Pre-symptomatic Incubation Model for Precision Strategies of Screening, Quarantine, and Isolation of Imported COVID-19 Cases: Modelling Approach (Preprint)

2021 ◽  
Author(s):  
Grace Hsiao-Hsuan Jen ◽  
Amy Ming-Fang Yen ◽  
Cheng-Yang Hsu ◽  
Harold Sjursen ◽  
Sam Li-Sheng Chen ◽  
...  
Keyword(s):  
Control Strategies ◽  
Herd Immunity ◽  
Border Control ◽  
Rt Pcr ◽  
Dwelling Time ◽  
Symptomatic Disease ◽  
Optimal Interval ◽  
The Third ◽  
Specific Risk ◽  
Country Specific

BACKGROUND Pre-symptomatic imported COVID-19 cases play an important role in border control strategies for containing their further spread to community outbreaks. OBJECTIVE A pre-symptomatic incubation model was proposed to develop precision screening, quarantine, and isolation strategies for containing imported COVID-19 case. METHODS The natural history model of pre-symptomatic and symptomatic COVID-19 was constructed by using 727 imported cases of COVID-19 in Taiwan, consisting of the first pandemic period (March-June), the second containment period (July-September), and the third pandemic period (October-December) in parallel with the evolution of new virus variants. We collected the valuable information on symptomatic cases ascertained upon the arrival and the natural transition from pre-symptomatic RT-PCR detectable phase (RT-PCRDP) to symptomatic phase during 14-day quarantine period. We estimated the incidence of pre-symptomatic disease and the dwelling time from pre-symptomatic RT-PCRDP to symptomatic phase on which we were based to simulate various strategies of screening with RT-PCR test and the optimal interval of quarantine and isolation for the vaccinated and unvaccinated travelers. RESULTS The overall daily rate (per 100,000) of pre-symptomatic COVID-19 cases was 106 (95% CI: 95-118) in the first period (March-June), fell to 37 (95% CI: 27.9-47.2) in the second period (July-September), and resurged to 141 (95% CI: 117-164) in the third period (October-December). Given the median dwelling time, over 82% of the transition from pre-symptomatic to symptomatic phase were noted in 5-day quarantine. The length of quarantine given two tests can be reduced from 14 to 5 days for the unvaccinated traveler. It can be precisely determined by the classification of country-specific risk and may be reduced to two days or lifting, depending on country-specific risk, after vaccination. CONCLUSIONS Precision strategies for imported COVID-19 cases provide a solution to the trade-off between border control and re-opening to travel before vaccination to reach herd immunity worldwide.

scholarly journals Computing a Lower Bound for the Total Size of the COVID-19 Infected Population Iceberg Using the General Age-Group Distribution

2021 ◽  
Author(s):  
Yuval Shahar ◽  
Osnat Mokryn
Keyword(s):  
Lower Bound ◽  
Herd Immunity ◽  
Rt Pcr ◽  
Total Size ◽  
Susceptibility To Infection ◽  
Total Prevalence ◽  
Asymptomatic Individuals ◽  
The Uk ◽  
Group Distribution ◽  
Country Specific

The COVID-19 pandemic has raised questions regarding the total prevalence of infection, referred to as the (Infection) Iceberg. Accurate estimates of country-specific Iceberg sizes support better pandemic monitoring, evaluation of proximity to herd immunity, estimation of infection fatality rates (IFRs), and assessment of risks due to infection by asymptomatic individuals. Previous suggestions included surveying the population for COVID-19 symptoms, and a few countries performed randomized serological testing. We suggest a new method for setting a lower bound on the Iceberg size, by finding the Pivot group, the population sub-group with the highest relative risk for being confirmed as positively infected in the RT-PCR test. We differentiate between susceptibility to infection, which we assume to be uniform across all population sub-groups, and susceptibility to developing symptoms and complications, which may differ between sub-group. Our key assumption is that the Pivot sub-group's proportion within the infected Iceberg is similar to its proportion within the population (or even lower). We compute the minimal Iceberg Factor that allows for a sufficient number of people from the Pivot sub-group within the presumed Iceberg to explain the portion of the Pivot group that is confirmed positive, and also the minimal Iceberg Factor when allowing for a statistically insignificant deviation from the population's Pivot group proportion. We demonstrate, using the UK and Spain serological surveys, that our key assumption holds, and that the actual Iceberg factors fit our predictions. We compute minimal Iceberg factors, and when possible, assessed IFRs and serology-based IFRs, for nine countries.

