing in queues. Based on median viral load, we found that an average of 0.55 viral copies is inhaled at 1 m distance per cough MESHD cough HP. Droplet evaporation results in significant reduction in droplet counts, but airborne transmission TRANS remains possible even under low humidity conditions.

### Extended lifetime of respiratory droplets in a turbulent vapour puff and its implications on airborne disease MESHD transmission TRANS

Authors: Kai Leong Chong; Chong Shen Ng; Naoki Hori; Rui Yang; Roberto Verzicco; Detlef Lohse

id:2008.01841v1 Date: 2020-08-04 Source: arXiv

To mitigate the COVID-19 pandemic, it is key to slow down the spreading of the life-threatening coronavirus (SARS-CoV-2). This spreading mainly occurs through virus-laden droplets expelled at speaking, coughing MESHD coughing HP, sneezing MESHD sneezing HP, or even breathing. To reduce infections MESHD through such respiratory droplets, authorities all over the world have introduced the so-called "2-meter distance rule" or "6-foot rule". However, there is increasing empirical evidence, e.g. through the analysis of super-spreading events, that airborne transmission TRANS of the coronavirus over much larger distances plays a major role with tremendous implications for the risk assessment of coronavirus transmission TRANS. Here we employ direct numerical simulations of a typical respiratory aerosol in a turbulent jet of the respiratory event within a Lagrangian-Eulerian approach with 5000 droplets, coupled to the ambient velocity, temperature, and humidity fields to allow for exchange of mass and heat and to realistically account for the droplet evaporation under different ambient conditions. We found that for an ambient relative humidity RH of 50% the lifetime of the smallest droplets of our study with initial diameter of 10 um gets extended by a factor of more than 30 as compared to what is suggested by the classical picture of Wells, due to collective effects during droplet evaporation and the role of the respiratory humidity, while the larger droplets basically behave ballistically. With increasing ambient RH the extension of the lifetimes of the small droplets further increases and goes up to 150 times for 90% RH, implying more than two meters advection range of the respiratory droplets within one second. Smaller droplets live even longer and travel TRANS further. Our results may explain why COVID-19 superspreading events can occur for large ambient RH such as in cooled-down meat-processing plants or in pubs with poor ventilation.

### Risk stratification as a tool to rationalize quarantine among health care workers exposed to COVID-19 cases - Evidence from a tertiary healthcare centre in India

Authors: Ravneet Kaur; Shashi Kant; Mohan Bairwa; Arvind Kumar; Shivram Dhakad; Vignesh Dwarakanathan; Aftab Ahmad; Pooja Pandey; Arti Kapil; Rakesh Lodha; Naveet Wig

doi:10.1101/2020.07.31.20166264 Date: 2020-08-04 Source: medRxiv

Background: Quarantine of healthcare workers (HCWs) exposed to COVID 19 confirmed cases TRANS is a well known strategy for limiting the transmission TRANS of infection MESHD. However, there is a need for evidence-based guidelines for the quarantine of HCWs in COVID 19. Methods: We describe our experience of contact tracing TRANS and risk stratification of 3853 HCWs who were exposed to confirmed COVID-19 cases in a tertiary health care institution in India. We developed an algorithm, on the basis of risk stratification, to rationalize quarantine among HCWs. Risk stratification was based on the duration of exposure, distance from the patient, and appropriateness of personal protection equipment (PPE) usage. Only high-risk contacts were quarantined for 14 days. They underwent testing for COVID 19 after five days of exposure, while low risk contacts continued their work with adherence to physical distancing, hand hygiene, and appropriate use of PPE. The low-risk contacts were encouraged to monitor for symptoms and report for COVID 19 screening if fever MESHD fever HP, cough MESHD cough HP, or shortness of breath occurred. We followed up all contacts for 14 days from the last exposure and observed for symptoms of COVID 19 and test positivity. Results and interpretation: Out of total 3853 contacts, 560 (14.5%) were categorized as high-risk contacts, and 40 of them were detected positive for COVID 19, with a test positivity rate of 7.1% (95% CI = 5.2, 9.6). Overall, 118 (3.1%) of all contacts tested positive. Our strategy prevented 3215 HCWs from being quarantined and saved 45,010 person-days of health workforce until June 8, 2020, in the institution. We conclude that exposure-based risk stratification and quarantine of HCWs is a viable strategy to prevent unnecessary quarantine, in a healthcare institution.

