scholarly journals ESTIMATION OF THE VALUE OF THE COVID-19 BASIC REPRODUCTIVE NUMBER AND THE EFFECT OF ANTI-EPIDEMIC MEASURES AND “SEASONAL FACTOR” ON THIS VALUE

2021 ◽  
Vol 18 (38) ◽  
pp. 149-163
Author(s):  
Andrey GERASIMOV ◽  
Irina SEMENYCHEVA ◽  
Olga BELAIA ◽  
Elena VOLCHKOVA ◽  
Andrey GOROBCHENKO
Keyword(s):  
Accurate Method ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Reproduction Rate ◽  
Infected People ◽  
Noticeable Increase ◽  
A Value ◽  
Health Authorities ◽  
Seasonal Factors ◽  
Seasonal Factor

Background: The emergence of COVID-19 has led to increased attention to mathematical models of epidemiology, one of the main parameters of which is the basic reproductive number R0. Its value determines both the dynamics of the incidence and the level of anti-epidemic measures. Therefore, it is desirable to have a fairly accurate method for assessing R0 for each day. Aim: Develop a methodology for determining the R0 value for COVID-19, taking into account a reasonably rapid and significant change in its value over time. Methods: a method for calculating reproduction number R0 was proposed for assessing COVID-19 R0, taking into account the change in the contagiousness of the infected people during the infectious process. Results and Discussion: In Russia in June-August 2020, the reproduction rate was slightly less 1, but in September R0 began to grow, exceeded 1, which was caused a noticeable increase in the incidence. During June in Brazil, R0 stabilized at a value of 1. The activity of transmission of the pathogen is influenced by seasonal changes in the reproduction rate R0 and the level of community immune status. Based on the assessment of the dynamics of the incidence of other pneumonia, it was found that the change of R0 during the year is about 10%, with a minimum in summer. Conclusions: while maintaining the current activity of anti-epidemic measures due to seasonal factors of the activity of the transmission mechanism and accumulation of the immune individuals in the coming months, the situation in the Russian Federation will worsen with an increase in the incidence doubled within six months, and in Brazil in six months — improve with a decrease in the incidence ten times. However, the dynamics of the incidence will be determined primarily by the work of the administration and health authorities and the conscientiousness of citizens.

scholarly journals Relating the Progeny Production Curve to the Speed of an Epidemic

2013 ◽  
Vol 103 (3) ◽  
pp. 204-215 ◽  
Author(s):  
Francis J. Ferrandino
Keyword(s):  
Theoretical Models ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Progeny Production ◽  
A Value ◽  
Order Expansion ◽  
Mckendrick Equation ◽  
Temporal Moments ◽  
Production Curve ◽  
Mean Time

The dependence of the initial infection rate, r, on the basic reproductive number, R0, and the temporal moments of the progeny production curve are examined. A solution to the linearized Kermack-McKendrick equation is presented and used to analyze a variety of theoretical models of pathogen reproduction. The solution yields a relation between r and the basic reproductive number, R0; the mean time between pathogen generations, μ; and the standard deviation about this mean, σ. A transformation using the dimensionless variables rμ and rσ is introduced, which maps the solution onto a one-dimensional curve. An approximation for the value of r in terms of R0 and the first four temporal moments of the reproductive curve is derived. This allows direct comparison of epidemics resulting from theoretical models with those generated using experimentally obtained reproduction curves. For epidemics characterized by a value of rμ < 5, the value of r is well determined (<2%) by this fourth-order expansion regardless of the functional form of the reproduction curve.

scholarly journals Characteristics and evaluation of the effectiveness of monitoring and control measures for the first 69 Patients with COVID-19 from 18 January 2020 to 2 March in Wuxi, China

2020 ◽  
Author(s):  
Ping Shi ◽  
Yumeng Gao ◽  
Yuan Shen ◽  
Enping Chen ◽  
Hai Chen ◽  
...  
Keyword(s):  
Risk Factors ◽  
Close Contact ◽  
Virus Detection ◽  
Control Measures ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Monitoring And Control ◽  
Infected People ◽  
Novel Coronavirus ◽  
And Control