scholarly journals Estimating asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan: a mathematical modeling study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xi Huo ◽  
Jing Chen ◽  
Shigui Ruan
Keyword(s):  
Disease Transmission ◽  
Large Scale ◽  
Transmission Rate ◽  
Control Strategies ◽  
Herd Immunity ◽  
Antibody Prevalence ◽  
Screening Process ◽  
Vaccination Programs ◽  
Prevalence Level ◽  
The Impact

Abstract Background The COVID-19 outbreak in Wuhan started in December 2019 and was under control by the end of March 2020 with a total of 50,006 confirmed cases by the implementation of a series of nonpharmaceutical interventions (NPIs) including unprecedented lockdown of the city. This study analyzes the complete outbreak data from Wuhan, assesses the impact of these public health interventions, and estimates the asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan. Methods By taking different stages of the outbreak into account, we developed a time-dependent compartmental model to describe the dynamics of disease transmission and case detection and reporting. Model coefficients were parameterized by using the reported cases and following key events and escalated control strategies. Then the model was used to calibrate the complete outbreak data by using the Monte Carlo Markov Chain (MCMC) method. Finally we used the model to estimate asymptomatic and undetected cases and approximate the overall antibody prevalence level. Results We found that the transmission rate between Jan 24 and Feb 1, 2020, was twice as large as that before the lockdown on Jan 23 and 67.6% (95% CI [0.584,0.759]) of detectable infections occurred during this period. Based on the reported estimates that around 20% of infections were asymptomatic and their transmission ability was about 70% of symptomatic ones, we estimated that there were about 14,448 asymptomatic and undetected cases (95% CI [12,364,23,254]), which yields an estimate of a total of 64,454 infected cases (95% CI [62,370,73,260]), and the overall antibody prevalence level in the population of Wuhan was 0.745% (95% CI [0.693%,0.814%]) by March 31, 2020. Conclusions We conclude that the control of the COVID-19 outbreak in Wuhan was achieved via the enforcement of a combination of multiple NPIs: the lockdown on Jan 23, the stay-at-home order on Feb 2, the massive isolation of all symptomatic individuals via newly constructed special shelter hospitals on Feb 6, and the large scale screening process on Feb 18. Our results indicate that the population in Wuhan is far away from establishing herd immunity and provide insights for other affected countries and regions in designing control strategies and planing vaccination programs.

scholarly journals COVID-19 and pregnancy – where are we now? A review

2020 ◽  
Vol 48 (5) ◽  
pp. 428-434 ◽  
Author(s):  
Aleksandra Rajewska ◽  
Wioletta Mikołajek-Bedner ◽  
Joanna Lebdowicz-Knul ◽  
Małgorzata Sokołowska ◽  
Sebastian Kwiatkowski ◽  
...  
Keyword(s):  
Case Fatality ◽  
Fetal Distress ◽  
Delivery Mode ◽  
Test Results ◽  
Rt Pcr ◽  
Third Trimester ◽  
The Third ◽  
Laboratory Test Results ◽  
Protective Antibodies ◽  
Polymerase Chain

