scholarly journals High variability in transmission of SARS-CoV-2 within households and implications for control

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259097
Author(s):  
Damon J. A. Toth ◽  
Alexander B. Beams ◽  
Lindsay T. Keegan ◽  
Yue Zhang ◽  
Tom Greene ◽  
...  
Keyword(s):  
Test Data ◽  
Attack Rate ◽  
Serological Test ◽  
Close Contact ◽  
Antibody Test ◽  
High Variability ◽  
Test Accuracy ◽  
Household Transmission ◽  
Wide Range ◽  
Test Specificity

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a high risk of transmission in close-contact indoor settings, which may include households. Prior studies have found a wide range of household secondary attack rates and may contain biases due to simplifying assumptions about transmission variability and test accuracy. Methods We compiled serological SARS-CoV-2 antibody test data and prior SARS-CoV-2 test reporting from members of 9,224 Utah households. We paired these data with a probabilistic model of household importation and transmission. We calculated a maximum likelihood estimate of the importation probability, mean and variability of household transmission probability, and sensitivity and specificity of test data. Given our household transmission estimates, we estimated the threshold of non-household transmission required for epidemic growth in the population. Results We estimated that individuals in our study households had a 0.41% (95% CI 0.32%– 0.51%) chance of acquiring SARS-CoV-2 infection outside their household. Our household secondary attack rate estimate was 36% (27%– 48%), substantially higher than the crude estimate of 16% unadjusted for imperfect serological test specificity and other factors. We found evidence for high variability in individual transmissibility, with higher probability of no transmissions or many transmissions compared to standard models. With household transmission at our estimates, the average number of non-household transmissions per case must be kept below 0.41 (0.33–0.52) to avoid continued growth of the pandemic in Utah. Conclusions Our findings suggest that crude estimates of household secondary attack rate based on serology data without accounting for false positive tests may underestimate the true average transmissibility, even when test specificity is high. Our finding of potential high variability (overdispersion) in transmissibility of infected individuals is consistent with characterizing SARS-CoV-2 transmission being largely driven by superspreading from a minority of infected individuals. Mitigation efforts targeting large households and other locations where many people congregate indoors might curb continued spread of the virus.

scholarly journals High variability in transmission of SARS-CoV-2 within households and implications for control

2021 ◽  
Author(s):  
Damon J.A. Toth ◽  
Alexander B. Beams ◽  
Lindsay T. Keegan ◽  
Yue Zhang ◽  
Tom Greene ◽  
...  
Keyword(s):  
Test Data ◽  
Attack Rate ◽  
Serological Test ◽  
Close Contact ◽  
Antibody Test ◽  
High Variability ◽  
Test Accuracy ◽  
Household Transmission ◽  
Wide Range ◽  
Test Specificity

AbstractBackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a high risk of transmission in close-contact indoor settings, which may include households. Prior studies have found a wide range of household secondary attack rates and may contain biases due to simplifying assumptions about transmission variability and test accuracy.MethodsWe compiled serological SARS-CoV-2 antibody test data and prior PCR test reporting from members of more than 9000 Utah households. We paired these data with a probabilistic model of household importation and transmission. We calculated a maximum likelihood estimate of the importation probability, mean and variability of household transmission probability, and sensitivity and specificity of test data. Given our household transmission estimates, we estimated the threshold of non-household transmission required for epidemic growth in the population.ResultsWe estimated that individuals in our study households had a 0.38% (95% CI 0.30% – 0.48%) chance of acquiring SARS-CoV-2 infection outside their household. Our household secondary attack rate estimate was 35% (26% – 47%), substantially higher than the crude estimate of 15% unadjusted for imperfect serological test specificity and other factors. We found evidence for high variability in individual transmissibility, with higher probability of no transmissions or many transmissions compared to standard models. With household transmission at our estimates, the average number of non-household transmissions per case must be kept below 0.40 (0.32 – 0.51) to avoid continued growth of the Utah epidemic.ConclusionsOur findings suggest that crude estimates of household secondary attack rate based on serology data without accounting for false positive tests may underestimate the true average transmissibility, even when test specificity is high. Our finding of potential high variability (overdispersion) in transmissibility of infected individuals is consistent with characterizing SARS-CoV-2 transmission being largely driven by superspreading from a minority of infected individuals. Mitigation efforts targeting large households and other locations where many people congregate indoors might curb continued spread of the virus.

