scholarly journals The Estimated Time-Varying Reproduction Numbers during the Ongoing Epidemic of the Coronavirus Disease 2019 (COVID-19) in China

2020 ◽  
Author(s):  
Fu-Chang Hu ◽  
Fang-Yu Wen
Keyword(s):  
Infectious Disease ◽  
Reproduction Number ◽  
Control Measures ◽  
Time Varying ◽  
Epidemic Curve ◽  
Health Authorities ◽  
Reproduction Numbers ◽  
Public Health Authorities ◽  
Control And Prevention ◽  
Over Time

AbstractBackgroundHow could we anticipate the progression of the ongoing epidemic of the coronavirus disease 2019 (COVID-19) in China? As a measure of transmissibility, the value of basic reproduction number varies over time during an epidemic of infectious disease. Hence, this study aimed to estimate concurrently the time-varying reproduction number over time during the COVID-19 epidemic in China.MethodsWe extracted the epidemic data from the “Tracking the Epidemic” website of the Chinese Center for Disease Control and Prevention for the duration of January 19, 2020 and March 14, 2020. Then, we applied the novel method implemented in the incidence and EpiEstim packages to the data of daily new confirmed cases for robustly estimating the time-varying reproduction number in the R software.ResultsThe epidemic curve of daily new confirmed cases in China peaked around February 4−6, 2020, and then declined gradually, except the very high peak on February 12, 2020 owing to the added clinically diagnosed cases (Hubei Province only). Under two specified plausible scenarios for the distribution of serial interval, both curves of the estimated time-varying reproduction numbers fell below 1.0 around February 17−18, 2020. Finally, the COVID-19 epidemic in China abated around March 7−8, 2020, indicating that the prompt and aggressive control measures of China were effective.ConclusionSeeing the estimated time-varying reproduction number going downhill was more informative than looking for the drops in the daily number of new confirmed cases during an ongoing epidemic of infectious disease. We urged public health authorities and scientists to estimate time-varying reproduction numbers routinely during epidemics of infectious diseases and to report them daily to the public until the end of the COVID-19 epidemic.

scholarly journals Modelling the Effectiveness of Epidemic Control Measures in Preventing the Transmission of COVID-19 in Malaysia

2020 ◽  
Vol 17 (15) ◽  
pp. 5509 ◽  
Author(s):  
Balvinder Singh Gill ◽  
Vivek Jason Jayaraj ◽  
Sarbhan Singh ◽  
Sumarni Mohd Ghazali ◽  
Yoon Ling Cheong ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Model Calibration ◽  
Reproduction Number ◽  
Close Contact ◽  
Movement Control ◽  
Control Measures ◽  
Seir Model ◽  
Epidemic Curve ◽  
Reproduction Numbers ◽  
Control Order

Malaysia is currently facing an outbreak of COVID-19. We aim to present the first study in Malaysia to report the reproduction numbers and develop a mathematical model forecasting COVID-19 transmission by including isolation, quarantine, and movement control measures. We utilized a susceptible, exposed, infectious, and recovered (SEIR) model by incorporating isolation, quarantine, and movement control order (MCO) taken in Malaysia. The simulations were fitted into the Malaysian COVID-19 active case numbers, allowing approximation of parameters consisting of probability of transmission per contact (β), average number of contacts per day per case (ζ), and proportion of close-contact traced per day (q). The effective reproduction number (Rt) was also determined through this model. Our model calibration estimated that (β), (ζ), and (q) were 0.052, 25 persons, and 0.23, respectively. The (Rt) was estimated to be 1.68. MCO measures reduce the peak number of active COVID-19 cases by 99.1% and reduce (ζ) from 25 (pre-MCO) to 7 (during MCO). The flattening of the epidemic curve was also observed with the implementation of these control measures. We conclude that isolation, quarantine, and MCO measures are essential to break the transmission of COVID-19 in Malaysia.

scholarly journals Simulating the progression of the COVID-19 disease in Cameroon using SIR models

