scholarly journals Transmission dynamics and the effects of non-pharmaceutical interventions in the COVID-19 outbreak resurged in Beijing, China: a descriptive and modelling study

BMJ Open ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. e047227
Author(s):  
Xiaoming Cui ◽  
Lin Zhao ◽  
Yuhao Zhou ◽  
Xin Lin ◽  
Runze Ye ◽  
...  
Keyword(s):  
Close Contact ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Population Mobility ◽  
Wholesale Market ◽  
The People ◽  
Spatiotemporal Analyses ◽  
Epidemiological Characteristics ◽  
Pharmaceutical Interventions ◽  
Modelling Study

ObjectiveTo evaluate epidemiological characteristics and transmission dynamics of COVID-19 outbreak resurged in Beijing and to assess the effects of three non-pharmaceutical interventions.DesignDescriptive and modelling study based on surveillance data of COVID-19 in Beijing.SettingOutbreak in Beijing.ParticipantsThe database included 335 confirmed cases of COVID-19.MethodsTo conduct spatiotemporal analyses of the outbreak, we collected individual records on laboratory-confirmed cases of COVID-19 from 11 June 2020 to 5 July 2020 in Beijing, and visitor flow and products transportation data of Xinfadi Wholesale Market. We also built a modified susceptible-exposed-infected-removed model to investigate the effect of interventions deployed in Beijing.ResultsWe found that the staff working in the market (52.2%) and the people around 10 km to this epicentre (72.5%) were most affected, and the population mobility entering-exiting Xinfadi Wholesale Market significantly contributed to the spread of COVID-19 (p=0.021), but goods flow of the market had little impact on the virus spread (p=0.184). The prompt identification of Xinfadi Wholesale Market as the infection source could have avoided a total of 25 708 (95% CI 13 657 to 40 625) cases if unnoticed transmission lasted for a month. Based on the model, we found that active screening on targeted population by nucleic acid testing alone had the most significant effect.ConclusionsThe non-pharmaceutical interventions deployed in Beijing, including localised lockdown, close-contact tracing and community-based testing, were proved to be effective enough to contain the outbreak. Beijing has achieved an optimal balance between epidemic containment and economic protection.

scholarly journals Evaluation of the Design and Implementation of a Peer-To-Peer COVID-19 Contact Tracing Mobile App (COCOA) in Japan

10.2196/22098 ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. e22098
Author(s):  
Ichiro Nakamoto ◽  
Ming Jiang ◽  
Jilin Zhang ◽  
Weiqing Zhuang ◽  
Yan Guo ◽  
...  
Keyword(s):  
Close Contact ◽  
Health Care Systems ◽  
Participation Rate ◽  
Peer To Peer ◽  
Mobile App ◽  
Contact Tracing ◽  
Population Mobility ◽  
Excessive Pressure ◽  
Public Authorities ◽  
Care Systems

We evaluate a Bluetooth-based mobile contact-confirming app, COVID-19 Contact-Confirming Application (COCOA), which is being used in Japan to contain the spread of COVID-19, the disease caused by the novel virus termed SARS-COV-2. The app prioritizes the protection of users’ privacy from a variety of parties (eg, other users, potential attackers, and public authorities), enhances the capacity to balance the current load of excessive pressure on health care systems (eg, local triage of exposure risk and reduction of in-person hospital visits), increases the speed of responses to the pandemic (eg, automated recording of close contact based on proximity), and reduces operation errors and population mobility. The peer-to-peer framework of COCOA is intended to provide the public with dynamic and credible updates on the COVID-19 pandemic without sacrificing the privacy of their information. However, cautions must be exercised to address critical concerns, such as the rate of participation and delays in data sharing. The results of a simulation imply that the participation rate in Japan needs to be close 90% to effectively control the spread of COVID-19.

scholarly journals Mobile Clustering Scheme for Pedestrian Contact Tracing: The COVID-19 Case Study

Entropy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 326
Author(s):  
Mario E. Rivero-Angeles ◽  
Víctor Barrera-Figueroa ◽  
José E. Malfavón-Talavera ◽  
Yunia V. García-Tejeda ◽  
Izlian Y. Orea-Flores ◽  
...  
Keyword(s):  
Smart Cities ◽  
Close Contact ◽  
Packet Transmission ◽  
Collision Probability ◽  
Contact Tracing ◽  
Gps Tracking ◽  
Virus Propagation ◽  
Detection Range ◽  
Area Of Interest ◽  
The People