scholarly journals Household transmission in people infected with SARS-CoV-2 (COVID-19) in Lima-Perú

2020 ◽  
Author(s):  
Yolanda Angulo-Bazán ◽  
Gilmer Solis-Sánchez ◽  
Joshi Acosta ◽  
Fany Cardenas ◽  
Ana Jorge ◽  
...  
Keyword(s):  
Attack Rate ◽  
Serological Test ◽  
Significant Proportion ◽  
Epidemiological Surveillance ◽  
Primary Case ◽  
Household Transmission ◽  
Surveillance Activity ◽  
Household Members ◽  
Review Study ◽  
Close Contacts

ABSTRACTObjectiveDescribe the characteristics of SARS-CoV-2 infection among household members with a confirmed primary case of COVID-19 in low burden districts in Metropolitan Lima.Materials and MethodsA retrospective, secondary database review study was conducted. The information was collected from an epidemiological surveillance activity in close contacts (co-inhabitants) in 52 households in Metropolitan Lima with only one member with COVID-19. A reevaluation was carried out in 10 households. Epidemiological and clinical variables were evaluated and its association with the result of the rapid serological test (presence of IgG, IgM or both).ResultsSecondary cases were found in 40 households, which represents an average of 49.9% identification per household. A secondary attack rate of 53.0% (125 cases) was found among cohabitants, with 77.6% of cases being symptomatic (symptomatic / asymptomatic ratio: 3.5). The presence of fever and / or chills was found in 40.0% of people with a positive result, followed by a sore throat, in 39.2%. Ageusia and anosmia were present in 22.4% and 20.8% of cases, respectively. A reevaluation in 40 family members 33.6 ± 2.7 days after the first evaluation, show the persistence of positive IgM and IgG in the 20 positive cases in the first evaluation.ConclusionHaving a primary case of COVID-19 in home, the secondary attack rate of this infection is 53%; however, in a significant proportion of households evaluated there was no positive case, beyond the primary case. The epidemiological and clinical characteristics found in this case were in accordance with what has already been reported in other international series.

scholarly journals Household transmission of SARS-CoV-2: a systematic review and meta-analysis of secondary attack rate

2020 ◽  
Author(s):  
Zachary J. Madewell ◽  
Yang Yang ◽  
Ira M. Longini ◽  
M. Elizabeth Halloran ◽  
Natalie E. Dean
Keyword(s):  
Attack Rate ◽  
Index Case ◽  
Close Contact ◽  
Meta Analysis ◽  
Adult Child ◽  
Indoor Environments ◽  
Infected People ◽  
Household Transmission ◽  
Index Cases ◽  
At Home

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spread by direct, indirect, or close contact with infected people via infected respiratory droplets or saliva. Crowded indoor environments with sustained close contact and conversations are a particularly high-risk setting. Methods: We performed a meta-analysis through July 29, 2020 of SARS-CoV-2 household secondary attack rate (SAR), disaggregating by several covariates (contact type, symptom status, adult/child contacts, contact sex, relationship to index case, index case sex, number of contacts in household, coronavirus). Findings: We identified 40 relevant published studies that report household secondary transmission. The estimated overall household SAR was 18.8% (95% confidence interval [CI]: 15.4%-22.2%), which is higher than previously observed SARs for SARS-CoV and MERS-CoV. We observed that household SARs were significantly higher from symptomatic index cases than asymptomatic index cases, to adult contacts than children contacts, to spouses than other family contacts, and in households with one contact than households with three or more contacts. Interpretation: To prevent the spread of SARS-CoV-2, people are being asked to stay at home worldwide. With suspected or confirmed infections referred to isolate at home, household transmission will continue to be a significant source of transmission.