2020 ◽  
Author(s):  
Ulrich KAMGUEM NGUEMDJO ◽  
Freeman MENO ◽  
Audric DONGFACK ◽  
Bruno VENTELOU
Keyword(s):  
Public Health ◽  
Basic Reproduction Number ◽  
Reproduction Number ◽  
Sir Model ◽  
Health Policies ◽  
Public Health Policies ◽  
Epidemic Curve ◽  
Health Authorities ◽  
Public Health Authorities ◽  
The Basic Reproduction Number

This paper analyses the evolution of COVID 19 disease in Cameroon over the period March 6 April 2020 using SIR model. Specifically, 1) we evaluate the basic reproduction number of the virus. 2) Determine the peak of the infection and the spread-out period of the disease. 3) Simulate the interventions of public health authorities. Data used in this study is obtained from the Ministry of Health of Cameroon. The results suggest that over the period, the reproduction number of the COVID 19 in Cameroon is about 1.5 and the peak of the infection could occur at the end of May 2020 with about 7.7% of the population infected. Besides, implementation of efficient public health policies could help flattens the epidemic curve.

scholarly journals Estimated Dissemination Ratio—A Practical Alternative to the Reproduction Number for Infectious Diseases

2021 ◽  
Vol 9 ◽  
Author(s):  
Francisco J. Pérez-Reche ◽  
Nick Taylor ◽  
Chris McGuigan ◽  
Philip Conaglen ◽  
Ken J. Forbes ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Infectious Diseases ◽  
Real Time ◽  
Early Warning ◽  
Reproduction Number ◽  
Transmission Rate ◽  
Control Measures ◽  
Epidemic Curve ◽  
The Uk ◽  
The Impact

Policymakers require consistent and accessible tools to monitor the progress of an epidemic and the impact of control measures in real time. One such measure is the Estimated Dissemination Ratio (EDR), a straightforward, easily replicable, and robust measure of the trajectory of an outbreak that has been used for many years in the control of infectious disease in livestock. It is simple to calculate and explain. Its calculation and use are discussed below together with examples from the current COVID-19 outbreak in the UK. These applications illustrate that EDR can demonstrate changes in transmission rate before they may be clear from the epidemic curve. Thus, EDR can provide an early warning that an epidemic is resuming growth, allowing earlier intervention. A conceptual comparison between EDR and the commonly used reproduction number is also provided.

COVID-19: Time-Dependent Effective Reproduction Number and Sub-notification Effect Estimation Modeling (Preprint)

2020 ◽  
Author(s):  
Eduardo Atem De Carvalho ◽  
Rogerio Atem De Carvalho
Keyword(s):  
New York ◽  
Reproduction Number ◽  
Moving Average ◽  
Real Data ◽  
Time Dependent ◽  
Initial Value ◽  
Health Authorities ◽  
Reproduction Numbers ◽  
Effect Estimation ◽  
The Impact

BACKGROUND Since the beginning of the COVID-19 pandemic, researchers and health authorities have sought to identify the different parameters that govern their infection and death cycles, in order to be able to make better decisions. In particular, a series of reproduction number estimation models have been presented, with different practical results. OBJECTIVE This article aims to present an effective and efficient model for estimating the Reproduction Number and to discuss the impacts of sub-notification on these calculations. METHODS The concept of Moving Average Method with Initial value (MAMI) is used, as well as a model for Rt, the Reproduction Number, is derived from experimental data. The models are applied to real data and their performance is presented. RESULTS Analyses on Rt and sub-notification effects for Germany, Italy, Sweden, United Kingdom, South Korea, and the State of New York are presented to show the performance of the methods here introduced. CONCLUSIONS We show that, with relatively simple mathematical tools, it is possible to obtain reliable values for time-dependent, incubation period-independent Reproduction Numbers (Rt). We also demonstrate that the impact of sub-notification is relatively low, after the initial phase of the epidemic cycle has passed.

