Overview

MeSH Disease

Disease (59)

Infections (48)

Death (35)

Human Phenotype

Pneumonia (5)

Falls (4)

Fever (3)

Cough (2)

Anxiety (2)

Transmission

Seroprevalence
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The effect of public health policies in the transmission TRANS of COVID-19 for South American countries

Authors: Bryan Valcarcel; Jose L Avilez; J. Smith Torres-Roman; Julio A Poterico; Janina Bazalar-Palacios; Carlo La Vecchia

doi:10.1101/2020.08.09.20149286 Date: 2020-08-12 Source: medRxiv

Objectives: The analysis of transmission TRANS dynamics is crucial to determine whether mitigation or suppression measures reduce the spread of Coronavirus disease MESHD 2019 (COVID-19). This study sought to estimate the basic ( R0 TRANS) and time-dependent (Rt) reproduction number TRANS of COVID-19 and contrast the public health measures for ten South American countries. Methods: Data was obtained from the European Centre for Disease MESHD Prevention and Control. Country-specific R0 TRANS estimates during the first two weeks of the outbreak and Rt estimates after 90 days were estimated. Results: Countries used a combination of isolation, social distancing, quarantine, and community-wide containment measures to contain the spread of COVID-19 at different points in time. R0 TRANS ranged from 1.52 (95% confidence interval: 1.13-1.99) in Venezuela, to 3.83 (3.04-4.75) in Chile, whereas Rt, after 90 days, ranged from 0.71 (95% credible interval: 0.39-1.05) in Uruguay to 1.20 (1.19-1.20) in Brazil. Different R0 TRANS and Rt values may be related to the testing capacity of each country. Conclusion: R0 TRANS in the early phase of the outbreak varied across the South American countries. The adopted public health measures in the initial period of the pandemic appear to have reduced Rt over time in each country.

The impact of non-pharmaceutical interventions on SARS-CoV-2 transmission TRANS across 130 countries and territories

Authors: Yang Liu; Christian Morgenstern; James Kelly; Rachel Lowe; - CMMID COVID-19 Working Group; Mark Jit

doi:10.1101/2020.08.11.20172643 Date: 2020-08-12 Source: medRxiv

Introduction: Non-pharmaceutical interventions (NPIs) are used to reduce transmission TRANS of SARS coronavirus 2 (SARS-CoV-2) that causes coronavirus disease MESHD 2019 (COVID-19). However, empirical evidence of the effectiveness of specific NPIs has been inconsistent. We assessed the effectiveness of NPIs around internal containment and closure, international travel TRANS restrictions, economic measures, and health system actions on SARS-CoV-2 transmission TRANS in 130 countries and territories. Methods: We used panel (longitudinal) regression to estimate the effectiveness of 13 categories of NPIs in reducing SARS-CoV-2 transmission TRANS with data from January - June 2020. First, we examined the temporal association between NPIs using hierarchical cluster analyses. We then regressed the time-varying reproduction number TRANS (Rt) of COVID-19 against different NPIs. We examined different model specifications to account for the temporal lag between NPIs and changes in Rt, levels of NPI intensity, time-varying changes in NPI effect and variable selection criteria. Results were interpreted taking into account both the range of model specifications and temporal clustering of NPIs. Results: There was strong evidence for an association between two NPIs (school closure, internal movement restrictions) and reduced Rt. Another three NPIs (workplace closure, income support and debt/contract relief) had strong evidence of effectiveness when ignoring their level of intensity, while two NPIs (public events cancellation, restriction on gatherings) had strong evidence of their effectiveness only when evaluating their implementation at maximum capacity (e.g., restrictions on 1000+ people gathering were not effective, restrictions on <10 people gathering was). Evidence supporting the effectiveness of the remaining NPIs (stay-at-home requirements, public information campaigns, public transport closure, international travel TRANS controls, testing, contact tracing TRANS) was inconsistent and inconclusive. We found temporal clustering between many of the NPIs. Conclusion: Understanding the impact that specific NPIs have had on SARS-CoV-2 transmission TRANS is complicated by temporal clustering, time-dependent variation in effects and differences in NPI intensity. However, the effectiveness of school closure and internal movement restrictions appears robust across different model specifications taking into account these effects, with some evidence that other NPIs may also be effective under particular conditions. This provides empirical evidence for the potential effectiveness of many although not all the actions policy-makers are taking to respond to the COVID-19 pandemic.