Abstract Background: The novel coronavirus disease 2019(COVID-19) outbreak and has caused has caused 82,830 confirmed cases and 4,633 deaths in China by 26 April 2020. We analyzed data on 69 infections in Wuxi to describe the epidemiologic characteristics and evaluate the control measures.Methods: The demographic characteristics, exposure history, and illness timelines of COVID-19 cases in Wuxi were collected.Results: Among the 69 positive infections with COVID-19, mild and normal types accounted for 75.36% (52/69), adolescents and children are mainly mild and asymptomatic. The basic reproductive number was estimated to be 1.12 (95% CI, 0.71 to 1.69). The mean incubation period was estimated to be 4.77 days (95% CI, 3.61 to 5.94), with a mean serial interval of 6.31 days (95%CI, 5.12 to 7.50). We also found that age (RR=1.57, 95%CI: 1.11-2.21) and fever (RR=4.09, 95%CI: 1.10-15.19) were risk factors for COVID-19 disease severity.Conclusions: The incidence of COVID-19 in Wuxi has turned into a lower level, suggesting that the early prevention and control measures have achieved effectiveness. The community transmission can be effectively prevented through isolation and virus detection of all the people who were exposed together and close contact with the infected people. Aging and fever are risk factors for clinical outcome, which might be useful for preventing severe transition.

scholarly journals Early Spatiotemporal Patterns and Population Characteristics of the COVID-19 Pandemic in Southeast Asia

Healthcare ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1220
Author(s):  
Mingjian Zhu ◽  
Jirapat Kleepbua ◽  
Zhou Guan ◽  
Sien Ping Chew ◽  
Joanna Weihui Tan ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Population Characteristics ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Country Level ◽  
Disease Patterns ◽  
Geographical Variations ◽  
Health Authorities ◽  
Efficient Resource ◽  
Exponential Regression Model

This observational study aims to investigate the early disease patterns of coronavirus disease 2019 (COVID-19) in Southeast Asia, consequently providing historical experience for further interventions. Data were extracted from official websites of the WHO and health authorities of relevant countries. A total of 1346 confirmed cases of COVID-19, with 217 recoveries and 18 deaths, were reported in Southeast Asia as of 16 March 2020. The basic reproductive number (R0) of COVID-19 in the region was estimated as 2.51 (95% CI:2.31 to 2.73), and there were significant geographical variations at the subregional level. Early transmission dynamics were examined with an exponential regression model: y = 0.30e0.13x (p < 0.01, R2 = 0.96), which could help predict short-term incidence. Country-level disease burden was positively correlated with Human Development Index (r = 0.86, p < 0.01). A potential early shift in spatial diffusion patterns and a spatiotemporal cluster occurring in Malaysia and Singapore were detected. Demographic analyses of 925 confirmed cases indicated a median age of 44 years and a sex ratio (male/female) of 1.25. Age may play a significant role in both susceptibilities and outcomes. The COVID-19 situation in Southeast Asia is challenging and unevenly geographically distributed. Hence, enhanced real-time surveillance and more efficient resource allocation are urgently needed.

scholarly journals Epidemic Dynamics of COVID-19 Based on SEAIUHR Model Considering Asymptomatic Cases in Henan Province, China

2020 ◽  
Author(s):  
Chunyu Li ◽  
Yuchen Zhu ◽  
Chang Qi ◽  
Lili Liu ◽  
Dandan Zhang ◽  
...  
Keyword(s):  
Early Stage ◽  
Henan Province ◽  
Control Measures ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Infected People ◽  
Epidemic Dynamics ◽  
Global Pandemic ◽  
Prevention And Control Measures ◽  
Novel Coronavirus

