scholarly journals Tracking progress towards malaria elimination in China: estimates of reproduction numbers and their spatiotemporal variation

2019 ◽  
Author(s):  
Isobel Routledge ◽  
Shengjie Lai ◽  
Katherine E Battle ◽  
Azra C Ghani ◽  
Manuel Gomez-Rodriguez ◽  
...  
Keyword(s):  
Yunnan Province ◽  
Reproduction Number ◽  
Individual Level ◽  
Reproduction Numbers ◽  
Imported Cases ◽  
Geostatistical Models ◽  
Sources Of Infection ◽  
Spatio Temporal ◽  
The Relationship ◽  
Local Transmission

AbstractChina reported zero locally-acquired malaria cases in 2017 and 2018. Understanding the spatio-temporal pattern underlying this decline, especially the relationship between locally-acquired and imported cases, can inform efforts to maintain elimination and prevent re-emergence. This is particularly pertinent in Yunnan province, where the potential for local transmission is highest. Using a geo-located individual-level dataset of cases recorded in Yunnan province between 2011 and 2016, we jointly estimate the case reproduction number, Rc, and the number of unobserved sources of infection. We use these estimates within spatio-temporal geostatistical models to map how transmission varied over time and space, estimate the timeline to elimination and the risk of resurgence. Our estimates suggest that, maintaining current intervention efforts, Yunnan is unlikely to experience sustained local transmission up to 2020. However, even with a mean Rc of 0.005 projected for the year 2019, locally-acquired cases are possible due to high levels of importation.

scholarly journals Transmissibility of coronavirus disease 2019 (COVID-19) in Chinese cities with different transmission dynamics of imported cases

2020 ◽  
Author(s):  
Ka Chun Chong ◽  
Wei Cheng ◽  
Shi Zhao ◽  
Feng Ling ◽  
Kirran N. Mohammad ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Likelihood Function ◽  
Transmission Dynamics ◽  
Time Varying ◽  
Outbreak Response ◽  
Chinese Cities ◽  
Imported Cases ◽  
Response Measures ◽  
Local Transmission

AbstractBackgroundMonitoring the time-varying reproduction number (Rt) of the disease is useful in determining whether there is sustained transmission in a population. In this study, we examined Rt of COVID-19 and compared its transmissibility between different intervention periods in Hangzhou and Shenzhen.MethodsDaily aggregated counts of confirmed imported and local cases between January 1, 2020 and March 13, 2020 were analysed. A likelihood function was constructed to estimate Rt, accounting for imported cases.ResultsAlthough Hangzhou had fewer number of cases than Shenzhen, Shenzhen had higher proportion of imported cases than Hangzhou (83% vs 29%). Since the epidemic of COVID-19 in Shenzhen was dominated by imported cases, Rt was kept below unity through time. On the contrary, Rt was greater than unity in Hangzhou from 16 January to 7 February due to the surge in local cases. Credits to the Wuhan lockdown and outbreak response measures following the local lockdown, Rt decreased steadily and dropped below unity in mid-February.ConclusionThe lockdown measures and local outbreak responses helped reduce the potential of local transmission in Hangzhou and Shenzhen. Meanwhile, cities with similar epidemic trend could have different transmission dynamics given the variation in imported cases.

scholarly journals Estimation of local time-varying reproduction numbers in noisy surveillance data

2021 ◽  
Author(s):  
Wenrui Li ◽  
Katia Bulekova ◽  
Brian Gregor ◽  
Laura F. White ◽  
Eric D. Kolaczyk
Keyword(s):  
Local Time ◽  
Reproduction Number ◽  
Infected Individual ◽  
Accurate Estimation ◽  
Time Varying ◽  
Simulation Studies ◽  
Expected Number ◽  
Reproduction Numbers ◽  
Practical Performance ◽  
Local Transmission

AbstractA valuable metric in understanding infectious disease local dynamics is the local time-varying reproduction number, i.e. the expected number of secondary local cases caused by each infected individual. Accurate estimation of this quantity requires distinguishing cases arising from local transmission from those imported from elsewhere. Realistically, we can expect identification of cases as local or imported to be imperfect. We study the propagation of such errors in estimation of the local time-varying reproduction number. In addition, we propose a Bayesian framework for estimation of the true local time-varying reproduction number when identification errors exist. And we illustrate the practical performance of our estimator through simulation studies and with outbreaks of COVID-19 in Hong Kong and Victoria, Australia.

scholarly journals The COVID-19 outbreak in Sichuan, China: epidemiology and impact of interventions

2020 ◽  
Author(s):  
Quanhui Liu ◽  
Ana I Bento ◽  
Kexin Yang ◽  
Hang Zhang ◽  
Xiaohan Yang ◽  
...  
Keyword(s):  
Public Health ◽  
Control Strategies ◽  
Public Health Emergency ◽  
Control Measures ◽  
Patient Records ◽  
Epidemic Threshold ◽  
Reproduction Numbers ◽  
Imported Cases ◽  
The Impact ◽  
Local Transmission