Epidemiological characteristics of SARS-COV-2 in Myanmar

Authors: Aung Min Thway; Htun Tayza; Tun Tun Win; Ye Minn Tun; Moe Myint Aung; Yan Naung Win; Kyaw M Tun

doi:10.1101/2020.08.02.20166504 Date: 2020-08-04 Source: medRxiv

Coronavirus disease MESHD (COVID-19) is an infectious disease MESHD caused by a newly discovered severe acute respiratory syndrome MESHD coronavirus 2 (SARS-CoV-2). In Myanmar, first COVID-19 reported cases were identified on 23rd March 2020. There were 336 reported confirmed cases TRANS, 261 recovered and 6 deaths MESHD through 13th July 2020. The study was a retrospective case series and all COVID-19 confirmed cases TRANS from 23rd March to 13th July 2020 were included. The data series of COVID-19 cases were extracted from the daily official reports of the Ministry of Health and Sports (MOHS), Myanmar and Centers for Disease MESHD Control and Prevention (CDC), Myanmar. Among 336 confirmed cases TRANS, there were 169 cases with reported transmission TRANS events. The median serial interval TRANS was 4 days (IQR 3, 2-5) with the range of 0 - 26 days. The mean of the reproduction number TRANS was 1.44 with (95% CI = 1.30-1.60) by exponential growth method and 1.32 with (95% CI = 0.98-1.73) confident interval by maximum likelihood method. This study outlined the epidemiological characteristics and epidemic parameters of COVID-19 in Myanmar. The estimation parameters in this study can be comparable with other studies and variability of these parameters can be considered when implementing disease MESHD control strategy in Myanmar.

Analysis of COVID-19 and comorbidity co- infection MESHD Model with Optimal Control

Authors: Dr. Andrew Omame; Nometa Ikenna

doi:10.1101/2020.08.04.20168013 Date: 2020-08-04 Source: medRxiv

The new coronavirus disease MESHD 2019 (COVID-19) infection MESHD is a double challenge for people infected with comorbidities such as cardiovascular and cerebrovascular diseases MESHD and diabetes. Comorbidities have been reported to be risk factors for the complications of COVID-19. In this work, we develop and analyze a mathematical model for the dynamics of COVID-19 infection MESHD in order to assess the impacts of prior comorbidity on COVID-19 complications and COVID-19 re- infection MESHD. The model is simulated using data relevant to the dynamics of the diseases MESHD in Lagos, Nigeria, making predictions for the attainment of peak periods in the presence or absence of comorbidity. The model is shown to undergo the phenomenon of backward bifurcation caused by the parameter accounting for increased susceptibility to COVID-19 infection MESHD by comorbid susceptibles as well as the rate of re- infection MESHD by those who have recovered from a previous COVID-19 infection MESHD. Sensitivity SERO analysis of the model when the population of individuals co-infected with COVID-19 and comorbidity is used as response function revealed that the top ranked parameters that drive the dynamics of the co- infection MESHD model are the effective contact rate for COVID-19 transmission TRANS, $\beta\sst{cv}$, the parameter accounting for increased susceptibility to COVID-19 by comorbid susceptibles, $\chi\sst{cm}$, the comorbidity development rate, $\theta\sst{cm}$, the detection rate for singly infected and co-infected individuals, $\eta_1$ and $\eta_2$, as well as the recovery rate from COVID-19 for co-infected individuals, $\varphi\sst{i2}$. Simulations of the model reveal that the cumulative confirmed cases TRANS (without comorbidity) may get up to 180,000 after 200 days, if the hyper susceptibility rate of comorbid susceptibles is as high as 1.2 per day. Also, the cumulative confirmed cases TRANS (including those co-infected with comorbidity) may be as high as 1000,000 cases by the end of November, 2020 if the re- infection MESHD rates for COVID-19 is 0.1 per day. It may be worse than this if the re- infection MESHD rates increase higher. Moreover, if policies are strictly put in place to step down the probability of COVID-19 infection MESHD by comorbid susceptibles to as low as 0.4 per day and step up the detection rate for singly infected individuals to 0.7 per day, then the reproduction number TRANS can be brought very low below one, and COVID-19 infection MESHD eliminated from the population. In addition, optimal control and cost-effectiveness analysis of the model reveal that the the strategy that prevents COVID-19 infection MESHD by comorbid susceptibles has the least ICER and is the most cost-effective of all the control strategies for the prevention of COVID-19.