In the context of smart cities, there is a general benefit from monitoring close encounters among pedestrians. For instance, for the access control to office buildings, subway, commercial malls, etc., where a high amount of users may be present simultaneously, and keeping a strict record on each individual may be challenging. GPS tracking may not be available in many indoor cases; video surveillance may require expensive deployment (mainly due to the high-quality cameras and face recognition algorithms) and can be restrictive in case of low budget applications; RFID systems can be cumbersome and limited in the detection range. This information can later be used in many different scenarios. For instance, in case of earthquakes, fires, and accidents in general, the administration of the buildings can have a clear record of the people inside for victim searching activities. However, in the pandemic derived from the COVID-19 outbreak, a tracking that allows detecting of pedestrians in close range (a few meters) can be particularly useful to control the virus propagation. Hence, we propose a mobile clustering scheme where only a selected number of pedestrians (Cluster Heads) collect the information of the people around them (Cluster Members) in their trajectory inside the area of interest. Hence, a small number of transmissions are made to a control post, effectively limiting the collision probability and increasing the successful registration of people in close contact. Our proposal shows an increased success packet transmission probability and a reduced collision and idle slot probability, effectively improving the performance of the system compared to the case of direct transmissions from each node.

scholarly journals Signatures of the Venezuelan Humanitarian Crisis in the First Wave of COVID-19: Fuel Shortages and Border Migration

Vaccines ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 719
Author(s):  
Margarita Lampo ◽  
Juan V. Hernández-Villena ◽  
Jaime Cascante ◽  
María F. Vincenti-González ◽  
David A. Forero-Peña ◽  
...  
Keyword(s):  
Latin America ◽  
Spatial Epidemiology ◽  
Transmission Dynamics ◽  
Population Movement ◽  
Population Mobility ◽  
Metapopulation Model ◽  
Humanitarian Crisis ◽  
Migration Patterns ◽  
Border States ◽  
Pharmaceutical Interventions

Testing and isolation have been crucial for controlling the COVID-19 pandemic. Venezuela has one of the weakest testing infrastructures in Latin America and the low number of reported cases in the country has been attributed to substantial underreporting. However, the Venezuelan epidemic seems to have lagged behind other countries in the region, with most cases occurring within the capital region and four border states. Here, we describe the spatial epidemiology of COVID-19 in Venezuela and its relation to the population mobility, migration patterns, non-pharmaceutical interventions and fuel availability that impact population movement. Using a metapopulation model of SARS-CoV-2 transmission dynamics, we explore how movement patterns could have driven the observed distribution of cases. Low within-country connectivity most likely delayed the onset of the epidemic in most states, except for those bordering Colombia and Brazil, where high immigration seeded outbreaks. NPIs slowed early epidemic growth and subsequent fuel shortages appeared to be responsible for limiting the spread of COVID-19 across the country.

scholarly journals Epidemiological investigation of a COVID-19 family cluster outbreak transmitted by a 3-month-old infant

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Guo-tian Lin ◽  
Yue-hua Zhang ◽  
Mei-fang Xiao ◽  
Yong Wei ◽  
Jin-ni Chen ◽  
...  
Keyword(s):  
Close Contact ◽  
Contact Tracing ◽  
Epidemiological Methods ◽  
Oral Transmission ◽  
Family Cluster ◽  
Serum Igg ◽  
First Case ◽  
Hospital Patients ◽  
Fecal Tests ◽  
Epidemiological Characteristics

