scholarly journals Modeling the Effect of Lockdown Timing as a COVID-19 Control Measure in Countries with Differing Social Contacts

2020 ◽  
Author(s):  
Tamer Oraby ◽  
Michael G Tyshenko ◽  
Jose Campo Maldonado ◽  
Kristina Vatcheva ◽  
Susie Elsaadany ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Control Measure ◽  
Social Contact ◽  
Control Measures ◽  
Tunneling Effect ◽  
Continuous Time Markov Chain ◽  
Social Contacts ◽  
Application Timing ◽  
Hospital Capacity ◽  
Absolute Effect

AbstractThe application, timing, and duration of lockdown strategies during a pandemic remain poorly quantified with regards to expected public health outcomes. Previous projection models have reached conflicting conclusions about the effect of complete lockdowns on COVID-19 outcomes. We developed a stochastic continuous-time Markov chain (CTMC) model with eight states including the environment (SEAMHQRD-V), and derived a formula for the basic reproduction number, R0, for that model. Applying the R0 formula as a function in previously-published social contact matrices from 152 countries, we produced the distribution and four categories of possible R0 for the 152 countries and chose one country from each quarter as a representative for four social contact categories (Canada, China, Mexico, and Niger). The model was then used to predict the effects of lockdown timing in those four categories through the representative countries. The analysis for the effect of a lockdown was performed without the influence of the other control measures, like social distancing and mask wearing, to quantify its absolute effect. Hypothetical lockdown timing was shown to be the critical parameter in ameliorating pandemic peak incidence. More importantly, we found that well-timed lockdowns can split the peak of hospitalizations into two smaller distant peaks while extending the overall pandemic duration. The timing of lockdowns reveals that a “tunneling” effect on incidence can be achieved to bypass the peak and prevent pandemic caseloads from exceeding hospital capacity.

scholarly journals Modeling the effect of lockdown timing as a COVID-19 control measure in countries with differing social contacts

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tamer Oraby ◽  
Michael G. Tyshenko ◽  
Jose Campo Maldonado ◽  
Kristina Vatcheva ◽  
Susie Elsaadany ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Control Measure ◽  
Social Contact ◽  
Control Measures ◽  
Tunneling Effect ◽  
Continuous Time Markov Chain ◽  
Social Contacts ◽  
Application Timing ◽  
Hospital Capacity ◽  
Absolute Effect

AbstractThe application, timing, and duration of lockdown strategies during a pandemic remain poorly quantified with regards to expected public health outcomes. Previous projection models have reached conflicting conclusions about the effect of complete lockdowns on COVID-19 outcomes. We developed a stochastic continuous-time Markov chain (CTMC) model with eight states including the environment (SEAMHQRD-V), and derived a formula for the basic reproduction number, R0, for that model. Applying the $${R}_{0}$$ R 0 formula as a function in previously-published social contact matrices from 152 countries, we produced the distribution and four categories of possible $${R}_{0}$$ R 0 for the 152 countries and chose one country from each quarter as a representative for four social contact categories (Canada, China, Mexico, and Niger). The model was then used to predict the effects of lockdown timing in those four categories through the representative countries. The analysis for the effect of a lockdown was performed without the influence of the other control measures, like social distancing and mask wearing, to quantify its absolute effect. Hypothetical lockdown timing was shown to be the critical parameter in ameliorating pandemic peak incidence. More importantly, we found that well-timed lockdowns can split the peak of hospitalizations into two smaller distant peaks while extending the overall pandemic duration. The timing of lockdowns reveals that a “tunneling” effect on incidence can be achieved to bypass the peak and prevent pandemic caseloads from exceeding hospital capacity.

Social contact patterns and leprosy disease: a case-control study in Bangladesh

2012 ◽  
Vol 141 (3) ◽  
pp. 573-581 ◽  
Author(s):  
S. G. FEENSTRA ◽  
Q. NAHAR ◽  
D. PAHAN ◽  
L. OSKAM ◽  
J. H. RICHARDUS
Keyword(s):  
Case Control Study ◽  
Important Determinant ◽  
Social Contact ◽  
Risk Groups ◽  
Case Control ◽  
Control Measures ◽  
Social Contacts ◽  
Contact Patterns ◽  
Endemic Areas ◽  
Control Study

