scholarly journals Household Representative Sample Strategy for COVID-19 Large-Scale Population Screening

2020 ◽  
Author(s):  
John Takyi-Williams
Keyword(s):  
Continuous Monitoring ◽  
Large Scale ◽  
Group Testing ◽  
Detection Sensitivity ◽  
Disease Group ◽  
Testing Method ◽  
Scale Population ◽  
Virus Exposure ◽  
Pooled Samples ◽  
Sample Dilution

In the advent of COVID-19 pandemic, testing is highly essential to be able to isolate, treat infected persons, and finally curb transmission of this infectious respiratory disease. Group testing has been used previously for various infectious diseases and recently reported for large-scale population testing of COVID-19. However, possible sample dilution as a result of large pool sizes has been reported, limiting testing methods’ detection sensitivity. Moreover, the need to sample all individuals prior to pooling overburden the limited resources such as test kits. An alternative proposed strategy where test is performed on pooled samples from individuals representing different households is presented here. This strategy intends to improve group testing method through the reduction in the number of samples collected and pooled during large-scale population testing. Moreover, it introduces database system which enables continuous monitoring of the population’s virus exposure for better decision making.

scholarly journals Swab pooling for large-scale RT-qPCR screening of SARS-CoV-2

2020 ◽  
Author(s):  
Ana Paula Christoff ◽  
Giuliano Netto Flores Cruz ◽  
Aline Fernanda Rodrigues Sereia ◽  
Dellyana Rodrigues Boberg ◽  
Daniela Carolina de Bastiani ◽  
...  
Keyword(s):  
Large Scale ◽  
Sample Collection ◽  
Laboratory Capacity ◽  
Positive Individual ◽  
Sample Pooling ◽  
Pooling Strategies ◽  
Low Prevalence ◽  
Pooled Samples ◽  
Sample Dilution ◽  
Large Scale Screening

Pool testing has been proposed as an alternative for large-scale SARS-CoV-2 screening. However, dilution factors proportional to the number of pooled samples have been a source of major concern regarding its diagnostic performance. Further, sample pooling can lead to increased laboratory workload and operational complexity. Therefore, pooling strategies that minimize sample dilution, loss of sensitivity, and laboratory overload are needed to allow reliable and large-scale screenings of SARS-CoV-2. Here, we describe a pooling procedure in which nasopharyngeal swabs are pooled together at the time of sample collection (swab pooling), decreasing laboratory manipulation and minimizing dilution of the viral RNA present in the samples. Paired analysis of pooled and individual samples from 613 patients revealed 94 positive individual tests. Having individual testing as a reference, no false-positives or false-negatives were observed for swab pooling. A Bayesian model estimated a sensitivity of 99% (Cr.I. 96.9% to 100%) and a specificity of 99.8% (Cr.I. 99.4% to 100%) for the swab pooling procedure. Data from additional 18,922 patients screened with swab pooling were included for further quantitative analysis. Mean Cq differences between individual and corresponding pool samples ranged from 0.1 Cq (Cr.I. -0.98 to 1.17) to 2.09 Cq (Cr.I. 1.24 to 2.94). Overall, 19,535 asymptomatic and presymptomatic patients were screened using 4,400 RT-qPCR assays, resulting in 246 positive patients (positivity rate 1.26%). This corresponds to an increase of 4.4 times in laboratory capacity and a reduction of 77% in required tests. Finally, these data demonstrate that swab pooling can significantly minimize sample dilution and sensitivity issues commonly seen in its traditional counterpart. Therefore, swab pooling represents a major alternative for reliable and large-scale screening of SARS-CoV-2 in low prevalence populations.

scholarly journals Group testing as a strategy for COVID-19 epidemiological monitoring and community surveillance

2021 ◽  
Vol 17 (3) ◽  
pp. e1008726
Author(s):  
Vincent Brault ◽  
Bastien Mallein ◽  
Jean-François Rupprecht
Keyword(s):  
Viral Load ◽  
Statistical Model ◽  
Large Scale ◽  
Infected Individual ◽  
Group Testing ◽  
Epidemic Outbreak ◽  
False Negatives ◽  
Testing Method ◽  
Epidemiological Monitoring ◽  
Sample Pooling