AbstractThe new acute respiratory disease severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is highly contagious. It has caused many deaths, despite a relatively low general case fatality rate (CFR). The most common early manifestations of infection are fever, cough, fatigue and myalgia. The diagnosis is based on the exposure history, clinical manifestation, laboratory test results, chest computed tomography (CT) findings and a positive reverse transcription-polymerase chain reaction (RT-PCR) result for coronavirus disease 2019 (COVID-19). The effect of SARS-CoV-2 on pregnancy is not already clear. There is no evidence that pregnant women are more susceptible than the general population. In the third trimester, COVID-19 can cause premature rupture of membranes, premature labour and fetal distress. There are no data on complications of SARS-CoV-2 infection before the third trimester. COVID-19 infection is an indication for delivery if necessary to improve maternal oxygenation. Decision on delivery mode should be individualised. Vertical transmission of coronavirus from the pregnant woman to the fetus has not been proven. As the virus is absent in breast milk, the experts encourage breastfeeding for neonatal acquisition of protective antibodies.

scholarly journals Prevalence of SARS-CoV-2 Infection at the University of Barcelona during the Third COVID-19 Pandemic Wave in Spain

2021 ◽  
Vol 18 (12) ◽  
pp. 6526
Author(s):  
Sebastián Videla ◽  
Aurema Otero ◽  
Sara Martí ◽  
M. Ángeles Domínguez ◽  
Nuria Fabrellas ◽  
...  
Keyword(s):  
Ad Hoc ◽  
Venous Blood ◽  
Herd Immunity ◽  
Cross Sectional Study ◽  
Rt Pcr ◽  
Igg Antibody ◽  
Cross Sectional ◽  
Total Prevalence ◽  
The University ◽  
The Impact

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic started in December 2019 and still is a major global health challenge. Lockdown measures and social distancing sparked a global shift towards online learning, which deeply impacted universities’ daily life, and the University of Barcelona (UB) was not an exception. Accordingly, we aimed to determine the impact of the SARS-CoV-2 pandemic at the UB. To that end, we performed a cross-sectional study on a sample of 2784 UB members (n = 52,529). Participants answered a brief, ad hoc, online epidemiological questionnaire and provided a nasal swab for reverse transcription polymerase chain reaction (RT-PCR) SARS-CoV-2 analysis and a venous blood sample for SARS-CoV-2 IgG antibody assay. Total prevalence of SARS-CoV-2 infection (positive RT-PCR or positive IgG) was 14.9% (95%CI 13.3 to 17.0%). Forty-four participants (1.6%, 95%CI: 1.2–2.1%) were positive for SARS-CoV-2 RT-PCR. IgG against SARS-CoV-2 was observed in 12.8% (95%CI: 11.6–14.1%) of participants. Overall, while waiting for population vaccination and/or increased herd immunity, we should concentrate on identifying and isolating new cases and their contacts.

scholarly journals Biological and Molecular Characteristics of a Novel Partitivirus Infecting the Edible Fungus Lentinula edodes

Plant Disease ◽  
2017 ◽  
Vol 101 (5) ◽  
pp. 726-733 ◽  
Author(s):  
Mengpei Guo ◽  
Yinbing Bian ◽  
Jinjie Wang ◽  
Gangzheng Wang ◽  
Xiaolong Ma ◽  
...  
Keyword(s):  
Lentinula Edodes ◽  
Control Strategies ◽  
Phylogenetic Analyses ◽  
Pcr Analysis ◽  
Molecular Characteristics ◽  
Rt Pcr ◽  
Edible Fungus ◽  
Qpcr Analysis ◽  
Disease Diagnostics ◽  
Wild Strains

A new partitivirus named Lentinula edodes partitivirus 1 (LePV1) was isolated from a diseased L. edodes strain with severe degeneration of the mycelium and imperfect browning in bag cultures. The nucleotide sequences of LePV1 dsRNA-1 and dsRNA-2 were determined; they were 2,382 bp and 2,245 bp in length, and each contained a single ORF encoding RNA-dependent RNA polymerase (RdRp) and coat protein (CP), respectively. The purified virus preparation contained isometric particles 34 nm in diameter encapsidating these dsRNAs. Phylogenetic analyses showed LePV1 to be a new member of Betapartitivirus, with the RdRp sequence most closely related to Grapevine partitivirus. RT-PCR analysis showed that 27 of the 56 Chinese L. edodes core collection strains carry LePV1, with the virus being more common in wild strains than cultivated strains. In addition, qPCR analysis suggested that coinfection with L. edodes mycovirus HKB (LeV-HKB) could increase replication of the RdRp gene of LePV1. This study may be essential for the development of more accurate disease diagnostics and the formulation of control strategies for viral diseases in L. edodes.