Abstract Background New coronavirus disease (COVID-19), an infectious disease caused by a type of novel coronavirus, has emerged in various countries since the end of 2019 and caused a global pandemic. Many infected people went undetected because their symptoms were mild or asymptomatic, but the proportion and infectivity of asymptomatic infections remained unknown. Therefore, in this paper, we analyzed the proportion and infectivity of asymptomatic cases, as we as the prevalence of COVID-19 in Henan province. Methods We constructed SEAIUHR model based on COVID-19 cases reported from 21 January to 26 February 2020 in Henan province to estimate the proportion and infectivity of asymptomatic cases, as we as the change of effective reproductive number, \({R}_{t}\). At the same time, we simulated the changes of cases in different scenarios by changing the time and intensity of the implementation of prevention and control measures. Results The proportion of asymptomatic cases among COVID-19 infected individuals was 42% and infectivity of asymptomatic cases was 10% of that symptomatic ones. The basic reproductive number\({R}_{0}\)=2.73, and \({R}_{t}\) dropped below 1 on 1 February under a series of measures. If measures were taken five days earlier, the number of cases would be reduced by 2/3, and after 5 days the number would more than triple. Conclusions In Henan Province, the COVID-19 epidemic spread rapidly in the early stage, and there were a large number of asymptomatic infected individuals with relatively low infectivity. However, the epidemic was quickly brought under control with national measures, and the earlier measures were implemented, the better.

scholarly journals Modeling the dengue fever transmission in a periodic environment

2021 ◽  
Vol 55 (1) ◽  
pp. 71-107
Author(s):  
Julián Alejandro Olarte ◽  
Anibal Muñoz
Keyword(s):  
Dengue Fever ◽  
Vertical Transmission ◽  
Ecological Factors ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Infected People ◽  
Periodic Environment ◽  
Threshold Conditions ◽  
Definition Of ◽  
Disease Free

A mathematical model for dengue fever transmission is analyzed, which incorporates relevant biological and ecological factors: vertical transmission and seasonality in the interaction between the vector (Aedes aegypti females) and the host (human). The existence and uniqueness of a positive disease-free periodic solution is proved; the global stability of the disease-free solution and the effect of periodic migrations of mosquitoes carrying the virus on the transmission of dengue are analyzed utilizing the mathematical definition of the Basic Reproductive Number in periodic environments; finally, it is numerically corroborated with the help of the Basic Reproductive Number that dengue cannot invade the disease-free state if it is less than one and can invade if it is greater than one, however, in both threshold conditions when vertical transmission occurs, the number of infected people and carrier vectors rises, representing a mechanism for the persistence of dengue cases in a community throughout a natural year.

scholarly journals The epidemiology and transmissibility of Zika virus in Girardot and San Andres island, Colombia, September 2015 to January 2016

2016 ◽  
Vol 21 (28) ◽  
Author(s):  
Diana Patricia Rojas ◽  
Natalie E Dean ◽  
Yang Yang ◽  
Eben Kenah ◽  
Juliana Quintero ◽  
...  
Keyword(s):  
Zika Virus ◽  
Virus Disease ◽  
Age Groups ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Incidence Data ◽  
Health Authorities ◽  
Rapid Spread ◽  
Polymerase Chain ◽  
San Andres

Transmission of Zika virus (ZIKV) was first detected in Colombia in September 2015. As of April 2016, Colombia had reported over 65,000 cases of Zika virus disease (ZVD). We analysed daily surveillance data of ZVD cases reported to the health authorities of San Andres and Girardot, Colombia, between September 2015 and January 2016. ZVD was laboratory-confirmed by reverse transcription-polymerase chain reaction (RT-PCR) in the serum of acute cases within five days of symptom onset. We use daily incidence data to estimate the basic reproductive number (R0) in each population. We identified 928 and 1,936 reported ZVD cases from San Andres and Girardot, respectively. The overall attack rate for reported ZVD was 12.13 cases per 1,000 residents of San Andres and 18.43 cases per 1,000 residents of Girardot. Attack rates were significantly higher in females in both municipalities (p < 0.001). Cases occurred in all age groups with highest rates in 20 to 49 year-olds. The estimated R0 for the Zika outbreak was 1.41 (95% confidence interval (CI): 1.15–1.74) in San Andres and 4.61 (95% CI: 4.11–5.16) in Girardot. Transmission of ZIKV is ongoing in the Americas. The estimated R0 from Colombia supports the observed rapid spread.

