The ecological dynamics of the coronavirus epidemics during transmission from outside sources when
            R
            0
            is successfully managed below one

Since COVID-19 spread globally in early 2020 and was declared a pandemic by the World Health Organization (WHO) in March, many countries are managing the local epidemics effectively through intervention measures that limit transmission. The challenges of immigration of new infections into regions and asymptomatic infections remain. Standard deterministic compartmental models are inappropriate for sub- or peri-critical epidemics (reproductive number close to or less than one), so individual-based models are often used by simulating transmission from an infected person to others. However, to be realistic, these models require a large number of parameters, each with its own set of uncertainties and lack of analytic tractability. Here, we apply stochastic age-structured Leslie theory with a long history in ecological research to provide some new insights to epidemic dynamics fuelled by external imports. We model the dynamics of an epidemic when R 0 is below one, representing COVID-19 transmission following the successful application of intervention measures, and the transmission dynamics expected when infections migrate into a region. The model framework allows more rapid prediction of the shape and size of an epidemic to improve scaling of the response. During an epidemic when the numbers of infected individuals are rapidly changing, this will help clarify the situation of the pandemic and guide faster and more effective intervention.

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Effectiveness of Face Masks in Reducing the Spread of COVID-19: A Model-Based Analysis

Medical Decision Making ◽

10.1177/0272989x211019029 ◽

2021 ◽

pp. 0272989X2110190

Author(s):

Isabelle J. Rao ◽

Jacqueline J. Vallon ◽

Margaret L. Brandeau

Keyword(s):

New York ◽

Infected Individual ◽

Disease Model ◽

World Health ◽

Sensitivity Analyses ◽

Reproductive Number ◽

Social Distancing ◽

Health Organization ◽

Almost All ◽

Mask Effectiveness

Background The World Health Organization and US Centers for Disease Control and Prevention recommend that both infected and susceptible people wear face masks to protect against COVID-19. Methods We develop a dynamic disease model to assess the effectiveness of face masks in reducing the spread of COVID-19, during an initial outbreak and a later resurgence, as a function of mask effectiveness, coverage, intervention timing, and time horizon. We instantiate the model for the COVID-19 outbreak in New York, with sensitivity analyses on key natural history parameters. Results During the initial epidemic outbreak, with no social distancing, only 100% coverage of masks with high effectiveness can reduce the effective reproductive number [Formula: see text] below 1. During a resurgence, with lowered transmission rates due to social distancing measures, masks with medium effectiveness at 80% coverage can reduce [Formula: see text] below 1 but cannot do so if individuals relax social distancing efforts. Full mask coverage could significantly improve outcomes during a resurgence: with social distancing, masks with at least medium effectiveness could reduce [Formula: see text] below 1 and avert almost all infections, even with intervention fatigue. For coverage levels below 100%, prioritizing masks that reduce the risk of an infected individual from spreading the infection rather than the risk of a susceptible individual from getting infected yields the greatest benefit. Limitations Data regarding COVID-19 transmission are uncertain, and empirical evidence on mask effectiveness is limited. Our analyses assume homogeneous mixing, providing an upper bound on mask effectiveness. Conclusions Even moderately effective face masks can play a role in reducing the spread of COVID-19, particularly with full coverage, but should be combined with social distancing measures to reduce [Formula: see text] below 1. [Box: see text]

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Leukopenia of Asymptomatic COVID-19 Infections under 18 Years Old in Recovery Stage

10.21203/rs.3.rs-29855/v1 ◽

2020 ◽

Author(s):

Wei Zhang ◽

Youshu Yuan ◽

Zhengqiao Yang ◽

Jinxia Fu ◽

Yun Zhang ◽

...

