scholarly journals Shrinkage in serial intervals across cluster transmission generations of COVID-19

2020 ◽  
Author(s):  
Shi Zhao ◽  
Yu Zhao ◽  
Biao Tang ◽  
Daozhou Gao ◽  
Zhao Guo ◽  
...  
Keyword(s):  
Hong Kong ◽  
Probability Distribution ◽  
Global Health ◽  
Contact Tracing ◽  
Epidemiological Factors ◽  
Transmission Process ◽  
Serial Interval ◽  
Speed Up ◽  
Population Scale ◽  
The Individual

The COVID-19 pandemic poses a serious threat to global health, and one of the key epidemiological factors that shape the transmission of COVID-19 is its serial interval (SI). Although SI is commonly considered following a probability distribution at a population scale, slight discrepancies in SI across different transmission generations are observed from the aggregated statistics in recent studies. To explore the change in SI across transmission generations, we develop a likelihood-based statistical inference framework to examine and quantify the change in SI. The COVID-19 contact tracing surveillance data in Hong Kong are used for exemplification. We find that the individual SI of COVID-19 is likely to shrink with a rate of 0.72 per generation and 95%CI: (0.54, 0.96) as the transmission generation increases. We speculate that the shrinkage in SI is an outcome of competition among multiple candidate infectors within a cluster of cases. The shrinkage in SI may speed up the transmission process, and thus the nonpharmaceutical interventive strategies are crucially important to mitigate the COVID-19 epidemic.

scholarly journals Estimating the serial interval of the novel coronavirus disease (COVID-19): A statistical analysis using the public data in Hong Kong from January 16 to February 15, 2020

2020 ◽  
Author(s):  
Shi Zhao ◽  
Daozhou Gao ◽  
Zian Zhuang ◽  
Marc KC Chong ◽  
Yongli Cai ◽  
...  
Keyword(s):  
Hong Kong ◽  
Contact Tracing ◽  
Distributed Model ◽  
Serial Interval ◽  
Public Data ◽  
Interval Censored ◽  
Large Outbreak ◽  
Emerging Virus ◽  
Novel Coronavirus ◽  
Censored Likelihood

AbstractBackgroundsThe emerging virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a large outbreak of novel coronavirus disease (COVID-19) in Wuhan, China since December 2019. Based on the publicly available surveillance data, we identified 21 transmission chains in Hong Kong and estimated the serial interval (SI) of COVID-19.MethodsIndex cases were identified and reported after symptoms onset, and contact tracing was conducted to collect the data of the associated secondary cases. An interval censored likelihood framework is adopted to fit a Gamma distribution function to govern the SI of COVID-19.FindingsAssuming a Gamma distributed model, we estimated the mean of SI at 4.4 days (95%CI: 2.9−6.7) and SD of SI at 3.0 days (95%CI: 1.8−5.8) by using the information of all 21 transmission chains in Hong Kong.ConclusionThe SI of COVID-19 may be shorter than the preliminary estimates in previous works. Given the likelihood that SI could be shorter than the incubation period, pre-symptomatic transmission may occur, and extra efforts on timely contact tracing and quarantine are recommended in combating the COVID-19 outbreak.

scholarly journals Estimating the protective effect of case isolation with transmission tree reconstruction during the Ebola outbreak in Nigeria, 2014

2020 ◽  
Vol 17 (169) ◽  
pp. 20200498
Author(s):  
Yat Hin Chan ◽  
Hiroshi Nishiura
Keyword(s):  
Protective Effect ◽  
Reproduction Number ◽  
Credible Interval ◽  
Hospitalization Rate ◽  
Contact Tracing ◽  
Transmission Network ◽  
Tree Reconstruction ◽  
Serial Interval ◽  
Formed Part ◽  
The Individual

The mainstream interventions used during the 2014–2016 Ebola epidemic were contact tracing and case isolation. The Ebola outbreak in Nigeria that formed part of the 2014–2016 epidemic demonstrated the effectiveness of control interventions with a 100% hospitalization rate. Here, we aim to explicitly estimate the protective effect of case isolation, reconstructing the time events of onset of illness and hospitalization as well as the transmission network. We show that case isolation reduced the reproduction number and shortened the serial interval. Employing Bayesian inference with the Markov chain Monte Carlo method for parameter estimation and assuming that the reproduction number exponentially declines over time, the protective effect of case isolation was estimated to be 39.7% (95% credible interval: 2.4%–82.1%). The individual protective effect of case isolation was also estimated, showing that the effectiveness was dependent on the speed, i.e. the time from onset of illness to hospitalization.