SUMMARYSocioeconomic and culturally defined social contact patterns are expected to be an important determinant in the continuing transmission of Mycobacterium leprae in leprosy-endemic areas. In a case-control study in two districts in Bangladesh, we assessed the association between social contact patterns and the risk of acquiring clinical leprosy. Social contacts of 90 recently diagnosed patients were compared to those of 199 controls. Leprosy was associated with a more intensive social contact pattern in the home [odds ratio (OR) 1·09, 95% confidence interval (CI) 1·00–1·19, P = 0·043] and in the nearby neighbourhood (OR 1·07, 95% CI 1·03–1·11, P = 0·001). Although it is known that M. leprae spreads most easily within households of infected persons, in endemic areas social contacts within the neighbourhood, village or urban ward, also appear to be important for transmission. We advise that disease control measures in leprosy-endemic areas should not be limited to households, but include high-risk groups in the nearby neighbourhood of patients.

scholarly journals Epidemiology of SARS-CoV-2

Infection ◽  
2020 ◽  
Author(s):  
Bernd Salzberger ◽  
Felix Buder ◽  
Benedikt Lampl ◽  
Boris Ehrenstein ◽  
Florian Hitzenbichler ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Current Knowledge ◽  
Multiorgan Failure ◽  
Medical Personnel ◽  
Control Measures ◽  
Current Estimate ◽  
Social Contacts ◽  
Age Dependent ◽  
Lower Limits ◽  
Epidemiologic Features

Abstract Purpose SARS-CoV-2 is a recently emerged ß-coronavirus. Here we present the current knowledge on its epidemiologic features. Methods Non-systematic review. Results SARS-CoV-2 replicates in the upper and lower respiratory tract. It is mainly transmitted by droplets and aerosols from asymptomatic and symptomatic infected subjects. The consensus estimate for the basis reproduction number (R0) is between 2 and 3, and the median incubation period is 5.7 (range 2–14) days. Similar to SARS and MERS, superspreading events have been reported, the dispersion parameter (kappa) is estimated at 0.1. Most infections are uncomplicated, and 5–10% of patients are hospitalized, mainly due to pneumonia with severe inflammation. Complications are respiratory and multiorgan failure; risk factors for complicated disease are higher age, hypertension, diabetes, chronic cardiovascular, chronic pulmonary disease and immunodeficiency. Nosocomial and infections in medical personnel have been reported. Drastic reductions of social contacts have been implemented in many countries with outbreaks of SARS-CoV-2, leading to rapid reductions. Most interventions have used bundles, but which of the measures have been more or less effective is still unknown. The current estimate for the infection’s fatality rate is 0.5–1%. Using current models of age-dependent infection fatality rates, upper and lower limits for the attack rate in Germany can be estimated between 0.4 and 1.6%, lower than in most European countries. Conclusions Despite a rapid worldwide spread, attack rates have been low in most regions, demonstrating the efficacy of control measures.

scholarly journals Integrated vaccination and physical distancing interventions to prevent future COVID-19 waves

2021 ◽  
Author(s):  
Bo Huang ◽  
Jionghua Wang ◽  
Jixuan Cai ◽  
Shiqi Yao ◽  
Paul Kay Sheung CHAN ◽  
...  
Keyword(s):  
Population Density ◽  
Disease Transmission ◽  
Reproduction Number ◽  
Social Contact ◽  
Preventive Interventions ◽  
Population Densities ◽  
Social Contacts ◽  
Intervention Measures ◽  
The Impact ◽  
Mobility Reduction

Abstract COVID-19 resurgences worldwide have posed significant challenges to the formulation of preventive interventions, especially given that the effects of physical distancing and upcoming vaccines on reducing susceptible social contacts and eventually halting transmission are still unclear. Using anonymized mobile geolocation data in China, we devised a mobility-associated social contact index to quantify the impact of both physical distancing and vaccination measures in a unified way such that the gap between intervention measures and disease transmission can be explicitly bridged. This index explained 90% of the variance in the changing reproduction number of infections across the COVID-19 outbreak in Wuhan, and was validated in six other cities of different population densities. Our simulations showed that vaccination combined with physical distancing can contain resurgences without relying on mobility reduction, whereas a gradual vaccination process alone cannot achieve this. Further, for cities with medium-population density, vaccination can shorten the duration of physical distancing by 36%-78%, whereas for cities with high-population density, infection numbers can well be controlled through moderate physical distancing. These findings provide guidance on tailoring and implementing comprehensive interventions for cities with varying population densities.