Keyword(s):

Treatment Period ◽

Clinical Characteristics ◽

Clinical Laboratory ◽

World Health ◽

Recovery Stage ◽

Familial Cluster ◽

Asymptomatic Infections ◽

The Difference ◽

Novel Coronavirus ◽

Health Organization

Abstract Background In December, 2019, a type of novel coronavirus which was designated novel coronavirus 2019 (2019-nCoV) by World Health Organization (WHO) occurred in Wuhan, Hubei, China. The epidemiological and clinical characteristics of those patients under 18 years old in the recovery stage are limited. To compare the difference of epidemiological and clinical characteristics of COVID-19 involving 25 patients under 18 years old in recovery stage between confirmed and asymptomatic infections.Methods Retrospective, single-center cohort study of COVID-19 involving 25 patients under 18 years old in the recovery stage at Guizhou Provincial Staff Hospital in Guiyang, China, from January 29, to March 31, 2020; final date of follow-up was April 22. Epidemiological, demographic, clinical, laboratory, radiological, and treatment data were collected and analyzed. Epidemiological and clinical characteristics of confirmed COVID-19 infections and asymptomatic infections were compared.Results Among the 25 COVID infections under 18 years old, 16 (64%) were mild or moderate confirmed cases, and 9 (36%) were asymptomatic. The shortest treatment period was 6 days, the longest 26 days, and the average treatment period 14 days. Four cases (44.4%) had visited Wuhan or had a living story in the city. There were 9 (100%) asymptomatic cases were familial cluster outbreak, with an average infection number was 6 cases among all families. The number of asymptomatic COVID-19 infections’ Leukopenia were significantly more than confirmed cases (p = 0.04).Conclusions Leukopenia mostly occurred in asymptomatic COVID-19 infections under 18 years old compared with the confirmed patients.

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Possibility of Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) through Wastewater in Developing Countries

Water ◽

10.3390/w13233412 ◽

2021 ◽

Vol 13 (23) ◽

pp. 3412

Author(s):

Sarmila Tandukar ◽

Rajendra Khanal ◽

Rija Manandhar ◽

Ashok Pandey ◽

Niva Sthapit ◽

...

Keyword(s):

Developing Countries ◽

Severe Acute Respiratory Syndrome ◽

Municipal Wastewater ◽

Disease Outbreaks ◽

Severe Infection ◽

World Health ◽

Mass Detection ◽

Bodily Fluids ◽

Intervention Measures ◽

Health Organization

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was detected in Wuhan, China. The clinical manifestation of COVID-19 varies from asymptomatic to severe infection. The World Health Organization has reported over 248 million cases and more than 5 million deaths worldwide due to COVID-19. Additionally, developing countries are still struggling to achieve the rapid diagnosis of suspected cases to break the chain of transmission of COVID-19. There may be undiagnosed or missing cases in these countries. Various studies have reported that the SARS-CoV-2 can be discharged in the stool and other bodily fluids. Moreover, it is possible that SARS-CoV-2 can be transmitted in the environment via municipal wastewater. In developing countries, such as Nepal, the molecular-based diagnosis of SARS-CoV-2 for the entire population is not practical owing to insufficient diagnostic material and budgetary constraints. Wastewater-based epidemiology (WBE) is a promising public health surveillance tool for the early warning of disease outbreaks and the understanding the prevalence of viruses for the development of intervention measures. This study highlights the importance of the utilization of WBE as an alternative tool for the mass detection of SARS-CoV-2 RNA in wastewater.

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Epidemiological and clinical characteristics of severe fever with thrombocytopenia syndrome bunyavirus human-to-human transmission

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0009037 ◽

2021 ◽

Vol 15 (4) ◽

pp. e0009037

Author(s):

Xinyu Fang ◽

Jianli Hu ◽

Zhihang Peng ◽

Qigang Dai ◽

Wendong Liu ◽

...

Keyword(s):