In January 2020, a COVID19 outbreak was detected in Sichuan Province of China. The aim of this work is to characterize the epidemiology of the Sichuan outbreak and estimate the impact of the performed interventions. We analyzed patient records for all laboratory confirmed cases reported in the province for the period of January 21 to March 16, 2020. To estimate the basic and daily reproduction numbers, we used a Bayesian framework. In addition, we estimate the number of cases averted by the implemented control strategies. The outbreak resulted in 539 confirmed cases, lasted less than two months, and no further local transmission was detected after February 27. The median age of local cases was 8 years older than that of imported cases. Severity of symptoms increased with age. We estimated R0 at 2.4 (95% CI: 1.6-3.7). The epidemic was self sustained for about 3 weeks before going below the epidemic threshold 3 days after the declaration of a public health emergency by Sichuan authorities. Our findings indicate that, were the control measures be adopted four weeks later, the epidemic could have lasted 49 days longer (95%CI: 31-68 days), causing 9,216 (95%CI: 1,317-25,545) more cases and possibly overwhelming Sichuan healthcare system.

scholarly journals Transmissibility of coronavirus disease 2019 in Chinese cities with different dynamics of imported cases

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10350 ◽  
Author(s):  
Ka Chun Chong ◽  
Wei Cheng ◽  
Shi Zhao ◽  
Feng Ling ◽  
Kirran N. Mohammad ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Transmission Dynamics ◽  
Outbreak Response ◽  
Chinese Cities ◽  
Before And After ◽  
Imported Cases ◽  
Response Measures ◽  
The City ◽  
Local Transmission

Background Monitoring the reproduction number (Rt) of the disease could help determine whether there is sustained transmission in a population, but areas with similar epidemic trends could have different transmission dynamics given the risk from imported cases varied across regions. In this study, we examined the Rt of coronavirus disease 2019 (COVID-19) by taking different dynamics of imported cases into account and compared the transmissibility of COVID-19 at different intervention periods in Hangzhou and Shenzhen. Methods We obtained the daily aggregated counts of laboratory-confirmed imported and local cases of COVID-19 infections in Hangzhou and Shenzhen from January 1 to March 13, 2020. Daily Rt and piecewise Rt before and after Wuhan lockdown were estimated, accounting for imported cases. Results Since the epidemic of COVID-19 in Shenzhen was dominated by imported cases, Rt was around 0.1 to 0.7 before the Wuhan lockdown. After the lockdown of Wuhan and the initialization of measures in response to the outbreak, local transmission was well-controlled as indicated by a low estimated value of piecewise Rt, 0.15 (95% CI [0.09–0.21]). On the contrary, Rt obtained for Hangzhou ranged from 1.2 to 4.9 with a piecewise Rt of 2.55 (95% CI [2.13–2.97]) before the lockdown of Wuhan due to the surge in local cases. Because of the Wuhan lockdown and other outbreak response measures, Rt dropped below unity in mid-February. Conclusions Even though Shenzhen had more cases than Hangzhou, local transmission did not sustain probably due to limited transmission from imported cases owing to the reduction in local susceptibles as residents left the city during Chunyun. The lockdown measures and local outbreak responses helped reduce the local transmissibility.

scholarly journals Imported and autochthonous cases in the dynamics of dengue epidemics in Brazil

2009 ◽  
Vol 43 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Nicolas Degallier ◽  
Charly Favier ◽  
Jean-Philippe Boulanger ◽  
Christophe Menkes
Keyword(s):  
Basic Reproduction Number ◽  
Reproduction Number ◽  
Epidemiological Data ◽  
Epidemic Curve ◽  
Epidemic Dynamics ◽  
Reproduction Numbers ◽  
Imported Cases ◽  
And Control ◽  
Dengue Epidemic ◽  
The Basic Reproduction Number

OBJECTIVE: To estimate the basic reproduction number (R0) of dengue fever including both imported and autochthonous cases. METHODS: The study was conducted based on epidemiological data of the 2003 dengue epidemic in Brasília, Brazil. The basic reproduction number is estimated from the epidemic curve, fitting linearly the increase of initial cases. Aiming at simulating an epidemic with both autochthonous and imported cases, a "susceptible-infectious-resistant" compartmental model was designed, in which the imported cases were considered as an external forcing. The ratio between R0 of imported versus autochthonous cases was used as an estimator of real R0. RESULTS: The comparison of both reproduction numbers (only autochthonous versus all cases) showed that considering all cases as autochthonous yielded a R0 above one, although the real R0 was below one. The same results were seen when the method was applied on simulated epidemics with fixed R0. This method was also compared to some previous proposed methods by other authors and showed that the latter underestimated R0 values. CONCLUSIONS: It was shown that the inclusion of both imported and autochthonous cases is crucial for the modeling of the epidemic dynamics, and thus provides critical information for decision makers in charge of prevention and control of this disease.