scholarly journals Subcritical Transmission in the Early Stage of COVID-19 in Korea

2021 ◽  
Vol 18 (3) ◽  
pp. 1265
Author(s):  
Yong Sul Won ◽  
Jong-Hoon Kim ◽  
Chi Young Ahn ◽  
Hyojung Lee
Keyword(s):  
Incubation Period ◽  
Early Stage ◽  
Probability Distributions ◽  
Likelihood Estimation ◽  
Contact Tracing ◽  
Statistical Characterization ◽  
Serial Interval ◽  
Imported Cases ◽  
The Mean ◽  
Reporting Delays

While the coronavirus disease 2019 (COVID-19) outbreak has been ongoing in Korea since January 2020, there were limited transmissions during the early stages of the outbreak. In the present study, we aimed to provide a statistical characterization of COVID-19 transmissions that led to this small outbreak. We collated the individual data of the first 28 confirmed cases reported from 20 January to 10 February 2020. We estimated key epidemiological parameters such as reporting delay (i.e., time from symptom onset to confirmation), incubation period, and serial interval by fitting probability distributions to the data based on the maximum likelihood estimation. We also estimated the basic reproduction number (R0) using the renewal equation, which allows for the transmissibility to differ between imported and locally transmitted cases. There were 16 imported and 12 locally transmitted cases, and secondary transmissions per case were higher for the imported cases than the locally transmitted cases (nine vs. three cases). The mean reporting delays were estimated to be 6.76 days (95% CI: 4.53, 9.28) and 2.57 days (95% CI: 1.57, 4.23) for imported and locally transmitted cases, respectively. The mean incubation period was estimated to be 5.53 days (95% CI: 3.98, 8.09) and was shorter than the mean serial interval of 6.45 days (95% CI: 4.32, 9.65). The R0 was estimated to be 0.40 (95% CI: 0.16, 0.99), accounting for the local and imported cases. The fewer secondary cases and shorter reporting delays for the locally transmitted cases suggest that contact tracing of imported cases was effective at reducing further transmissions, which helped to keep R0 below one and the overall transmissions small.

BioBoard

2006 ◽  
Vol 10 (22) ◽  
pp. 1267-1273
Keyword(s):  
Hong Kong ◽  
New Zealand ◽  
South Korea ◽  
Drug Approval ◽  
Influenza Virus Vaccine ◽  
Biomedical Ethics ◽  
Bird Flu ◽  
H5n1 Avian Influenza Virus ◽  
H5n1 Avian Influenza ◽  
Speed Up

Australia — Politicians Chastise Australia's Science Institute. Australia — GE Healthcare and WA Government Collaborate on Cell-based Imaging Equipment. Australia — The Goal of Imugene's H5N1 Avian Influenza Virus Vaccine. China — East China University Sparks Debate on Education Funding. China — 3D Map of SARS virus Drawn. China — Researchers Comment that Global Loss of Biodiversity is Harming Ocean Bounty. China — China Insists that there are No Variant Bird Flu Strain. China — Gene involved in Eye Lens Development. China — Cancer-causing Dye Found in Duck Eggs in China. Hong Kong — Scientists in Hong Kong Found Clues to Pandemic Bird Flu. Hong Kong — Hong Kong Bird Flu Expert Picked to Head WHO. India — Ranbaxy Signs Licensing Agreement with Swiss Company Debiopharm. India — Indian Biotechnology Park. Japan — Japan's New Premier Chases Innovation. Japan — Japan Reforms Screening to Speed up Drug Approval. New Zealand — New Zealand Invests in Neurology Project. South Korea — South Korea Gives Funding Boost to Stem-Cell Research. South Korea — South Korea Plans to Inject $253 million into Biotech. South Korea — Scientists Discover Stem Cells Might Help to Treat Mental Illness. Singapore — Renowned French Cancer Development Biologist Moves to Singapore's Biopolis. Singapore — Singapore Plans to Build Bigger Heart Center to Handle Spiraling Patient Numbers. Singapore — New Centre for Biomedical Ethics at NUS. Taiwan — Taiwan's CDC Places Order for H5N1 Vaccine. Taiwan — Tenders sought for Pingtung Agricultural Biotech Park Housing.