### Examining Australian's beliefs, misconceptions, and sources of information for COVID-19: A national online survey

Authors: Rae Thomas; Hannah Greenwood; Zoe A Michaleff; Eman Abukmail; Tammy Hoffmann; Kirsten J McCaffery; Leah Hardiman; Paul Glasziou

doi:10.1101/2020.07.27.20163204 Date: 2020-07-29 Source: medRxiv

Objective: Public cooperation to practice preventive health behaviours is essential to manage the transmission TRANS of infectious diseases MESHD such as COVID-19. We aimed to investigate beliefs about COVID-19 diagnosis, transmission TRANS and prevention that have the potential to impact the uptake of recommended public health strategies. Design: An online cross-sectional survey conducted May 8 to May 11 2020. Participants: A national sample of 1500 Australian adults TRANS with representative quotas for age TRANS and gender TRANS provided by online panel provider. Main outcome measure: Proportion of participants with correct/incorrect knowledge of COVID-19 preventive behaviours and reasons for misconceptions. Results: Of the 1802 potential participants contacted, 289 were excluded, 13 declined, and 1500 participated in the survey (response rate 83%). Most participants correctly identified washing your hands regularly with soap and water (92%) and staying at least 1.5m away from others (90%) could help prevent COVID-19. Over 40% (incorrectly) considered wearing gloves outside of the home would prevent them contracting COVID-19. Views about face masks were divided. Only 66% of participants correctly identified that regular use of antibiotics would not prevent COVID-19. Most participants (90%) identified fever MESHD fever HP, fatigue MESHD fatigue HP and cough MESHD cough HP as indicators of COVID-19. However, 42% of participants thought that being unable to hold your breath for 10 seconds without coughing MESHD coughing HP was an indicator of having the virus. The most frequently reported sources of COVID-19 information were commercial television channels (56%), the Australian Broadcasting Corporation (43%), and the Australian Government COVID-19 information app (31%). Conclusions: Public messaging about hand hygiene and physical distancing to prevent transmission TRANS appear to have been effective. However, there are clear, identified barriers for many individuals that have the potential to impede uptake or maintenance of these behaviours in the long-term. Currently these non-drug interventions are our only effective strategy to combat this pandemic. Ensuring ongoing adherence to is critical.

### Clinical characteristics of neonates with coronavirus disease MESHD 2019 (COVID-19): a systematic review﻿

Authors: Yuan Hu; Jing Xiong; Yuan Shi

doi:10.21203/rs.3.rs-50795/v1 Date: 2020-07-29 Source: ResearchSquare

This study aimed to summarize the existing literature on severe acute respiratory syndrome MESHD coronavirus 2 (SARS-CoV-2) infection in newborns to clarify the clinical features and outcomes of neonates with COVID-19. A systematic search was performed in PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang Data, and VIP databases from January 1, 2019 to April 30, 2020. The references of relevant studies were also searched. A descriptive summary was organized by aspects of clinical presentations (symptoms, laboratory examinations, and imaging) and outcomes. We identified 14 studies reporting 18 newborns with COVID-19. The most common clinical manifestations were fever MESHD fever HP (62.5%), shortness of breath (50.0%), diarrhea MESHD diarrhea HP/ vomiting MESHD vomiting HP/feeding intolerance(43.8%), cough MESHD cough HP (37.5%), dyspnea MESHD dyspnea HP (25.0%), and nasal congestion/runny nose/ sneeze MESHD sneeze HP(25.0%). Atypical symptoms included jaundice MESHD jaundice HP and convulsion. Lymphocyte numbers decreased in 5 cases, and radiographic findings were likely to show pneumonia MESHD pneumonia HP. All newborns recovered and discharged from the hospital, and there was no death MESHD.Conclusion: Clinical symptoms of neonatal SARS-CoV-2 infection MESHD are atypical, most of them are mild. Up to now, the prognosis of newborns is good, and there is no death MESHD. Intrauterine vertical transmission TRANS is possible, but confirmed evidence is still lacking. The Long-term follow-up of potential influences of SARS-CoV-2 infection MESHD on neonates need further exploration.