Mathematical modeling of the transmission TRANS of SARS-CoV-2 '' Evaluating the impact of isolation in Sao Paulo State (Brazil) and lockdown in Spain associated with protective measures on the epidemic of covid-19

Authors: Hyun Mo Yang; Luis Pedro Lombardi Jr.; Fabio Fernandes Morato Castro; Ariana Campos Yang

doi:10.1101/2020.07.30.20165191 Date: 2020-08-01 Source: medRxiv

Coronavirus disease MESHD 2019 (covid-19), with the fatality rate in elder (60 years old or more) being much higher than young (60 years old or less) patients, was declared a pandemic by the World Health Organization on March 11, 2020. Taking into account this age TRANS-dependent fatality rate, a mathematical model considering young and elder subpopulations was formulated based on the natural history of covid-19 to study the transmission TRANS of the SARS-CoV-2. This model can be applied to study the epidemiological scenario resulting from the adoption of isolation or lockdown in many countries to control the rapid propagation of covid-19. We chose as examples the isolation adopted in Sao Paulo State (Brazil) in the early phase but not at the beginning of the epidemic, and the lockdown implemented in Spain when the number of severe covid-19 cases was increasing rapidly. Based on the data collected from Sa o Paulo State and Spain, the model parameters were evaluated and we obtained higher estimation for the basic reproduction number TRANS R0 TRANS (9.24 for Sao Paulo State, and 8 for Spain) compared to the currently accepted estimation of R0 TRANS around 3. The model allowed to explain the flattening of the epidemic curves by isolation in Sao Paulo State and lockdown in Spain when associated with the protective measures (face mask and social distancing) adopted by the population. However, a simplified mathematical model providing lower estimation for R0 TRANS did not explain the flattening of the epidemic curves. The implementation of the isolation in Sa o Paulo State before the rapidly increasing phase of the epidemic enlarged the period of the first wave of the epidemic and delayed its peak, which are the desirable results of isolation to avoid the overloading in the health care system.

Isolation Considered Epidemiological Model for the Prediction of COVID-19 Trend in Tokyo, Japan

Authors: Motoaki Utamura; Makoto Koizumi; Seiichi Kirikami

doi:10.1101/2020.07.31.20165829 Date: 2020-07-31 Source: medRxiv

Background: Coronavirus Disease MESHD 2019 (COVID19) currently poses a global public health threat. Although no exception, Tokyo, Japan was affected at first by only a small epidemic. Medical collapse nevertheless nearly happened because no predictive method existed for counting patients. A standard SIR epidemiological model and its derivatives predict susceptible, infectious, and removed (recovered/ deaths MESHD) cases but ignore isolation of confirmed cases TRANS. Predicting COVID19 trends with hospitalized and infectious people in field separately is important to prepare beds and develop quarantine strategies. Methods: Time-series COVID19 data from February 28 to May 23, 2020 in Tokyo were adopted for this study. A novel epidemiological model based on delay differential equation was proposed. The model can evaluate patients in hospitals and infectious cases in the field. Various data such as daily new cases, cumulative infections MESHD, patients in hospital, and PCR test positivity ratios were used to examine the model. This approach derived an alternative formulation equivalent to the standard SIR model. Its results were compared quantitatively with those of the present isolation model. Results: The basic reproductive number TRANS, inferred as 2.30, is a dimensionless parameter composed of modeling parameters. Effects of intervention to mitigate the epidemic spread were assessed a posteriori. An exit policy of how and when to release a statement of emergency MESHD was also assessed using the model. Furthermore, results suggest that the rapid isolation of infectious cases has a large potential to effectively mitigate the spread of infection MESHD and restores social and economic activities safely. Conclusions: A novel mathematical model was proposed and examined using COVID19 data for Tokyo. Results show that shortening the period from infection MESHD to hospitalization is effective against outbreak without rigorous public health intervention and control. Faster and precise case cluster detection and wider and quicker introduction of testing measures are strongly recommended.