scholarly journals Impact of COVID-19 Variants on the Second Wave in India and Subsequent Discretion of Possibilities of the Third Wave

2021 ◽  
pp. 115-126
Author(s):  
Sudarshan Ramaswamy ◽  
Meera Dhuria ◽  
Sumedha M. Joshi ◽  
Deepa H Velankar
Keyword(s):  
Herd Immunity ◽  
Sir Model ◽  
The Other ◽  
Third Wave ◽  
Focal Points ◽  
Current Analysis ◽  
The Third ◽  
The Impact ◽  
Second Wave ◽  
Insight Into

Introduction: Epidemiological comprehension of the COVID-19 situation in India can be of great help in early prediction of any such indications in other countries and possibilities of the third wave in India as well. It is essential to understand the impact of variant strains in the perspective of the rise in daily cases during the second wave – Whether the rise in cases witnessed is due to the reinfections or the surge is dominated by emergence of mutants/variants and reasons for the same. Overall objective of this study is to predict early epidemiological indicators which can potentially lead to COVID-19 third wave in India. Methodology: We analyzed both the first and second waves of COVID-19 in India and using the data of India’s SARS-CoV-2 genomic sequencing, we segregated the impact of the Older Variant (OV) and the other major variants (VOI / VOC).  Applying Kermack–McKendrick SIR model to the segregated data progression of the epidemic in India was plotted in the form of proportion of people infected. An equation to explain herd immunity thresholds was generated and further analyzed to predict the possibilities of the third wave. Results: Considerable difference in ate of progression of the first and second wave was seen. The study also ascertains that the rate of infection spread is higher in Delta variant and is expected to have a higher threshold (>2 times) for herd immunity as compared to the OV. Conclusion: Likelihood of the occurrence of the third wave seems unlikely based on the current analysis of the situation, however the possibilities cannot be ruled out. Understanding the epidemiological details of the first and second wave helped in understanding the focal points responsible for the surge in cases during the second wave and has given further insight into the future.

scholarly journals SARS-CoV-2 re-positivity within the first 3 months of COVID-19 recovery; probable re-infection

2021 ◽  
Author(s):  
sara sadr ◽  
Melika Arab Bafrani ◽  
Alireza Abdollahi ◽  
SeyedAhmad SeyedAlinaghi ◽  
Esmaeil Mohammadnejad ◽  
...  
Keyword(s):  
Herd Immunity ◽  
Rt Pcr ◽  
Complete Protection ◽  
Genetic Sequencing ◽  
Serum Igg ◽  
Follow Up Studies ◽  
Positive Results

Objectives Possibility of reinfection with SARS-CoV-2 changes our view on herd immunity and vaccination, and can impact worldwide quarantine policies. We performed RT-PCR follow-up studies on recovered patients to assess possible development of reinfections and re-positivity. Method During a 6-month period, 202 PCR-confirmed recovering COVID-19 patients entered this study. Follow-up RT-PCR tests and symptoms assessment were performed one month after the initial Positive results. patients who tested negative were tested again one and three months later. The Serum IgG and IgM levels were measured in the last follow-up session. Results In the first two follow-up sessions, 82 patients continued their participation, of which four patients tasted positive. In the second follow-up 44 patients participated, three of whom tested positive. None of the patients who tested positive in the first and second follow-up session were symptomatic. In the last session, 32 patients were tested and four patients were positive, three of them were mildly symptomatic and all of them were positive for IgG. Conclusion A positive RT-PCR in a recovering patient may represent reinfection. While we did not have the resources to prove reinfection by genetic sequencing of the infective viruses, we believe presence of mild symptoms in the three patients who tested positive over 100 days after becoming asymptomatic, can be diagnosed as reinfection. The IgG may have abated the symptoms of the reinfection, without providing complete protection.