South Korea ◽

Clinical Characteristics ◽

Eastern China ◽

Transmission Risk ◽

Basic Reproductive Number ◽

World Health ◽

Reproductive Number ◽

Health Organization ◽

Associated Risk Factors ◽

Severe Fever

Background Severe fever with thrombocytopenia syndrome (SFTS) was listed as one of the most severe infectious disease by world health organization in 2017. It can mostly be transmitted by tick bite, while human-to-human transmission has occurred on multiple occasions. This study aimed to explore the epidemiological and clinical characteristics and make risk analysis of SFTS human-to-human transmission. Methods Descriptive and spatial methods were employed to illustrate the epidemiological and clinical characteristics of SFTS human-to-human transmission. The risk of SFTS human-to-human transmission was accessed through secondary attack rate (SAR) and basic reproductive number (R0). Logistic regression analysis was used to identify the associated risk factors. Results A total of 27 clusters of SFTS human-to-human transmission were reported in China and South Korea during 1996–2019. It mainly occurred among elder people in May, June and October in central and eastern China. The secondary cases developed milder clinical manifestation and better outcome than the index cases. The incubation period was 10.0 days (IQR:8.0–12.0), SAR was 1.72%-55.00%, and the average R0 to be 0.13 (95%CI:0.11–0.16). Being blood relatives of the index case, direct blood/bloody secretion contact and bloody droplet contact had more risk of infection (OR = 6.35(95%CI:3.26–12.37), 38.01 (95%CI,19.73–73.23), 2.27 (95%CI,1.01–5.19)). Conclusions SFTS human-to-human transmission in China and South Korea during 1996–2019 had obvious spatio-temporal distinction. Ongoing assessment of this transmission risk is crucial for public health authorities though it continues to be low now.

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Ambient nitrogen dioxide pollution and spread ability of COVID-19 in Chinese cities

10.1101/2020.03.31.20048595 ◽

2020 ◽

Cited By ~ 5

Author(s):

Ye Yao ◽

Jinhua Pan ◽

Zhixi Liu ◽

Xia Meng ◽

Weidong Wang ◽

...

Keyword(s):

Nitrogen Dioxide ◽

Respiratory Diseases ◽

World Health ◽

Virus Infections ◽

High Exposure ◽

Chinese Cities ◽

Intervention Measures ◽

The World ◽

Health Organization ◽

And Control

The Coronavirus (COVID-19) epidemic, which was first reported in December 2019 in Wuhan, China, has caused 219,331 confirmed cases as of 20 March 2020, with 81,301 cases being reported in China. It has been declared a pandemic by the World Health Organization in 11 March 2020 (1). Although massive intervention measures have been implemented in China (e.g. shutting down cities, extending holidays and travel ban) and many other countries, the spread of the disease are unlikely to be stopped over the world shortly. It is becoming evident that environmental factors are associated with seasonality of respiratory-borne diseases’ epidemics (2). Previous studies have suggested that ambient nitrogen dioxide (NO2) exposure may play a role in the phenotypes of respiratory diseases, including, but not limited to, influenza, asthma and severe acute respiratory syndrome (SARS). NO2), for example, might increase the susceptibility of adults to virus infections (3). High exposure to NO2 before the start of a respiratory viral infection is associated with the severity of asthma exacerbation (4). This study aims to assess the associations of ambient NO2 levels with spread ability of COVID-19 across 63 Chinese cities, and provides information for the further prevention and control of COVID-19.

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SARS-CoV-2 infection hospitalization, severity, criticality, and fatality rates

10.1101/2020.11.29.20240416 ◽

2020 ◽

Cited By ~ 1

Author(s):

Shaheen Seedat ◽

Hiam Chemaitelly ◽

Houssein Ayoub ◽

Monia Makhoul ◽

Ghina R. Mumtaz ◽

...

Keyword(s):

Intensive Care Unit ◽

Intensive Care ◽

Acute Care ◽

World Health ◽

Fatality Rate ◽

Age Dependence ◽

Hospitalization Rates ◽

Infection Disease ◽

Age Structured ◽

Health Organization

AbstractBackgroundThis study aimed to estimate the age-stratified and overall morbidity and mortality rates of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection based on an analysis of the pervasive SARS-CoV-2 epidemic in Qatar, a country with <9% of the population being ≥50 years of age.MethodsInfection disease outcomes were investigated using a Bayesian approach applied to an age-structured mathematical model describing SARS-CoV-2 transmission and disease progression in the population. The model was fitted to infection and disease time-series and age-stratified data. Two separate criteria for classifying morbidity were used: one based on actual recorded hospital admission (acute-care or intensive-care-unit hospitalization) and one based on clinical presentation as per World Health Organization classification of disease severity or criticality.ResultsAll outcomes showed very strong age dependence, with low values for those <50 years of age, but rapidly growing rates for those ≥50 years of age. The strong age dependence was particularly pronounced for infection criticality rate and infection fatality rate. Infection acute-care and intensive-care-unit bed hospitalization rates were estimated at 13.10 (95% CI: 12.82-13.24) and 1.60 (95% CI: 1.58-1.61) per 1,000 infections, respectively. Infection severity and criticality rates were estimated at 3.06 (95% CI: 3.01-3.10) and 0.68 (95% CI: 0.67-0.68) per 1,000 infections, respectively. Infection fatality rate was estimated at 1.85 (95% CI: 1.74-1.95) per 10,000 infections.ConclusionsSARS-CoV-2 severity and fatality in Qatar was not high and demonstrated a very strong age dependence with <4 infections in every 1,000 being severe or critical and <2 in every 10,000 being fatal. Epidemic expansion in nations with young populations may lead to lower disease burden than previously thought.