The effective reproductive number TRANS (Rt) of COVID-19 and its relationship with social distancing

Authors: Lucas Jardim Sr.; Jose Alexandre Diniz-Filho Sr.; Thiago Fernando Rangel Sr.; Cristiana Maria Toscano II

doi:10.1101/2020.07.28.20163493 Date: 2020-07-29 Source: medRxiv

The expansion of the new coronavirus disease MESHD (COVID-19) triggered a renewed public interest in epidemiological models and on how parameters can be estimated from observed data. Here we investigated the relationship between average number of transmissions TRANS though time, the reproductive number TRANS Rt, and social distancing index as reported by mobile phone data service inloco, for Goias State, Brazil, between March and June 2020. We calculated Rt values using EpiEstim package in R-plataform for confirmed cases TRANS incidence curves. We found a correlation equal to -0.72 between Rt values for confirmed cases TRANS and isolation index at a time lag of 8 days. As the Rt values were paired with center of the moving window of 7 days, the delay matches the mean incubation period TRANS of the virus. Our findings reinforce that isolation index can be an effective surrogate for modeling and epidemiological analyses and, more importantly, can be an useful metrics for anticipating the need for early interventions, a critical issue in public health.

Epidemic response to physical distancing policies and their impact on the outbreak risk

Authors: Fabio Vanni; David Lambert; Luigi Palatella

id:2007.14620v2 Date: 2020-07-29 Source: arXiv

We introduce a theoretical framework that highlights the impact of physical distancing variables such as human mobility and physical proximity on the evolution of epidemics and, crucially, on the reproduction number TRANS. In particular, in response to the coronavirus disease MESHD (CoViD-19) pandemic, countries have introduced various levels of 'lockdown' to reduce the number of new infections MESHD. Specifically we use a collisional approach to an infection MESHD- age TRANS structured model described by a renewal equation for the time homogeneous evolution of epidemics. As a result, we show how various contributions of the lockdown policies, namely physical proximity and human mobility, reduce the impact of SARS-CoV-2 and mitigate the risk of disease MESHD resurgence. We check our theoretical framework using real-world data on physical distancing with two different data repositories, obtaining consistent results. Finally, we propose an equation for the effective reproduction number TRANS which takes into account types of interactions among people, which may help policy makers to improve remote-working organizational structure.

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

Authors: Chunyu Li; Yuchen Zhu; Chang Qi; Lili Liu; Dandan Zhang; Xu Wang; Kaili She; Yan Jia; Tingxuan Liu; Momiao Xiong; Xiujun Li

doi:10.21203/rs.3.rs-50050/v1 Date: 2020-07-28 Source: ResearchSquare

Background New coronavirus disease MESHD (COVID-19), an infectious disease MESHD 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 TRANS, but the proportion and infectivity of asymptomatic infections MESHD asymptomatic TRANS remained unknown. Therefore, in this paper, we analyzed the proportion and infectivity of asymptomatic TRANS cases, as we as the prevalence SERO 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 TRANS cases, as we as the change of effective reproductive number TRANS, $${R}_{t}$$. 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 TRANS cases among COVID-19 infected individuals was 42% and infectivity of asymptomatic TRANS cases was 10% of that symptomatic ones. The basic reproductive number$${R TRANS}_{0}$$=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 TRANS 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.

INDEPENDENT ASSOCIATION OF METEOROLOGICAL CHARACTERISTICS WITH INITIAL SPREAD OF COVID-19 IN INDIA

Authors: Hemant Kulkarni; Harshwardhan Vinod Khandait; Uday Wasudeorao Narlawar; Pragati G Rathod; Manju Mamtani

doi:10.1101/2020.07.20.20157784 Date: 2020-07-26 Source: medRxiv

Whether weather plays a part in the transmissibility TRANS of the novel COronaVIrus Disease MESHD-19 (COVID-19) is still not established. We tested the hypothesis that meteorological factors (air temperature, relative humidity, air pressure, wind speed and rainfall) are independently associated with transmissibility TRANS of COVID-19 quantified using the basic reproduction rate ( R0 TRANS). We used publicly available datasets on daily COVID-19 case counts (total n = 108,308), three-hourly meteorological data and community mobility data over a three-month period. Estimated R0 TRANS varied between 1.15-1.28. Mean daily air temperature (inversely) and wind speed (positively) were significantly associated with time dependent R0 TRANS, but the contribution of countrywide lockdown to variability in R0 TRANS was over three times stronger as compared to that of temperature and wind speed combined. Thus, abating temperatures and easing lockdown may concur with increased transmissibility TRANS of COVID-19.

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 All None MeSH Disease Human Phenotype Transmission Seroprevalence

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