Abstract Objective To investigate the clinical characteristics, epidemiological characteristics, and transmissibility of coronavirus disease 2019 (COVID-19) in a family cluster outbreak transmitted by a 3-month-old confirmed positive infant. Methods Field-based epidemiological methods were used to investigate cases and their close contacts. Real-time fluorescent reverse transcription polymerase chain reaction (RT-PCR) was used to detect Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) for all collected specimens. Serum SARS-CoV-2 IgM and IgG antibodies were detected by Chemiluminescence and Gold immnnochromatography (GICA). Results The outbreak was a family cluster with an attack rate of 80% (4/5). The first case in this family was a 3-month-old infant. The transmission chain was confirmed from infant to adults (her father, mother and grandmother). Fecal tests for SARS-CoV-2 RNA remained positive for 37 days after the infant was discharged. The infant’s grandmother was confirmed to be positive 2 days after the infant was discharged from hospital. Patients A (3-month-old female), B (patient A’s father), C (patient A’s grandmother), and D (patient A’s mother) had positive serum IgG and negative IgM, but patients A’s grandfather serum IgG and IgM were negative. Conclusion SARS-CoV-2 has strong transmissibility within family settings and presence of viral RNA in stool raises concern for possible fecal–oral transmission. Hospital follow-up and close contact tracing are necessary for those diagnosed with COVID-19.

scholarly journals Transmission Risk of SARS-CoV-2 Among Close Contacts- Results of Case- Contact Tracing

2020 ◽  
Author(s):  
Haimei Jia ◽  
Minhong CHen ◽  
Hanwei Wang ◽  
Chenping Guan ◽  
Yangwei Chen ◽  
...  
Keyword(s):  
Virus Disease ◽  
Close Contact ◽  
Secondary Infection ◽  
Transmission Risk ◽  
Contact Tracing ◽  
Anal Swab ◽  
Novel Coronavirus ◽  
Asymptomatic Case ◽  
Epidemiological Characteristics ◽  
Close Contacts

Abstract Background: The ongoing outbreak of corona virus Disease-19 (COVID-19) is rapid escalation and global spread.The epidemiological characteristics and particularly its ability to spread in the human population of COVID-19 were uncertainty. We analyzed infection of 2019 novel coronavirus pneumonia (COVID-19) and close contacts in Fuzhou, Fujian Province, and to understand the risk of infection and morbidity in different exposure mode. Methods: We investigated cases and their close contacts by face-to –face or telephone interview and conducted laboratory test on nasopharyngeal or oropharyngeal swabs or anal swab for evidence of COVID-19 infection. Information on cases including the epidemiology, expose and laboratory were collected. Results: There were 72 patients of COVID-19 and 1 asymptomatic case were confirmed in Fuzhou. A total of 1159 close contacts were traced, the secondary infection rate (SIR) was 2.07% (24/1159), the median of interval was 12 days (rang 2-21 days). In the relationship between close contact and cases, the SIR of old people under care were the highest (28.57% ) than family members (5.52%), medical staff (3.23%), relatives (2.41%) and colleagues / classmates (1.67%), respectively( 2＝534.38， P＜0.00 ). Among the contact ways, the SIR of Nursing (nursing home) were the highest (28.57% ) than medical care (3.23%), family gathering (2.82%), same building (1.77%) and short talk or handle affairs (1.55%),respectively. The median of incubation period was 5days (rang1-12days). Conclusions: The COVID-19 has highly contagious. Timely and strict quarantine should be conducted for close contacts to reduce the possibility of community communication.

scholarly journals Universal community nucleic acid testing for COVID-19 in Hong Kong reveals insights into transmission dynamics

2021 ◽  
Author(s):  
Bingyi Yang ◽  
Tim K. Tsang ◽  
Huizhi Gao ◽  
Eric H. Y. Lau ◽  
Yun Lin ◽  
...  
Keyword(s):  
Public Health ◽  
Hong Kong ◽  
Clinical Diagnosis ◽  
Public Health Surveillance ◽  
Credible Interval ◽  
Health Surveillance ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Third Wave ◽  
Epidemiological Characteristics

Abstract Background: Testing of an entire community has been used as an approach to control COVID-19. In Hong Kong, a universal community testing programme (UCTP) was implemented at the fadeout phase of a community epidemic in July to September 2020, to determine the prevalence of unrecognised cases and limit any remaining transmission chains. We described the utility of the UCTP in finding unrecognised cases, and analysed data from the UCTP and other sources to characterise transmission dynamics.Methods: We described the characteristics of people participating in the UCTP, and compared the clinical and epidemiological characteristics of COVID-19 cases detected by the UCTP versus those detected by clinical diagnosis and public health surveillance. We developed a Bayesian model to estimate the age-specific incidence of infection and the proportion of cases detected by clinical diagnosis and public health surveillance.Findings: 1.77 million people, 24% of the Hong Kong population, participated in the UCTP from 1 to 14 September 2020. The UCTP identified 32 new infections (1.8 per 100,000 samples tested), consisting of 29% of all local cases reported during the two-week UCTP period. Compared with the existing clinical diagnosis and public health surveillance, the UCTP detected a higher proportion of sporadic cases (62% versus 27%, p <0.01) and identified 6 (out of 18) additional transmission chains during that period. We estimated that 27% (95% credible interval: 22%, 34%) of all infections were detected by the existing clinical diagnosis and public health surveillance in the third wave.Interpretation: We reported empirical evidence of the utility of population-wide COVID-19 testing in detecting unrecognised infections and transmission chains. Around three quarters of infections have not been identified through existing surveillance approaches including contact tracing.