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Description and analysis of primary care-based COVID-19 interventions in Colombia

Medwave ◽

10.5867/medwave.2021.03.8147 ◽

2021 ◽

Vol 21 (03) ◽

pp. e8147-e8147

Author(s):

Erwin Hernando Hernández Rincón ◽

Juan Pablo Pimentel González ◽

Manuel Felipe Aramendiz Narváez ◽

Raúl Andrés Araujo Tabares ◽

Julián Mateo Roa González

Keyword(s):

Primary Care ◽

Large Scale ◽

Community Action ◽

World Health ◽

Narrative Synthesis ◽

Opportunity To Respond ◽

Intervention Measures ◽

Remote Services ◽

Pan American ◽

Health Organization

Introduction The COVID-19 pandemic was declared in early 2020, requiring different prevention and intervention measures on a large scale. In the case of Colombia, a series of measures focused on isolation and remote services provision were introduced in a context marked by health inequities. This article reviews the theoretical and normative references on primary care interventions in the Colombian response to the COVID-19 pandemic. Methods A literature review was conducted in PubMed, LILACS, MEDLINE, and official documents and regulations issued in Colombia, the World Health Organization, and the Pan American Health Organization. A narrative synthesis was done of 33 documents based on their contribution to the implementation of primary care in Colombia and their role in the pandemic. Results The information was organized into two categories: Actions taken in Colombia in response to COVID-19 and Opportunities in primary care in response to COVID-19. Colombia’s actions were contrasted with world experience. Better pandemic control was found in countries that adopted primary care as a response. Primary care has strengthened the handling of the pandemic through community action, the provision of coordinated services, mental health inclusion, and the adoption of telemedicine processes. Conclusions In Colombia, primary care is presented as an opportunity to respond to the COVID-19 pandemic and the problems and needs derived from this situation. However, despite the above, there is resistance in the country to adopt this type of approach and complement the hospital-centric model to face the pandemic.

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A Review of Asymptomatic and Subclinical Middle East Respiratory Syndrome Coronavirus Infections

Epidemiologic Reviews ◽

10.1093/epirev/mxz009 ◽

2019 ◽

Vol 41 (1) ◽

pp. 69-81 ◽

Cited By ~ 8

Author(s):

Rebecca Grant ◽

Mamunur Rahman Malik ◽

Amgad Elkholy ◽

Maria D Van Kerkhove

Keyword(s):

Health Care ◽

Middle East ◽

World Health Organization ◽

Health Care Facilities ◽

Middle East Respiratory Syndrome ◽

World Health ◽

Health Care Settings ◽

The World ◽

Asymptomatic Infections ◽

Health Organization

Abstract The epidemiology of Middle East respiratory syndrome coronavirus (MERS-CoV) since 2012 has been largely characterized by recurrent zoonotic spillover from dromedary camels followed by limited human-to-human transmission, predominantly in health-care settings. The full extent of infection of MERS-CoV is not clear, nor is the extent and/or role of asymptomatic infections in transmission. We conducted a review of molecular and serological investigations through PubMed and EMBASE from September 2012 to November 15, 2018, to measure subclinical or asymptomatic MERS-CoV infection within and outside of health-care settings. We performed retrospective analysis of laboratory-confirmed MERS-CoV infections reported to the World Health Organization to November 27, 2018, to summarize what is known about asymptomatic infections identified through national surveillance systems. We identified 23 studies reporting evidence of MERS-CoV infection outside of health-care settings, mainly of camel workers, with seroprevalence ranges of 0%–67% depending on the study location. We identified 20 studies in health-care settings of health-care worker (HCW) and family contacts, of which 11 documented molecular evidence of MERS-CoV infection among asymptomatic contacts. Since 2012, 298 laboratory-confirmed cases were reported as asymptomatic to the World Health Organization, 164 of whom were HCWs. The potential to transmit MERS-CoV to others has been demonstrated in viral-shedding studies of asymptomatic MERS infections. Our results highlight the possibility for onward transmission of MERS-CoV from asymptomatic individuals. Screening of HCW contacts of patients with confirmed MERS-CoV is currently recommended, but systematic screening of non-HCW contacts outside of health-care facilities should be encouraged.