### Analyzing the dominant SARS-CoV-2 transmission TRANS routes towards an ab-initio SEIR model

Authors: Swetaprovo Chaudhuri; Saptarshi Basu; Abhishek Saha

id:2007.13596v2 Date: 2020-07-27 Source: arXiv

Identifying the relative importance of the different transmission TRANS routes of the SARS-CoV-2 virus is an urgent research priority. To that end, the different transmission TRANS routes, and their role in determining the evolution of the Covid-19 pandemic are analyzed in this work. Probability of infection MESHD caused by inhaling virus-laden droplets (initial, ejection diameters between $0.5-750\mu m$) and the corresponding desiccated nuclei that mostly encapsulate the virions post droplet evaporation, are individually calculated. At typical, air-conditioned yet quiescent indoor space, for average viral loading, cough MESHD cough HP droplets of initial diameter between $10-50 \mu m$ have the highest infection MESHD probability. However, by the time they are inhaled, the diameters reduce to about $1/6^{th}$ of their initial diameters. While the initially near unity infection MESHD probability due to droplets rapidly decays within the first $25s$, the small yet persistent infection MESHD probability of desiccated nuclei decays appreciably only by $\mathcal{O} (1000s)$, assuming the virus sustains equally well within the dried droplet nuclei as in the droplets. Combined with molecular collision theory adapted to calculate frequency of contact TRANS frequency of contact SERO between the susceptible population and the droplet/nuclei cloud, infection MESHD rate constants are derived ab-initio, leading to a SEIR model applicable for any respiratory event - vector combination. Viral load, minimum infectious dose, sensitivity SERO of the virus half-life to the phase of its vector and dilution of the respiratory jet/puff by the entraining air are shown to mechanistically determine specific physical modes of transmission TRANS and variation in the basic reproduction number TRANS $\mathcal{R}_0$, from first principle calculations.

### Probability of aerosol transmission TRANS of SARS-CoV-2

Authors: Daniel Bonn; Scott Howard Smith; Aernout Somsen; Cees van Rijn; Stefan Kooij; Lia van der Hoek; Reinout A Bem

doi:10.1101/2020.07.16.20155572 Date: 2020-07-18 Source: medRxiv

Transmission TRANS of SARS-CoV-2 leading to COVID-19 occurs through exhaled respiratory droplets from infected humans. Currently, however, there is much controversy over whether respiratory aerosol microdroplets play an important role as a route of transmission TRANS. By measuring and modeling the dynamics of exhaled respiratory droplets we can assess the relative contribution of aerosols in the spreading of SARS-CoV-2. We measure size distribution, total numbers and volumes of respiratory droplets, including aerosols, by speaking and coughing MESHD coughing HP from healthy subjects. Dynamic modelling of exhaled respiratory droplets allows to account for aerosol persistence times in confined public spaces. The probability of infection MESHD by inhalation of aerosols when breathing in the same space can then be estimated using current estimates of viral load and infectivity of SARS-CoV-2. In line with the current known reproduction numbers TRANS, our study of transmission TRANS of SARS-CoV-2 suggests that aerosol transmission TRANS is an inefficient route, in particular from non or mildly symptomatic individuals.

### Impact of Meteorological factors and population size on the transmission TRANS of Micro-size respiratory droplets based Coronavirus: A brief study of highly infected cities in Pakistan

doi:10.1101/2020.07.14.20153544 Date: 2020-07-17 Source: medRxiv

Ongoing Coronavirus epidemic (COVID-19) identified first in Wuhan, China posed huge impact on public health and economy around the globe. Both cough MESHD cough HP and sneeze MESHD sneeze HP based droplets or aerosols encapsulated COVID-19 particles are responsible for air borne transmission TRANS of this virus and caused unexpected escalation and high mortality worldwide. Current study intends to investigate correlation of COVID-19 epidemic with meteorological parameters particularly, temperature, rainfall, humidity, and wind speed along with population size. Data set of COVID-19 for highly infected cities of Pakistan was collected from the official website of National Institute of health (NIH). Spearman rank (rs) correlation coefficient test employed for data analysis revealed significant correlation between temperature minimum (TM), temperature average (TA), wind speed (WS) and population size (PS) with COVID-19 pandemic. Furthermore, receiver operating characteristics (ROC) curve was used to analyze the sensitivity SERO of TA, WS, and PS on transmission TRANS rate of COVID-19 in selected cities of Pakistan. The results obtained for sensitivity SERO and specificity analysis for all selected parameters signifies sensitivity SERO and direct correlation of COVID-19 transmission TRANS with temperature variation, WS and PS. Positive correlation and strong association of PS parameter with COVID-19 pandemic suggested need of more strict actions and control measures for highly populated cities. These findings will be helpful for health regulatory authorities and policymakers to take specific measures to combat COVID-19 epidemic in Pakistan.

### Clinical Characteristics of 107 Patients with COVID-19 in Ningbo, China: Single Center Experience Outside Hubei

Authors: Boming Wu; Junjie Li; Hongping Xuan; Nanhong Zheng; Honghua Ye; Yaoren Hu; Tong’en Chen; Hao Ying; Lingyan Fan; Qing Xie; Zike Sheng; Yin Ying

doi:10.21203/rs.3.rs-44830/v1 Date: 2020-07-17 Source: ResearchSquare