scholarly journals Users’ Beliefs Toward Physical Distancing in Facebook Pages of Public Health Authorities During COVID-19 Pandemic in Early 2020

2021 ◽  
pp. 109019812110144
Author(s):  
Soon Guan Tan ◽  
Aravind Sesagiri Raamkumar ◽  
Hwee Lin Wee
Keyword(s):  
Public Health ◽  
Health Belief Model ◽  
United States Public Health ◽  
Health Belief ◽  
The United States ◽  
Health Authorities ◽  
Public Health Authorities ◽  
Control And Prevention ◽  
Belief Model ◽  
The Health Belief Model

This study aims to describe Facebook users’ beliefs toward physical distancing measures implemented during the Coronavirus disease (COVID-19) pandemic using the key constructs of the health belief model. A combination of rule-based filtering and manual classification methods was used to classify user comments on COVID-19 Facebook posts of three public health authorities: Centers for Disease Control and Prevention of the United States, Public Health England, and Ministry of Health, Singapore. A total of 104,304 comments were analyzed for posts published between 1 January, 2020, and 31 March, 2020, along with COVID-19 cases and deaths count data from the three countries. Findings indicate that the perceived benefits of physical distancing measures ( n = 3,463; 3.3%) was three times higher than perceived barriers ( n = 1,062; 1.0%). Perceived susceptibility to COVID-19 ( n = 2,934; 2.8%) was higher compared with perceived severity ( n = 2,081; 2.0%). Although susceptibility aspects of physical distancing were discussed more often at the start of the year, mentions on the benefits of intervention emerged stronger toward the end of the analysis period, highlighting the shift in beliefs. The health belief model is useful for understanding Facebook users’ beliefs at a basic level, and it provides a scope for further improvement.

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 First report of an outbreak of cerebral coenurosis in Dhofari goats in Oman

2019 ◽  
Vol 28 (3) ◽  
pp. 479-488 ◽  
Author(s):  
Mahmoud Shaban El-Neweshy ◽  
Reda Elbastawisy Khalafalla ◽  
Mohamed Mohamed Sayed Ahmed ◽  
Julanda Hamad Al Mawly ◽  
El-Sayed Mohamed El-Manakhly
Keyword(s):  
Brain Parenchyma ◽  
Control Measures ◽  
Clear Fluid ◽  
Neuronal Necrosis ◽  
Local Public Health ◽  
First Report ◽  
Health Authorities ◽  
Coenurus Cerebralis ◽  
Public Health Authorities ◽  
Cerebral Coenurosis

Abstract This study documented the first outbreak of cerebral coenurosis in goats in Salalah, southern Oman. Deaths of 130 (16.6%) adult native goats in a herd (n=780) were reported from January to June 2017. Affected goats showed various nervous signs ended by death. Investigations for thiamine deficiency, polioencephalomalacia, caprine arthritis encephalitis, and listeriosis were negative. Upon necropsy, multiple (1-4) thin-walled cysts 2-3.5 cm in diameter containing clear fluid with numerous clusters of protoscolices in the cerebrum and cerebellum had replaced the brain parenchyma, causing space-occupying lesions. Parasitologically, the recovered cysts were Coenurus cerebralis, based on the arrangement of protoscolices, and the number and size of their hooks. Morphologically, each protoscolex had four suckers and a rostellum with double-crown hooks. The large and small hooks were 157.7±0.5 µm and 115±0.6 µm in length, respectively. Histopathologically, the parasite destroyed the affected tissues associated with multifocal to diffuse lymphocytic, non-suppurative meningoencephalitis; ischemic neuronal necrosis; and malacia. This is the first report of cerebral coenurosis in livestock in Oman, which should alert the local public health authorities for the application of prevention and control measures.

scholarly journals An interim review of the epidemiological characteristics of 2019 novel coronavirus