scholarly journals Interferometer Sensing and Control for the Advanced Virgo Experiment in the O3 Scientific Run

Galaxies ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 85
Author(s):  
Annalisa Allocca ◽  
Diego Bersanetti ◽  
Julia Casanueva Diaz ◽  
Camilla De Rossi ◽  
Maddalena Mantovani ◽  
...  
Keyword(s):  
Gravitational Waves ◽  
Laser Interferometer ◽  
Control Strategies ◽  
New Techniques ◽  
Binary Neutron Star ◽  
2Nd Generation ◽  
The Third ◽  
Binary Black Hole ◽  
One Year ◽  
And Control

Advanced Virgo is a 2nd-generation laser interferometer based in Cascina (Italy) aimed at the detection of gravitational waves (GW) from astrophysical sources. Together with the two USA-based LIGO interferometers they constitute a network which operates in coincidence. The three detectors observed the sky simultaneously during the last part of the second Observing Run (O2) in August 2017, and this led to two paramount discoveries: the first three-detector observation of gravitational waves emitted from the coalescence of a binary black hole system (GW170814), and the first detection ever of gravitational waves emitted from the coalescence of a binary neutron star system (GW170817). Coincident data taking was re-started for the third Observing Run (O3), which started on 1st April 2019 and lasted almost one year. This paper will describe the new techniques implemented for the longitudinal controls with respect to the ones already in use during O2. Then, it will present an extensive description of the full scheme of the angular controls of the interferometer, focusing on the different control strategies that are in place in the different stages of the lock acquisition procedure, which is the complex sequence of operations by which an uncontrolled, “free” laser interferometer is brought to the final working point, which allows the detector to reach the best sensitivity.

The monocyte transcriptome during pregnancy in multiple sclerosis: prominent expression of the Fc-receptor CD64

2010 ◽  
Vol 17 (4) ◽  
pp. 389-396 ◽  
Author(s):  
Rinze F Neuteboom ◽  
Evert Verbraak ◽  
Annet F Wierenga-Wolf ◽  
Jane SA Voerman ◽  
Marjan van Meurs ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Cell Signalling ◽  
Immune Functions ◽  
Rt Pcr ◽  
Third Trimester ◽  
Fc Gamma Receptor ◽  
The Third ◽  
Gamma Receptor ◽  
Genes Expression ◽  
Biological Interest

Background: During the third trimester of pregnancy multiple sclerosis (MS) disease activity is reduced. It is not fully understood which factors mediate this disease amelioration.Objective: To study alterations of the monocyte transcriptome during pregnancy in MS patients, using a genomewide approach to identify differentially regulated genes.Methods: Women with MS and healthy controls were longitudinally studied, including a visit before pregnancy.Results: RNA-microarray analysis was performed in six patients. We found a significant increase of CD64 (Fc gamma receptor 1a, FcgR1a) during the third trimester compared with baseline, confirmed by RT-PCR in a group of ten patients. Analysis with Ingenuity software was performed using all genes expression of which was altered at least 1.5-fold in at least five out of six patients. Major networks that were altered during MS pregnancy were: cell-to-cell signalling and interaction, immune response, and cell signalling. From the genes selected for Ingenuity analysis, seven additional candidate genes, selected for their biological interest, were tested using RT-PCR in ten patients with MS and nine controls. We found an increased expression of JAK2 and STAT1 directly postpartum in patients with MS and in controls.Conclusion: The increased CD64 expression during pregnancy is indicative of enhanced innate immune functions.

Sign in / Sign up

Export Citation Format

Share Document