scholarly journals The COVID-19 outbreak in Sichuan, China: Epidemiology and impact of interventions

2020 ◽  
Vol 16 (12) ◽  
pp. e1008467
Author(s):  
Quan-Hui Liu ◽  
Ana I. Bento ◽  
Kexin Yang ◽  
Hang Zhang ◽  
Xiaohan Yang ◽  
...  
Keyword(s):  
Public Health ◽  
Control Strategies ◽  
Public Health Emergency ◽  
Control Measures ◽  
Patient Records ◽  
Epidemic Threshold ◽  
Reproduction Numbers ◽  
Imported Cases ◽  
The Impact ◽  
Local Transmission

In January 2020, a COVID-19 outbreak was detected in Sichuan Province of China. Six weeks later, the outbreak was successfully contained. The aim of this work is to characterize the epidemiology of the Sichuan outbreak and estimate the impact of interventions in limiting SARS-CoV-2 transmission. We analyzed patient records for all laboratory-confirmed cases reported in the province for the period of January 21 to March 16, 2020. To estimate the basic and daily reproduction numbers, we used a Bayesian framework. In addition, we estimated the number of cases averted by the implemented control strategies. The outbreak resulted in 539 confirmed cases, lasted less than two months, and no further local transmission was detected after February 27. The median age of local cases was 8 years older than that of imported cases. We estimated R0 at 2.4 (95% CI: 1.6–3.7). The epidemic was self-sustained for about 3 weeks before going below the epidemic threshold 3 days after the declaration of a public health emergency by Sichuan authorities. Our findings indicate that, were the control measures be adopted four weeks later, the epidemic could have lasted 49 days longer (95% CI: 31–68 days), causing 9,216 more cases (95% CI: 1,317–25,545).

Examining Organizational, Cultural, and Individual-Level Factors Related to Workplace Safety and Health Awareness and Risks: A Systematic Review and Metric Analysis (Preprint)

2018 ◽  
Author(s):  
Edmund W. J. Lee ◽  
Han Zheng ◽  
Htet Htet Aung ◽  
Megha Rani Aroor ◽  
Chen Li ◽  
...  
Keyword(s):  
Systematic Review ◽  
Citation Count ◽  
Workplace Safety ◽  
Key Factors ◽  
Health Awareness ◽  
Individual Level ◽  
Metric Analysis ◽  
Safety And Health ◽  
The Impact ◽  
The Relationship

BACKGROUND Promoting safety and health awareness and mitigating risks are of paramount importance to companies in high-risk industries. Yet, there are very few studies that have synthesized findings from existing online workplace safety and health literature to identify what are the key factors that are related to (a) safety awareness, (b) safety risks, (c) health awareness, and (d) health risks. OBJECTIVE As one of the first systematic reviews in the area of workplace health and safety, this study aims to identify the factors related to safety and health awareness as well as risks, and systematically map these factors within three levels: organizational, cultural, and individual level. Also, this review aims to assess the impact of these workplace safety and health publications in both academic (e.g., academic databases, Mendeley, and PlumX) and non-academic settings (e.g., social media platform). METHODS The systematic review was conducted in line with procedures recommended by Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). First, Proquest, ScienceDirect and Scopus were identified as suitable databases for the systematic review. Second, after inputting search queries related to safety and health awareness and risks, the articles were evaluated based on a set of inclusion and exclusion criteria. Third, the factors identified in the included articles were coded systematically. Fourth, the research team assessed the impact of the articles through a combination of traditional and new metric analysis methods: citation count, Altmetric Attention Score, Mendeley readers count, usage count, and capture count. RESULTS Out of a total of 4,831 articles retrieved from the three databases, 51 articles were included in the final sample and were systematically coded. The results revealed six categories of organizational (management commitment, management support, organizational safety communication, safety management systems, physical work environment, and organizational environment), two cultural (interpersonal support and organizational culture), and four individual (perception, motivation, attitude and behavior) level factors that relate to safety and health awareness and risk. In terms of impact, the relationship between citation count and the various metrics measuring academic activity (e.g., Mendeley readers, usage count, and capture count) were mostly significant while the relationship between citation count and Altmetric Attention Score was non-significant. CONCLUSIONS This study provides a macro view of the current state of workplace safety and health research and gives scholars an indication on some of the key factors of safety and health awareness and risks. Researchers should also be cognizant that while their work may receive attention from the scholarly community, it is important to tailor their communication messages for the respective industries they are studying to maximize the receptivity and impact of their findings. CLINICALTRIAL N.A.

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