A Transient Single Cylinder Test System for Engine Research and Control Development

2005 ◽  
Author(s):  
John L. Lahti ◽  
Matthew W. Snyder ◽  
John J. Moskwa
Keyword(s):  
Test System ◽  
Intake Manifold ◽  
Test Accuracy ◽  
Test Configuration ◽  
Single Cylinder ◽  
Cylinder Test ◽  
Single Cylinder Engine ◽  
Wide Range ◽  
Reduce Development Time ◽  
High Bandwidth

A transient test system was developed for a single cylinder research engine that greatly improves test accuracy by allowing the single cylinder to operate as though it were part of a multi-cylinder engine. The system contains two unique test components: a high bandwidth transient hydrostatic dynamometer, and an intake airflow simulator. The high bandwidth dynamometer is used to produce a speed trajectory for the single cylinder engine that is equivalent to that produced by a multi-cylinder engine. The dynamometer has high torque capacity and low inertia allowing it to simulate the speed ripple of a multi-cylinder engine while the single cylinder engine is firing. Hardware in loop models of the drivetrain and other components can be used to test the engine as though it were part of a complete vehicle, allowing standardized emissions tests to be run. The intake airflow simulator is a specialized intake manifold that uses solenoid air valves and a vacuum pump to draw air from the manifold plenum in a manner that simulates flow to other engine cylinders, which are not present in the single cylinder test configuration. By regulating this flow from the intake manifold, the pressure in the manifold and the flow through the induction system are nearly identical to that of the multi-cylinder application. The intake airflow simulator allows the intake runner wave dynamics to be more representative of the intended multi-cylinder application because the appropriate pressure trajectory is maintained in the intake manifold plenum throughout the engine cycle. The system is ideally suited for engine control development because an actual engine cylinder is used along with a test system capable of generating a wide range of transient test conditions. The ability to perform transient tests with a single cylinder engine may open up new areas of research exploring combustion and flow under transient conditions. The system can also be used for testing the engine under conditions such as cylinder deactivation, fuel cut-off, and engine restart. The improved rotational dynamics and improved intake manifold dynamics of the test system allow the single cylinder engine to be used for control development and emissions testing early in the engine development process. This can reduce development time and cost because it allows hardware problems to be identified before building more expensive multi-cylinder engines.

Analysis of Thick-Walled Pipeline Elements Operating in Creep Conditions

2015 ◽  
Vol 712 ◽  
pp. 63-68
Author(s):  
Przemysław Osocha ◽  
Bohdan Węglowski
Keyword(s):  
Finite Element ◽  
Test Data ◽  
Creep Test ◽  
Power Plants ◽  
Steam Pressure ◽  
Creep Model ◽  
Creep Process ◽  
Fe Model ◽  
Element Analysis ◽  
Wide Range

In some coal-fired power plants, pipeline elements have worked for over 200 000 hours and increased number of failures is observed. The paper discuses thermal wear processes that take place in those elements and lead to rupture. Mathematical model based on creep test data, and describing creep processes for analyzed material, has been developed. Model has been verified for pipeline operating temperature, lower than tests temperature, basing on Larson-Miller relation. Prepared model has been used for thermal-strength calculations based on a finite element method. Processes taking place inside of element and leading to its failure has been described. Than, basing on prepared mathematical creep model and FE model introduced to Ansys program further researches are made. Analysis of dimensions and shape of pipe junction and its influence on operational element lifetime is presented. In the end multi variable dependence of temperature, steam pressure and element geometry is shown, allowing optimization of process parameters in function of required operational time or maximization of steam parameters. The article presents wide range of methods. The creep test data were recalculated for operational temperature using Larson-Miller parameter. The creep strain were modelled, used equations and their parameters are presented. Analysis of errors were conducted. Geometry of failing pipe junction was introduced to the Ansys program and the finite element analysis of creep process were conducted.