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A comprehensive analysis of R0 with different lockdown phase during covid-19 in India (Preprint)

10.2196/preprints.22506 ◽

2020 ◽

Author(s):

Mayank Chhabra ◽

Tushant Agrawal

Keyword(s):

Preventive Measure ◽

World Health ◽

Reproductive Number ◽

Family Welfare ◽

R Software ◽

Policy Makers ◽

Novel Method ◽

Health Organization ◽

Result Analysis ◽

Spread Of Infection

BACKGROUND Background: World Health organization declared Covid-19 as an outbreak, hence preventive measure like lockdown should be taken to control the spread of infection. OBJECTIVE Objective: This study offers an exhaustive analysis of the reproductive number (R0) in India with major intervention for COVID-19 outbreaks and analysed the lockdown effects on the Covid-19. METHODS Methodology: Covid-19 data extracted from Ministry of Health and Family Welfare, Government of India. Then, a novel method implemented in the incidence and Optimum function in desolve package to the data of cumulative daily new confirmed cases for robustly estimating the reproduction number in the R software. RESULTS Result: Analysis has been seen that the lockdown was really quite as effective, India has already shown a major steady decline. The growth rate has fluctuated about 20 percent with trend line projections in various lockdown. A comparative analysis gives an idea of decline in value of R0 from 1.73 to 1.08. Annotation plot showing the predicted R0 values based on previous lockdown in month of June and July. CONCLUSIONS Conclusion: Without lockdown, the growth might not have been contained in India and may have gone into the exponential zone. We show that, the lockdown in India was fairly successful. The effect partial lifting of the lockdown (unlock) is also seen in the results, in terms of increment in R0 values. Hence this study provides a platform for policy makers and government authorities for implementing the strategies to prevent the spread of infection.

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A comprehensive analysis of R0 with different lockdown phase during covid-19 in India

10.1101/2020.07.10.20150631 ◽

2020 ◽

Author(s):

Mayank Chhabra ◽

Tushant Agrawal

Keyword(s):

Preventive Measure ◽

World Health ◽

Reproductive Number ◽

Family Welfare ◽

R Software ◽

Policy Makers ◽

Novel Method ◽

Health Organization ◽

Result Analysis ◽

Spread Of Infection

Background: World Health organization declared Covid-19 as an outbreak, hence preventive measure like lockdown should be taken to control the spread of infection. This study offers an exhaustive analysis of the reproductive number (R0) in India with major intervention for COVID-19 outbreaks and analysed the lockdown effects on the Covid-19. Methodology: Covid-19 data extracted from Ministry of Health and Family Welfare, Government of India. Then, a novel method implemented in the incidence and Optimum function in desolve package to the data of cumulative daily new confirmed cases for robustly estimating the reproduction number in the R software. Result: Analysis has been seen that the lockdown was really quite as effective, India has already shown a major steady decline. The growth rate has fluctuated about 20 percent with trend line projections in various lockdown. A comparative analysis gives an idea of decline in value of R0 from 1.73 to 1.08. Annotation plot showing the predicted R0 values based on previous lockdown in month of June and July. Conclusion: Without lockdown, the growth might not have been contained in India and may have gone into the exponential zone. We show that, the lockdown in India was fairly successful. The effect partial lifting of the lockdown (unlock) is also seen in the results, in terms of increment in R0 values. Hence this study provides a platform for policy makers and government authorities for implementing the strategies to prevent the spread of infection.

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