scholarly journals Dynamics analysis of an online gambling spreading model on scale-free networks

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Yu Kong ◽  
Tao Li ◽  
Yuanmei Wang ◽  
Xinming Cheng ◽  
He Wang ◽  
...  
Keyword(s):  
Network Topology ◽  
Negative Impact ◽  
Online Gambling ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Scale Free ◽  
Spreading Model ◽  
Spreading Dynamics ◽  
Scale Free Networks ◽  
Gambling Policy

AbstractNowadays, online gambling has a great negative impact on the society. In order to study the effect of people’s psychological factors, anti-gambling policy, and social network topology on online gambling dynamics, a new SHGD (susceptible–hesitator–gambler–disclaimer) online gambling spreading model is proposed on scale-free networks. The spreading dynamics of online gambling is studied. The basic reproductive number $R_{0}$ R 0 is got and analyzed. The basic reproductive number $R_{0}$ R 0 is related to anti-gambling policy and the network topology. Then, gambling-free equilibrium $E_{0}$ E 0 and gambling-prevailing equilibrium $E_{ +} $ E + are obtained. The global stability of $E_{0}$ E 0 is analyzed. The global attractivity of $E_{ +} $ E + and the persistence of online gambling phenomenon are studied. Finally, the theoretical results are verified by some simulations.

scholarly journals Effects of social distancing on the spreading of COVID-19 inferred from mobile phone data

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hamid Khataee ◽  
Istvan Scheuring ◽  
Andras Czirok ◽  
Zoltan Neufeld
Keyword(s):  
Mobile Phone ◽  
Basic Reproductive Number ◽  
Mobile Phone Data ◽  
Reproductive Number ◽  
Expansion Phase ◽  
Social Distancing ◽  
Exponential Expansion ◽  
Total Death ◽  
Mobility Reduction ◽  
Epidemiological Parameters

AbstractA better understanding of how the COVID-19 pandemic responds to social distancing efforts is required for the control of future outbreaks and to calibrate partial lock-downs. We present quantitative relationships between key parameters characterizing the COVID-19 epidemiology and social distancing efforts of nine selected European countries. Epidemiological parameters were extracted from the number of daily deaths data, while mitigation efforts are estimated from mobile phone tracking data. The decrease of the basic reproductive number ($$R_0$$ R 0 ) as well as the duration of the initial exponential expansion phase of the epidemic strongly correlates with the magnitude of mobility reduction. Utilizing these relationships we decipher the relative impact of the timing and the extent of social distancing on the total death burden of the pandemic.

scholarly journals Huanglongbing Model under the Control Strategy of Discontinuous Removal of Infected Trees

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1164
Author(s):  
Weiwei Ling ◽  
Pinxia Wu ◽  
Xiumei Li ◽  
Liangjin Xie
Keyword(s):  
Infectious Disease ◽  
Global Stability ◽  
Control Strategy ◽  
Theoretical Basis ◽  
Dynamic Properties ◽  
Transmission Mechanism ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Vector Borne ◽  
Citrus Trees

By using differential equations with discontinuous right-hand sides, a dynamic model for vector-borne infectious disease under the discontinuous removal of infected trees was established after understanding the transmission mechanism of Huanglongbing (HLB) disease in citrus trees. Through calculation, the basic reproductive number of the model can be attained and the properties of the model are discussed. On this basis, the existence and global stability of the calculated equilibria are verified. Moreover, it was found that different I0 in the control strategy cannot change the dynamic properties of HLB disease. However, the lower the value of I0, the fewer HLB-infected citrus trees, which provides a theoretical basis for controlling HLB disease and reducing expenditure.

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