The Effect Of Social Contacts On The Spreads Of Covid-19 In Indonesia

2020 ◽  
Vol 7 (6) ◽  
pp. 233-242
Author(s):  
Mariatul Fadilah ◽  
Dewi Arsinta
Keyword(s):  
Infectious Disease ◽  
Logistic Regression ◽  
Regression Analysis ◽  
Reproduction Number ◽  
Social Contact ◽  
Human Interaction ◽  
Infected Person ◽  
Social Contacts ◽  
Low Education ◽  
Education Levels

Introduction: Covid-19 is an infectious disease. Matrix that is often used to identify transmission of infectious diseases dynamics is Basic Reproduction Number (R0). R0 is influenced by 3 parameters there are transmissibility (τ), average contact (c) and duration of infectiousness (d). Transmissibility and duration of infectiousness are constant values. The value of R0 will fluctuate if the rate of human interaction varies. The value of social contact different in every country. In Indonesia, there are no studies that discuss the value of social contact. Therefore researchers aims to find out these values and determine their effect on the spread of Covid-19. Method: This research was a descriptive observational study. Aims of the study is evaluate the pattern of social contact associated with the spread of covid-19. Data was collected using POLYMOD questionnaire that distributed via google form. The research sample was Indonesian people who were reached by distributing questionnaires. The data obtained then analyzed using the SPSS program to find the frequency distribution, mean of social contact and logistic regression analysis. Results: From this study, 6464 contacts were obtained from 1032 respondents with average number of contacts 6.26 and R0 2.191. Conclusion: The higher of contact value the higher risk of transmission. The R0 value obtained is 2.191, so one infected person might be able to transmit it to two other people around them. Individuals who are most at risk for transmission is male with low education levels and students.

Characterizing the effectiveness of COVID-19 mitigation measures: A data-centric approach (Preprint)

2020 ◽  
Author(s):  
Lukman Olagoke ◽  
Ahmet E. Topcu
Keyword(s):  
Control Measure ◽  
Control Measures ◽  
World Health ◽  
Mitigation Measures ◽  
Effective Control ◽  
The World ◽  
Decision Making Processes ◽  
And Performance ◽  
Health Organization ◽  
The Impact

BACKGROUND COVID-19 represents a serious threat to both national health and economic systems. To curb this pandemic, the World Health Organization (WHO) issued a series of COVID-19 public safety guidelines. Different countries around the world initiated different measures in line with the WHO guidelines to mitigate and investigate the spread of COVID-19 in their territories. OBJECTIVE The aim of this paper is to quantitatively evaluate the effectiveness of these control measures using a data-centric approach. METHODS We begin with a simple text analysis of coronavirus-related articles and show that reports on similar outbreaks in the past strongly proposed similar control measures. This reaffirms the fact that these control measures are in order. Subsequently, we propose a simple performance statistic that quantifies general performance and performance under the different measures that were initiated. A density based clustering of based on performance statistic was carried out to group countries based on performance. RESULTS The performance statistic helps evaluate quantitatively the impact of COVID-19 control measures. Countries tend show variability in performance under different control measures. The performance statistic has negative correlation with cases of death which is a useful characteristics for COVID-19 control measure performance analysis. A web-based time-line visualization that enables comparison of performances and cases across continents and subregions is presented. CONCLUSIONS The performance metric is relevant for the analysis of the impact of COVID-19 control measures. This can help caregivers and policymakers identify effective control measures and reduce cases of death due to COVID-19. The interactive web visualizer provides easily digested and quick feedback to augment decision-making processes in the COVID-19 response measures evaluation. CLINICALTRIAL Not Applicable

scholarly journals Analysis and prediction of the coronavirus disease epidemic in China based on an individual-based model

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zuiyuan Guo ◽  
Dan Xiao
Keyword(s):  
Reproduction Number ◽  
Control Measures ◽  
Cumulative Number ◽  
Individual Based Model ◽  
Whole Process ◽  
Coordinate Descent Algorithm ◽  
Initial Stage ◽  
The Government ◽  
Prevention And Control Measures ◽  
And Control

AbstractWe established a stochastic individual-based model and simulated the whole process of occurrence, development, and control of the coronavirus disease epidemic and the infectors and patients leaving Hubei Province before the traffic was closed in China. Additionally, the basic reproduction number (R0) and number of infectors and patients who left Hubei were estimated using the coordinate descent algorithm. The median R0 at the initial stage of the epidemic was 4.97 (95% confidence interval [CI] 4.82–5.17). Before the traffic lockdown was implemented in Hubei, 2000 (95% CI 1982–2030) infectors and patients had left Hubei and traveled throughout the country. The model estimated that if the government had taken prevention and control measures 1 day later, the cumulative number of laboratory-confirmed patients in the whole country would have increased by 32.1%. If the lockdown of Hubei was imposed 1 day in advance, the cumulative number of laboratory-confirmed patients in other provinces would have decreased by 7.7%. The stochastic model could fit the officially issued data well and simulate the evolution process of the epidemic. The intervention measurements nationwide have effectively curbed the human-to-human transmission of severe acute respiratory syndrome coronavirus 2.