We propose an analysis and applications of sample pooling to the epidemiologic monitoring of COVID-19. We first introduce a model of the RT-qPCR process used to test for the presence of virus in a sample and construct a statistical model for the viral load in a typical infected individual inspired by large-scale clinical datasets. We present an application of group testing for the prevention of epidemic outbreak in closed connected communities. We then propose a method for the measure of the prevalence in a population taking into account the increased number of false negatives associated with the group testing method.

scholarly journals Multi-Stage Group Testing Improves Efficiency of Large-Scale COVID-19 Screening

2020 ◽  
Author(s):  
JN Eberhardt ◽  
NP Breuckmann ◽  
CS Eberhardt
Keyword(s):  
Computer Simulations ◽  
Large Scale ◽  
Group Testing ◽  
Prevalence Rates ◽  
Single Test ◽  
Multi Stage ◽  
Scale Population ◽  
Major Reduction ◽  
Pool Sizes ◽  
Multiple Stages

AbstractBackgroundSARS-CoV-2 test kits are in critical shortage in many countries. This limits large-scale population testing and hinders the effort to identify and isolate infected individuals.ObjectivesHerein, we developed and evaluated multi-stage group testing schemes that test samples in groups of various pool sizes in multiple stages. Through this approach, groups of negative samples can be eliminated with a single test, avoiding the need for individual testing and achieving considerable savings of resources.Study designWe designed and parameterized various multi-stage testing schemes and compared their efficiency at different prevalence rates using computer simulations.ResultsWe found that three-stage testing schemes with pool sizes of maximum 16 samples can test up to three and seven times as many individuals with the same number of test kits for prevalence rates of around 5% and 1%, respectively. We propose an adaptive approach, where the optimal testing scheme is selected based on the expected prevalence rate.ConclusionThese group testing schemes could lead to a major reduction in the number of testing kits required and help improve large-scale population testing in general and in the context of the current COVID-19 pandemic.

scholarly journals Publisher Correction: A link between appendectomy and gastrointestinal cancers: a large-scale population-based cohort study in Korea

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Youn Young Park ◽  
Kil‑yong Lee ◽  
Seong Taek Oh ◽  
Sang Hyun Park ◽  
Kyung Do Han ◽  
...  
Keyword(s):  
Cohort Study ◽  
Large Scale ◽  
Population Based ◽  
Gastrointestinal Cancers ◽  
Scale Population

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

scholarly journals Using Bus Ticketing Big Data to Investigate the Behaviors of the Population Flow of Chinese Suburban Residents in the Post-COVID-19 Phase

2021 ◽  
Vol 18 (11) ◽  
pp. 6066
Author(s):  
Yanbing Bai ◽  
Lu Sun ◽  
Haoyu Liu ◽  
Chao Xie
Keyword(s):  
Travel Behavior ◽  
Large Scale ◽  
Behavior Patterns ◽  
Population Movements ◽  
Economic Level ◽  
Passenger Travel ◽  
Scale Population ◽  
Travel Behaviors ◽  
Railway Passenger ◽  
And Control

Large-scale population movements can turn local diseases into widespread epidemics. Grasping the characteristic of the population flow in the context of the COVID-19 is of great significance for providing information to epidemiology and formulating scientific and reasonable prevention and control policies. Especially in the post-COVID-19 phase, it is essential to maintain the achievement of the fight against the epidemic. Previous research focuses on flight and railway passenger travel behavior and patterns, but China also has numerous suburban residents with a not-high economic level; investigating their travel behaviors is significant for national stability. However, estimating the impacts of the COVID-19 for suburban residents’ travel behaviors remains challenging because of lacking apposite data. Here we submit bus ticketing data including approximately 26,000,000 records from April 2020–August 2020 for 2705 stations. Our results indicate that Suburban residents in Chinese Southern regions are more likely to travel by bus, and travel frequency is higher. Associated with the economic level, we find that residents in the economically developed region more likely to travel or carry out various social activities. Considering from the perspective of the traveling crowd, we find that men and young people are easier to travel by bus; however, they are exactly the main workforce. The indication of our findings is that suburban residents’ travel behavior is affected profoundly by economy and consistent with the inherent behavior patterns before the COVID-19 outbreak. We use typical regions as verification and it is indeed the case.