scholarly journals Penile Mondor’s in a Covid-19 patient on prophylactic anti-thrombosis with rivaroxaban: a case report

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Murat Tuğrul Eren ◽  
Hakan Özveri ◽  
Hilal Kurtoğlu
Keyword(s):  
Male Patient ◽  
Antibody Test ◽  
Inflammatory Cells ◽  
Thromboembolism Prophylaxis ◽  
Case Presentation ◽  
Subacute Phase ◽  
Dorsal Vein ◽  
Wide Range ◽  
Underlying Causes

Abstract Background Penile Mondor’s disease (PMD) is thrombophlebitis of the superficial dorsal vein of the penis. Following the occurrence of thrombotic events in the affected veins, the lumen often becomes occluded with fibrin and inflammatory cells. A hyper-coagulative state is one of the underlying causes although most cases of PMD are idiopathic. Coronavirus disease-2019 infection (COVID-19) is associated with frequent thrombotic events. Inflammation and thrombosis play a central role in the course and outcome of COVID-19, which can predispose to both venous and arterial thromboembolism. In this report, we present a 33-year-old male patient diagnosed with PMD during the subacute phase of COVID-19 infection while on prophylactic antithrombotic treatment. Case Presentation A 33-year-old male patient was diagnosed as PMD which occurred during the subacute phase of COVID-19 infection, while he was on active treatment of COVID-19 by prophylactic antithrombotic Rivaroxaban 15 mg therapy and curative antiviral medication. There was no recent sexual intercourse or trauma to the genitals. His PCR test for COVID-19 had become negative, and antibody test was positive at the time of his PMD’s onset. Rivaroxaban was replaced by Enoxaparin (8000 IU/0.8 ml.), a low molecular weight heparin administered subcutaneously and twice daily. On the third day of this medication, all coagulative measurements returned to normal. PMD disappeared in the second week. Conclusion Low-dose Rivaroxaban 15 mg is not safe for some COVID-19-associated thromboembolism prophylaxis, and careful follow-up is critical due to the possibility of a wide range of pathologic thrombotic manifestations in COVID-19 infection.

Use of Functional Response Modeling to Evaluate the Effect of Temperature on Predation of Amblyseius swirskii (Acari: Phytoseiidae) Adults Preying on Tetranychus urticae (Acari: Tetranychidae) Nymphs

2021 ◽  
Author(s):  
Azadeh Farazmand ◽  
Masood Amir-Maafi
Keyword(s):  
Functional Response ◽  
Tetranychus Urticae ◽  
Attack Rate ◽  
Handling Time ◽  
Effect Of Temperature ◽  
Coefficient Of Determination ◽  
Temperature Threshold ◽  
Amblyseius Swirskii ◽  
Functional Responses ◽  
Wide Range

Abstract In this research, functional responses of Amblyseius swirskii Athias-Henriot preying on different Tetranychus urticae Koch nymphal densities (2, 4, 8, 16, 32, 64, and 128) were studied at eight constant temperatures (15, 20, 25, 27.5, 30, 32.5, 35 and 37.5°C) in a circular Petri dish (3-cm diameter × 1-cm height) under lab conditions. At all temperatures, the logistic regression showed a type II functional response. A nonlinear relationship was found between temperature and attack rate and the reciprocal of handling time. The reciprocal of handling time decreased exponentially with increasing temperature. In contrast, the attack rate grew rapidly with increasing temperatures up to an optimum, showing a decreasing trend at higher temperatures. In order to quantify the functional response of A. swirskii over a broad range of temperatures and to gain a better estimation of attack rate and handling time, a temperature-settled functional response equation was suited to our data. Our model showed that the number of prey consumed increased with rising prey density. Also, the predation rates increased with increasing temperatures but decreased at extremely high temperatures. Based on our model, the predation rate begins at the lower temperature threshold (11.73°C) and reaches its peak at upper temperature threshold (29.43°C). The coefficient of determination (R2) of the random predator model was 0.99 for all temperatures. The capability of A. swirskii to search and consume T. urticae over a wide range of temperatures makes it a good agent for natural control of T. urticae in greenhouses.