scholarly journals Heterogeneity and effectiveness analysis of COVID-19 prevention and control in major cities in China through time-varying reproduction number estimation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Qing Cheng ◽  
Zeyi Liu ◽  
Guangquan Cheng ◽  
Jincai Huang
Keyword(s):  
Prevention And Control ◽  
Large Scale ◽  
Reproduction Number ◽  
Correlation Method ◽  
Control Measures ◽  
Time Varying ◽  
Short Period ◽  
Significant Difference ◽  
Prevention And Control Measures ◽  
And Control

AbstractBeginning on December 31, 2019, the large-scale novel coronavirus disease 2019 (COVID-19) emerged in China. Tracking and analysing the heterogeneity and effectiveness of cities’ prevention and control of the COVID-19 epidemic is essential to design and adjust epidemic prevention and control measures. The number of newly confirmed cases in 25 of China’s most-affected cities for the COVID-19 epidemic from January 11 to February 10 was collected. The heterogeneity and effectiveness of these 25 cities’ prevention and control measures for COVID-19 were analysed by using an estimated time-varying reproduction number method and a serial correlation method. The results showed that the effective reproduction number (R) in 25 cities showed a downward trend overall, but there was a significant difference in the R change trends among cities, indicating that there was heterogeneity in the spread and control of COVID-19 in cities. Moreover, the COVID-19 control in 21 of 25 cities was effective, and the risk of infection decreased because their R had dropped below 1 by February 10, 2020. In contrast, the cities of Wuhan, Tianmen, Ezhou and Enshi still had difficulty effectively controlling the COVID-19 epidemic in a short period of time because their R was greater than 1.

scholarly journals Using Commercial Compost as Control Measures against Cucumber Root-Rot Disease

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Kamel Kamal Sabet ◽  
Magdy Mohamed Saber ◽  
Mohamed Adel-Aziz El-Naggar ◽  
Nehal Samy El-Mougy ◽  
Hatem Mohamed El-Deeb ◽  
...  
Keyword(s):  
Root Rot ◽  
Control Measure ◽  
Disease Incidence ◽  
Pathogenic Fungi ◽  
Pythium Ultimum ◽  
Control Measures ◽  
Infested Soil ◽  
Fungal Isolates ◽  
Cucumber Root

Five commercial composts were evaluated to suppress the root-rot pathogens (Fusarium solani (Mart.) App. and Wr, Pythium ultimum Trow, Rhizoctonia solani Kuhn, and Sclerotium rolfsii Sacc.) of cucumber plants under in vitro and greenhouse conditions. In vitro tests showed that all tested unautoclaved and unfiltrated composts water extracts (CWEs) had inhibitor effect against pathogenic fungi, compared to autoclaved and filtrated ones. Also, the inhibitor effects of 40 bacteria and 15 fungi isolated from composts were tested against the mycelial growth of cucumber root-rot pathogens. Twenty two bacteria and twelve fungal isolates had antagonistic effect against root-rot pathogens. The antagonistic fungal isolates were identified as 6 isolates belong to the genus Aspergillus spp., 5 isolates belong to the genus Penicillium spp. and one isolate belong to the genus Chaetomium spp. Under greenhouse conditions, the obtained results in pot experiment using artificial infested soil with cucumber root-rot pathogens showed that the compost amended soil reduced the percentage of disease incidence, pathogenic fungi population, and improved the cucumber vegetative parameters as shoot length, root length, fresh weight, and dry weight. These results suggested that composts are consequently considered as control measure against cucumber root-rot pathogens.

scholarly journals Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England

Science ◽  
2021 ◽  
Vol 372 (6538) ◽  
pp. eabg3055 ◽  
Author(s):  
Nicholas G. Davies ◽  
Sam Abbott ◽  
Rosanna C. Barnard ◽  
Christopher I. Jarvis ◽  
Adam J. Kucharski ◽  
...  
Keyword(s):  
United States ◽  
Severe Acute Respiratory Syndrome ◽  
Reproduction Number ◽  
The United States ◽  
Control Measures ◽  
Transmission Model ◽  
Educational Institutions ◽  
Stringent Control ◽  
Dynamic Transmission Model ◽  
Credible Intervals

A severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, VOC 202012/01 (lineage B.1.1.7), emerged in southeast England in September 2020 and is rapidly spreading toward fixation. Using a variety of statistical and dynamic modeling approaches, we estimate that this variant has a 43 to 90% (range of 95% credible intervals, 38 to 130%) higher reproduction number than preexisting variants. A fitted two-strain dynamic transmission model shows that VOC 202012/01 will lead to large resurgences of COVID-19 cases. Without stringent control measures, including limited closure of educational institutions and a greatly accelerated vaccine rollout, COVID-19 hospitalizations and deaths across England in the first 6 months of 2021 were projected to exceed those in 2020. VOC 202012/01 has spread globally and exhibits a similar transmission increase (59 to 74%) in Denmark, Switzerland, and the United States.

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