scholarly journals Evaluation of the Design and Implementation of a Peer-To-Peer COVID-19 Contact Tracing Mobile App (COCOA) in Japan (Preprint)

2020 ◽  
Author(s):  
Ichiro Nakamoto ◽  
Ming Jiang ◽  
Jilin Zhang ◽  
Weiqing Zhuang ◽  
Yan Guo ◽  
...  
Keyword(s):  
Close Contact ◽  
Health Care Systems ◽  
Participation Rate ◽  
Peer To Peer ◽  
Mobile App ◽  
Contact Tracing ◽  
Population Mobility ◽  
Excessive Pressure ◽  
Public Authorities ◽  
Care Systems

UNSTRUCTURED We evaluate a Bluetooth-based mobile contact-confirming app, COVID-19 Contact-Confirming Application (COCOA), which is being used in Japan to contain the spread of COVID-19, the disease caused by the novel virus termed SARS-COV-2. The app prioritizes the protection of users’ privacy from a variety of parties (eg, other users, potential attackers, and public authorities), enhances the capacity to balance the current load of excessive pressure on health care systems (eg, local triage of exposure risk and reduction of in-person hospital visits), increases the speed of responses to the pandemic (eg, automated recording of close contact based on proximity), and reduces operation errors and population mobility. The peer-to-peer framework of COCOA is intended to provide the public with dynamic and credible updates on the COVID-19 pandemic without sacrificing the privacy of their information. However, cautions must be exercised to address critical concerns, such as the rate of participation and delays in data sharing. The results of a simulation imply that the participation rate in Japan needs to be close 90% to effectively control the spread of COVID-19.

scholarly journals A Comparative Retrospective Study of COVID-19 Responses in Four Countries

2021 ◽  
Author(s):  
Xiaohan Wang ◽  
Leiyu Shi ◽  
Yuyao Zhang ◽  
Haiqian Chen ◽  
Jun Jiao ◽  
...  
Keyword(s):  
Retrospective Study ◽  
South Korea ◽  
Large Scale ◽  
Close Contact ◽  
Health Care Systems ◽  
Government Policies ◽  
Contact Tracing ◽  
Effective Measure ◽  
The Government ◽  
Pharmaceutical Interventions

Abstract Objective This study compared the government policies and non-pharmaceutical interventions adopted by South Korea, Japan, India, and China in response to COVID-19 during 2020-2021. We hope that our study would propose policies for future COVID-19 waves and provide lessons for future responses to similar infectious diseases.Methods We made a retrospective study by analyzing the government policies and non-pharmaceutical interventions in these four countries. Results From January 2020 to May 18, 2021, South Korea and Japan experienced three waves of COVID-19 epidemic, but the number of daily new confirmed cases per million people was relatively small in both countries, and South Korea had fewer daily new confirmed cases per million than Japan. Following the COVID-19 outbreak in Wuhan in late 2019, China successfully contained the first wave of the outbreak and is not currently experiencing a large-scale resurgence of the epidemic. India is experiencing a grim second wave of the epidemic, with far more daily new confirmed cases per million people than South Korea and Japan. Throughout 2020, the number of COVID-19 deaths per million population remains low in South Korea, Japan, and China, while India has seen an upward trend in deaths per million population since July. As of May 18, 2021, the number of total tests per thousand people in South Korea, India, and Japan was 230.65, 181.23, and 99.59, respectively. South Korea and India both have more than twice as total tests per thousand people as Japan.Conclusion Successful practices in China and South Korea show that--case identification and management, coupled with close contact tracing and isolation, is a powerful strategy. The lessons of Japan and India show that social distancing is an effective measure, but only if it is rigor and persistent. Finally, in both developed and developing countries, the development of health care systems and coordinated government leadership play a key role in overcoming epidemics.