A Study on Stock-Selection and Market-Timing Performance: Evidence from Hong Kong Mandatory Provident Funds (MPF)

2008 ◽  
Vol 11 (04) ◽  
pp. 617-649 ◽  
Author(s):  
Patrick Kuok-kun Chu ◽  
Michael McKenzie
Keyword(s):  
Hong Kong ◽  
Economic Condition ◽  
Market Timing ◽  
Stock Selection ◽  
Timing Ability ◽  
Conditional Models ◽  
Equity Funds ◽  
The Individual ◽  
Timing Models ◽  
Comprehensive Study

This paper presents the first comprehensive study of the performance and market timing ability of the equity funds that comprise the Hong Kong Mandatory Provident Funds (MPF) scheme. In general, our results suggest that US equity funds consistently underperform relative to the market, while the other fund groups consistently outperform the market. The stock-selection ability of MPF constituent equity funds in times of changing economic condition is also investigated. The evidence is consistent with previous studies, which suggest that the conditional models decrease the individual fund traditional alpha measure. The market timing models of Treynor–Mazuy and Henriksson–Merton provide evidence of superior market timing ability.

Hong Kong’s institutional incongruities and its tourism policy

2015 ◽  
Vol 4 (3) ◽  
pp. 312-329 ◽  
Author(s):  
Chiew Ping Yew
Keyword(s):  
Hong Kong ◽  
Political System ◽  
Central Government ◽  
Institutional Arrangements ◽  
Content Type ◽  
Business Interests ◽  
Tourism Policy ◽  
The Government ◽  
The Individual ◽  
Policy And Planning

Purpose – With a focus on Hong Kong tourism policy, the purpose of this paper is to explain the Hong Kong government’s conundrum in addressing society’s concerns and controversies over the massive influx of mainland tourists in recent years. Design/methodology/approach – This paper adopts the approach of historical institutionalism, in which the notion of structural-power takes centre stage. It outlines some notable trends in Hong Kong’s tourist arrivals and highlights some of the controversies that have arisen before delving into how existing institutional arrangements and key actors have shaped Hong Kong’s tourism policy amid the city’s shifting social, political and economic contexts. Findings – The prevalence of business interests and the ideology of economism largely explain the Hong Kong government’s stasis in tackling the problems stemming from the large inflow of mainland visitors. Institutional arrangements in the post-handover period have further empowered the business class, giving it an edge over the unelected executive that lacks a popular mandate. Therefore, even if the central government has signaled its willingness to adjust the Individual Visit Scheme (IVS) policy, the Hong Kong government is unlikely to propose significant cuts to the inflow of IVS arrivals. Without further political reforms to boost the executive’s legitimacy and accountability to the Hong Kong people, it is doubtful that the government may emerge from its predicament in the near future. Originality/value – Through the lens of tourism policy and planning pertaining to inbound mainland visitors, this paper aims to assess the current state of governance in Hong Kong. It not only offers a timely look into Hong Kong’s political system 17 years after handover but also explores the extent to which apparent dysfunctions in the city’s governance today are a consequence of institutional incongruities in its political system.

scholarly journals A renewal equation model to assess roles and limitations of contact tracing for disease outbreak control

2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Francesca Scarabel ◽  
Lorenzo Pellis ◽  
Nicholas H. Ogden ◽  
Jianhong Wu
Keyword(s):  
Deterministic Model ◽  
Infected Individual ◽  
Equation Model ◽  
Renewal Equation ◽  
Contact Tracing ◽  
Calendar Time ◽  
Individual Level ◽  
Total Incidence ◽  
Community Transmission ◽  
The Individual

We propose a deterministic model capturing essential features of contact tracing as part of public health non-pharmaceutical interventions to mitigate an outbreak of an infectious disease. By incorporating a mechanistic formulation of the processes at the individual level, we obtain an integral equation (delayed in calendar time and advanced in time since infection) for the probability that an infected individual is detected and isolated at any point in time. This is then coupled with a renewal equation for the total incidence to form a closed system describing the transmission dynamics involving contact tracing. We define and calculate basic and effective reproduction numbers in terms of pathogen characteristics and contact tracing implementation constraints. When applied to the case of SARS-CoV-2, our results show that only combinations of diagnosis of symptomatic infections and contact tracing that are almost perfect in terms of speed and coverage can attain control, unless additional measures to reduce overall community transmission are in place. Under constraints on the testing or tracing capacity, a temporary interruption of contact tracing may, depending on the overall growth rate and prevalence of the infection, lead to an irreversible loss of control even when the epidemic was previously contained.

scholarly journals Implantação de Terapia Comunitária online: tecnologia do cuidado em tempos de pandemia