scholarly journals High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

2021 ◽  
Vol 11 (15) ◽  
pp. 6992
Author(s):  
Tie Zhang ◽  
Yuxin Xing ◽  
Gaoxuan Wang ◽  
Sailing He
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Continuous Monitoring ◽  
Near Infrared ◽  
Resonant Cavity ◽  
High Sensitivity ◽  
Industrial Applications ◽  
Detection Sensitivity ◽  
Infrared Range ◽  
Wavelength Modulation ◽  
Linear Coefficient

An optical system for gaseous chloroform (CHCl3) detection based on wavelength modulation photoacoustic spectroscopy (WMPAS) is proposed for the first time by using a distributed feedback (DFB) laser with a center wavelength of 1683 nm where chloroform has strong and complex absorption peaks. The WMPAS sensor developed possesses the advantages of having a simple structure, high-sensitivity, and direct measurement. A resonant cavity made of stainless steel with a resonant frequency of 6390 Hz was utilized, and eight microphones were located at the middle of the resonator at uniform intervals to collect the sound signal. All of the devices were integrated into an instrument box for practical applications. The performance of the WMPAS sensor was experimentally demonstrated with the measurement of different concentrations of chloroform from 63 to 625 ppm. A linear coefficient R2 of 0.999 and a detection sensitivity of 0.28 ppm with a time period of 20 s were achieved at room temperature (around 20 °C) and atmosphere pressure. Long-time continuous monitoring for a fixed concentration of chloroform gas was carried out to demonstrate the excellent stability of the system. The performance of the system shows great practical value for the detection of chloroform gas in industrial applications.

scholarly journals Maternal adherence to micronutrient supplementation before and during pregnancy in Northwest China: a large-scale population-based cross-sectional survey

BMJ Open ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. e028843 ◽  
Author(s):  
Danmeng Liu ◽  
Yue Cheng ◽  
Shaonong Dang ◽  
Duolao Wang ◽  
Yaling Zhao ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Large Scale ◽  
Northwest China ◽  
Population Based ◽  
Shaanxi Province ◽  
Micronutrient Supplementation ◽  
Cross Sectional Survey ◽  
Start Time ◽  
Cross Sectional ◽  
Scale Population

ObjectivesTo report the situation of maternal micronutrient supplementation before and during pregnancy in Northwest China and to examine the rates of and factors related to the adherence to micronutrient supplementation among pregnant women in this region, where dietary micronutrient intake is commonly insufficient.DesignA large-scale population-based cross-sectional survey.SettingTwenty counties and ten districts of Shaanxi Province.ParticipantsA sample of 30 027 women were selected using a stratified multistage random sampling method. A total of 28 678 women were chosen for the final analysis after excluding those who did not provide clear information about nutritional supplementation before and during pregnancy.Main outcome measuresMaternal adherence to micronutrient supplementation (high and low) were the outcomes. They were determined by the start time and duration of use according to Chinese guidelines (for folic acid (FA) supplements) and WHO recommendations (for iron, calcium and multiple-micronutrient (MMN) supplements).ResultsIn total, 83.9% of women took at least one kind of micronutrient supplement before or during pregnancy. FA (67.6%) and calcium (57.5%) were the primarily used micronutrient supplements; few participants used MMN (14.0%) or iron (5.4%). Adherence to supplementation of all micronutrients was low (7.4% for FA, 0.6% for iron, 11.7% for calcium and 2.7% for MMN). Higher educational levels, higher income levels, urban residence and better antenatal care (including pregnancy consultation and a higher frequency of antenatal visits) were associated with high adherence to micronutrient supplementation.ConclusionMaternal micronutrient supplementation before and during pregnancy in Northwest China was way below standards recommended by the Chinese guidelines or WHO. Targeted health education and future nutritional guidelines are suggested to improve this situation, especially in pregnant women with disadvantaged sociodemographic conditions.

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