Embedding Isolation, Contact Tracing, and Quarantine in Transmission Dynamics of the Coronavirus Epidemic—A Case Study of COVID-19 in Wuhan

2021 ◽  
Author(s):  
Miao Yu ◽  
Zhongsheng Hua
Keyword(s):  
Close Contact ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Social Distancing ◽  
Infected People ◽  
Epidemic Curve ◽  
Specific Effects ◽  
Lag Effect ◽  
Novel Coronavirus

Coronaviruses have caused multiple global pandemics. As an emerging epidemic, the coronavirus disease relies on nonpharmacological interventions to control its spread. However, the specific effects of these interventions are unknown. To evaluate their effects, we extend the susceptible–latent–infectious–recovered model to include suspected cases, confirmed cases, and their contacts and to embed isolation, close contact tracing, and quarantine into transmission dynamics. The model simplifies the population into two parts: the undiscovered part (where the virus spreads freely—the extent of freedom is determined by the strength of social distancing policy) and the discovered part (where the cases are incompletely isolated or quarantined). Through the isolation of the index case (suspected or confirmed case) and the subsequent tracing and quarantine of its close contacts, the infections flow from the undiscovered part to the discovered part. In our case study, multisource data of the novel coronavirus SARS-CoV-2 (COVID-19) in Wuhan were collected to validate the model, the parameters were calibrated based on the prediction of the actual number of infections, and then the time-varying effective reproduction number was obtained to measure the transmissibility of COVID-19 in Wuhan, revealing the timeliness and lag effect of the nonpharmacological interventions adopted there. Finally, we simulated the situation in the absence of a strict social distancing policy. Results show that the current efforts of isolation, close contact tracing, and quarantine can take the epidemic curve to the turning point, but the epidemic could be far from over; there were still 4,035 infected people, and 1,584 latent people in the undiscovered part on March 11, 2020, when the epidemic was actually over with a strict social distancing policy.

An Epidemiological Analysis of COVID-19 Confirmed Cases, Reported at National Institute of Health, Pakistan (Preprint)

2020 ◽  
Author(s):  
Ambreen Chaudhry
Keyword(s):  
Age Groups ◽  
Target Population ◽  
Control Measures ◽  
Contact Tracing ◽  
Bivariate Analysis ◽  
Travel History ◽  
Disease Epidemiology ◽  
Hygiene Practices ◽  
Multi Center Study ◽  
Epidemiological Characteristics

BACKGROUND Coronavirus disease (Covid-19) is a zoonotic disease of novel origin that posed a continuous threat to health worldwide after taking the shape of the pandemic. An understanding of disease epidemiology is supportive in timely preventive and control measures as well as contact tracing and curbing surveillance activities. OBJECTIVE The objective of our study was to determine the epidemiological characteristics of COVID-19 confirmed cases reported at the National Institute of Health Pakistan and elements of its spread in Pakistan. METHODS A retrospective record review was conducted at the National Institute of Health (NIH) Islamabad, Pakistan from January 25 to April 4, 2020. Univariate and bivariate analysis was done with 95% CI and p<0.05. RESULTS A total of 14,422 samples of suspected COVID-19 cases were received with a positivity rate of 9% (n=1348). Among all 70% (n=939) were male. The median age was 41years of age (range: 01-99Years). Among all, 19% were from 30-39 years old followed by 50-59 years old (17%). Children remained the least affected by 3% (n=35). Of the total reported cases, 55% (n=735) have reported the travel history within the last 14 days. Among these travelers’ international travelers were 23% (n=166) and domestic travelers were 77% (n=569). Travel history including both international and domestic remained significantly associated with the different age groups and Young adults remained more vulnerable to COVID-19 (P=0.03). Fever, SOB, and Cough remained the most significantly associated (P<0.05) in all age groups. CONCLUSIONS A higher incidence of COVID-19 among elderly men suggests robust quarantine measures for this target population. An escalating incidence of local transmission needs strict social distancing and hygiene practices to help flatten the curve. An extensive multi-center study is also recommended for a full understanding of disease dynamics.

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