2020 ◽  
Vol 16 (esp. 1) ◽  
pp. 393-408
Author(s):  
André Luiz Pereira Silva ◽  
Doralice Otaviano ◽  
Fernanda Cruz Vieira Ferreira ◽  
Jurema Valkiria Otaviano ◽  
Jussara Otaviano ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Mental Health ◽  
Global Health ◽  
Social Determinants Of Health ◽  
Social Determinants ◽  
Health Crisis ◽  
The Social ◽  
The Individual ◽  
Psychosocial Crisis

Suddenly in March 2020 we found ourselves confined and isolated in our homes, due to a global health crisis arising from a pandemic, caused by the contamination of a virus called COVID-19. This health crisis also generated a crisis in the social determinants of health, especially those related to the economy, education and culture. But it also generated another crisis, the psychosocial crisis, where populations affected by the effects of mental damage caused by the pandemic and isolation, showed important signs of stress. It is in this scenario that the Integrative Community Therapy, previously carried out in person, is renewed and reinvented. This article reports on the experience of implementing the Integrative Community Therapy online in Brazil and presents the results of the Afinando Vidas Pole in the contribution of improving the quality of life and the individual and collective mental health of the Brazilian population.

Rapid and Efficient Wet Fixation by the Use of Steam

1969 ◽  
Vol 39 (6) ◽  
pp. 497-504 ◽  
Author(s):  
Norman R. S. Hollies ◽  
Steven R. Chafitz ◽  
Karen A. Farquhar
Keyword(s):  
Fiber Surface ◽  
Strong Acid ◽  
Strength Properties ◽  
Fiber System ◽  
Resin Solution ◽  
Speed Up ◽  
Drying Properties ◽  
The Individual ◽  
Time Required ◽  
Finishing Processes

The impregnation of cotton fabrics with a solution consisting of strong acid and a combination of N-methylol resins having polymer-forming and cross-linking properties distinguishes the wet-fixation system from conventional durable-press processes, and this finish results in an improved balance of smoothness and strength properties during wear and laundering. Swelling of the fibers in a steam atmosphere, following padding in the resin solution can serve to speed up the impregnation process. In addition, with controls to minimize resin migration back to the fiber surface, steaming can substantially improve the efficiency of the use of resin for producing these smooth drying properties. The degree of penetration of resin is influenced by a number of process variables, such as predrying before steaming, steaming time, fabric tension and rapidity of neutralization. The optimum in fabric performance is achieved with both sufficient resin of both types in the fiber system and even distribution of resin within the individual fibers, Steaming acts to improve both these factors over that achieved in conventional hot wet fixation and so reduces the time required for wet fixation by a factor of 20–30. There is a corresponding increase in efficiency of resin use so that resin solids in the bath can be reduced two- to three-fold. These findings appear to have general application to a variety of cotton finishing processes involving fiber impregnation with reactive resins.

scholarly journals Estimation of incubation period and serial interval of COVID-19: analysis of 178 cases and 131 transmission chains in Hubei province, China

2020 ◽  
Vol 148 ◽  
Author(s):  
Lin Yang ◽  
Jingyi Dai ◽  
Jun Zhao ◽  
Yunfu Wang ◽  
Pingji Deng ◽  
...  
Keyword(s):  
Incubation Period ◽  
Failure Time ◽  
Age Groups ◽  
Hubei Province ◽  
Interval Censoring ◽  
Contact Tracing ◽  
Considerable Proportion ◽  
Outbreak Period ◽  
Serial Interval ◽  
Incubation Periods

Abstract A novel coronavirus disease, designated as COVID-19, has become a pandemic worldwide. This study aims to estimate the incubation period and serial interval of COVID-19. We collected contact tracing data in a municipality in Hubei province during a full outbreak period. The date of infection and infector–infectee pairs were inferred from the history of travel in Wuhan or exposed to confirmed cases. The incubation periods and serial intervals were estimated using parametric accelerated failure time models, accounting for interval censoring of the exposures. Our estimated median incubation period of COVID-19 is 5.4 days (bootstrapped 95% confidence interval (CI) 4.8–6.0), and the 2.5th and 97.5th percentiles are 1 and 15 days, respectively; while the estimated serial interval of COVID-19 falls within the range of −4 to 13 days with 95% confidence and has a median of 4.6 days (95% CI 3.7–5.5). Ninety-five per cent of symptomatic cases showed symptoms by 13.7 days (95% CI 12.5–14.9). The incubation periods and serial intervals were not significantly different between male and female, and among age groups. Our results suggest a considerable proportion of secondary transmission occurred prior to symptom onset. And the current practice of 14-day quarantine period in many regions is reasonable.

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