2020 ◽  
Vol 42 ◽  
pp. e2020006 ◽  
Author(s):  
Sukhyun Ryu ◽  
Byung Chul Chun
Keyword(s):  
Public Health ◽  
Public Health Emergency ◽  
Control Measures ◽  
Health Authorities ◽  
Public Health Authorities ◽  
Novel Coronavirus ◽  
Epidemiological Characteristics

OBJECTIVES: The 2019 novel coronavirus (2019-nCoV) from Wuhan, China is currently recognized as a public health emergency of global concern.METHODS: We reviewed the currently available literature to provide up-to-date guidance on control measures to be implemented by public health authorities.RESULTS: Some of the epidemiological characteristics of 2019-nCoV have been identified. However, there remain considerable uncertainties, which should be considered when providing guidance to public health authorities on control measures.CONCLUSIONS: Additional studies incorporating more detailed information from confirmed cases would be valuable.

scholarly journals COVID-19 Time-varying Reproduction Numbers Worldwide: An Empirical Analysis of Mandatory and Voluntary Social Distancing

2021 ◽  
Author(s):  
Alexander Chudik ◽  
M. Hashem Pesaran ◽  
Alessandro Rebucci
Keyword(s):  
Reproduction Number ◽  
Transmission Rate ◽  
Economic Incentives ◽  
Moment Condition ◽  
Time Varying ◽  
Linear Interaction ◽  
Susceptible Population ◽  
Social Distancing ◽  
Transmission Rates ◽  
Reproduction Numbers

AbstractThis paper estimates time-varying COVID-19 reproduction numbers worldwide solely based on the number of reported infected cases, allowing for under-reporting. Estimation is based on a moment condition that can be derived from an agent-based stochastic network model of COVID-19 transmission. The outcomes in terms of the reproduction number and the trajectory of per-capita cases through the end of 2020 are very diverse. The reproduction number depends on the transmission rate and the proportion of susceptible population, or the herd immunity effect. Changes in the transmission rate depend on changes in the behavior of the virus, re-flecting mutations and vaccinations, and changes in people’s behavior, reflecting voluntary or government mandated isolation. Over our sample period, neither mutation nor vaccination are major factors, so one can attribute variation in the transmission rate to variations in behavior. Evidence based on panel data models explaining transmission rates for nine European countries indicates that the diversity of outcomes resulted from the non-linear interaction of mandatory containment measures, voluntary precautionary isolation, and the economic incentives that gov-ernments provided to support isolation. These effects are precisely estimated and robust to various assumptions. As a result, countries with seemingly different social distancing policies achieved quite similar outcomes in terms of the reproduction number. These results imply that ignoring the voluntary component of social distancing could introduce an upward bias in the estimates of the effects of lock-downs and support policies on the transmission rates.JEL ClassificationD0, F6, C4, I120, E7

scholarly journals Modelling the evolution of COVID-19 in high-incidence European countries and regions: estimated number of infections and impact of past and future intervention measures

2020 ◽  
Author(s):  
Juan Fernandez-Recio
Keyword(s):  
Reproduction Number ◽  
Mechanistic Model ◽  
Control Measures ◽  
European Countries ◽  
Intervention Measures ◽  
High Incidence ◽  
Long Term Impact ◽  
The Impact ◽  
Over Time

A previously developed mechanistic model of COVID-19 transmission has been adapted and applied here to study the evolution of the disease and the effect of intervention measures in some European countries and territories where the disease had major impact. A clear impact of the major intervention measures on the reproduction number (Rt) has been found in all studied countries and territories, as already suggested by the drop in the number of deaths over time. Interestingly, the impact of such major intervention measures seems to be the same in most of these countries. The model has also provided realistic estimates of the total number of infections, active cases and future outcome. While the predictive capabilities of the model are much more uncertain before the peak of the outbreak, we could still reliably predict the evolution of the disease after a major intervention by assuming the afterwards reproduction number from current study. More challenging is to foresee the long-term impact of softer intervention measures, but this model can estimate the outcome of different scenarios and help planning changes in the implementation of control measures in a given country or region.

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