Abrasion and Wear of Rubber. Analysis of Wear Curves

1952 ◽  
Vol 25 (1) ◽  
pp. 107-109
Author(s):  
J. M. Buist
Keyword(s):  
Mathematical Method ◽  
Test Data ◽  
Wear Test ◽  
Broad Application ◽  
Rubber Industry ◽  
Wide Range ◽  
Subsequent Discussion ◽  
Abrasion Testing ◽  
Wear Index

Abstract One of the difficulties of assessing wear test data of rubber articles, e.g., tires, soles and heels, etc., is the fact that the wear index is not necessarily constant throughout the wearing trial. In a previous publication it was suggested that before exact correlations could be established between laboratory and service tests some mathematical method of obtaining constant indexes for both tests must be found. In the subsequent discussion of this paper at Birmingham, the author revealed that wear curves obtained on the Martindale abrasion tester and also some actual road wear curves could be expressed satisfactorily by an equation of the type y=axn. Since that time further work has been done, and it is now proved that if wear curves obtained on a wide range of laboratory machines, e.g., Martindale, du Pont, and Dunlop (Lambourn), are plotted, these curves are all of the same family y=axn. Although this equation is purely empirical, it is of considerable interest to the rubber industry in that it has such a broad application in the field of laboratory abrasion testing and also in service wear trials.

scholarly journals COVID-19-related pneumonia with a predominant lymphocyte fraction in bronchoalveolar lavage fluid

2021 ◽  
Author(s):  
Tsukasa Ueda ◽  
Taro Yoneda ◽  
Hayato Koba ◽  
Hiroko Morita ◽  
Kazuyuki Kakeshita ◽  
...  
Keyword(s):  
Bronchoalveolar Lavage ◽  
Bronchoalveolar Lavage Fluid ◽  
Close Contact ◽  
Antibody Test ◽  
Lavage Fluid ◽  
Positive Antibody ◽  
Lymphocyte Fraction

A 48-year-old woman, considered as a close contact of her husband who was diagnosed with COVID-19. She was clinically diagnosed with COVID-19-related pneumonia because of a positive antibody test. Her BALF contained an elevated lymphocyte fraction, which might explain why steroids are effective against COVID-19-related pneumonia.

scholarly journals Point-of-care serological assays for SARS-CoV-2 in a UK hospital population: potential for enhanced case finding

2020 ◽  
Author(s):  
Scott Pallett ◽  
Aatish Patel ◽  
Gary Davies ◽  
Luke Moore
Keyword(s):  
Test Performance ◽  
Serological Test ◽  
Point Of Care ◽  
Rapid Test ◽  
Antibody Test ◽  
Preliminary Evaluation ◽  
Hospital Inpatient ◽  
Case Identification ◽  
Global Pandemic ◽  
Population Potential

Abstract Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic, causing over 3,600,000 reported cases and 250,000 deaths worldwide.1 Case identification has predominantly been made by real-time polymerase chain reaction (PCR) during the acute phase and largely restricted to healthcare laboratories. Serological assays are emerging but independent validation is urgently required to assess their utility. Where a plurality of point-of-care (POC) SARS-CoV-2 antibody test kits have become available, we will therefore aim to evaluate a range of kits against the current available gold-standard diagnostic test of PCR in an initial, exploratory study. We will then proceed to carry out testing with 200 hospital inpatients using the OrientGene COVID-19 IgG/IgM Rapid Test Cassette against PCR in order to undergo a preliminary evaluation of POC serological test performance characteristics within a hospital inpatient cohort.

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