scholarly journals A spatial and dynamic solution for allocation of COVID-19 vaccines when supply is limited

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Wenzhong Shi ◽  
Chengzhuo Tong ◽  
Anshu Zhang ◽  
Zhicheng Shi
Keyword(s):  
Hong Kong ◽  
Total Population ◽  
Control Measures ◽  
Reproductive Number ◽  
Travel History ◽  
Weighted Kernel ◽  
Risk Areas ◽  
Sporadic Cases ◽  
Vaccine Availability ◽  
Global Population

Abstract Background Since most of the global population needs to be vaccinated to reduce COVID-19 transmission and mortality, a shortage of COVID-19 vaccine supply is inevitable. We propose a spatial and dynamic vaccine allocation solution to assist in the allocation of limited vaccines to people who need them most. Methods We developed a weighted kernel density estimation (WKDE) model to predict daily COVID-19 symptom onset risk in 291 Tertiary Planning Units in Hong Kong from 18 January 2020 to 22 December 2020. Data of 5,409 COVID-19 onset cases were used. We then obtained spatial distributions of accumulated onset risk under three epidemic scenarios, and computed the vaccine demands to form the vaccine allocation plan. We also compared the vaccine demand under different real-time effective reproductive number (Rt) levels. Results The estimated vaccine usages in three epidemiologic scenarios are 30.86% - 45.78% of the Hong Kong population, which is within the total vaccine availability limit. In the sporadic cases or clusters of onset cases scenario, when 6.26% of the total population with travel history to high-risk areas can be vaccinated, the COVID-19 transmission between higher- and lower-risk areas can be reduced. Furthermore, if the current Rt is increased to double, the vaccine usages needed will be increased by more than 7%. Conclusions The proposed solution can be used to dynamically allocate limited vaccines in different epidemic scenarios, thereby enabling more effective protection. The increased vaccine usages associated with increased Rt indicates the necessity to maintain appropriate control measures even with vaccines available.

scholarly journals The effects of border control and quarantine measures on global spread of COVID-19

2020 ◽  
Author(s):  
M. Pear Hossain ◽  
Alvin Junus ◽  
Xiaolin Zhu ◽  
Pengfei Jia ◽  
Tzai-Hung Wen ◽  
...  
Keyword(s):  
Arrival Time ◽  
Control Measure ◽  
Control Measures ◽  
Rapid Expansion ◽  
Reproductive Number ◽  
Mathematical Framework ◽  
Border Control ◽  
Travel History ◽  
Global Spread ◽  
Imported Cases

AbstractThe rapid expansion of coronavirus (COVID-19) has been observed in many parts of the world. Many newly reported cases of this new coronavirus during early outbreak phases have been associated with travel history from an epidemic region (identified as imported cases). For those cases without travel history, the risk of wider spreads through community contact is even higher. However, most population models assume a homogeneous infected population without considering that the imported and secondary cases contracted by the imported cases can pose a different risk to community spread.We have developed an “easy-to-use” mathematical framework extending from a meta-population model embedding city-to-city connections to stratify the dynamics of transmission waves caused by imported, secondary, and others from an outbreak source region when control measures are considered. Using the dynamics of the secondary cases, we are able to determine the probability of community spread.Using the top 10 visiting cities from Wuhan in China as an example, we first demonstrated that the arrival time and the dynamics of the outbreaks at these cities can be successfully predicted under the reproductive number R0 = 2.92 and latent period τ = 5.2 days. Next, we showed that although control measures can gain extra 32.5 and 44.0 days in arrival time through a high intensive border control measure and a shorter time to quarantine under a low R0 (1.4), if the R0 is higher (2.92), only 10 extra days can be gained for each of the same measures. This suggests the importance of lowering the incidence at source regions together with infectious disease control measures in susceptible regions. The study allows us to assess the effects of border control and quarantine measures on the emergence and the global spread in a fully connected world using the dynamics of the secondary cases.

scholarly journals Effectiveness of quarantine measure on transmission dynamics of COVID-19 in Hong Kong

2020 ◽  
Author(s):  
Hsiang-Yu Yuan ◽  
Axiu Mao ◽  
Guiyuan Han ◽  
Hsiangkuo Yuan ◽  
Dirk Pfeiffer
Keyword(s):  
Hong Kong ◽  
Symptom Onset ◽  
Mainland China ◽  
Economic Loss ◽  
Control Measures ◽  
Rapid Expansion ◽  
Transmission Dynamics ◽  
Reproductive Number ◽  
Suspected Case ◽  
Infected Case

AbstractThe rapid expansion of COVID-19 has caused a global pandemic. Although quarantine measures have been used widely, the critical steps among them to suppress the outbreak without a huge social-economic loss remain unknown. Hong Kong, unlike other regions in the world, had a massive number of travellers from Mainland China during the early expansion period, and yet the spread of virus has been relatively limited. Understanding the effect of control measures to reduce the transmission in Hong Kong can improve the control of the virus spreading.We have developed a susceptible-exposed-infectious-quarantined-recovered (SEIQR) meta-population model that can stratify the infections into imported and subsequent local infections, and therefore to obtain the control effects on transmissibility in a region with many imported cases. We fitted the model to both imported and local confirmed cases with symptom onset from 18 January to 29 February 2020 in Hong Kong with daily transportation data and the transmission dynamics from Wuhan and Mainland China.The model estimated that the reproductive number was dropped from 2.32 to 0.76 (95% CI, 0.66 to 0.86) after an infected case was estimated to be quarantined half day before the symptom onset, corresponding to the incubation time of 5.43 days (95% CI, 1.30-9.47). If the quarantine happened about one day after the onset, community spread would be likely to occur, indicated by the reproductive number larger than one. The results suggest that the early quarantine for a suspected case before the symptom onset is a key factor to suppress COVID-19.

Water Quality in the Priority Watercourses of Hong Kong in Respect of Various Environmental Control Measures

1991 ◽  
Vol 23 (1-3) ◽  
pp. 85-91 ◽  
Author(s):  
Ho Kin-chung
Keyword(s):  
Water Quality ◽  
Hong Kong ◽  
Environmental Control ◽  
Control Measures ◽  
Livestock Waste ◽  
Water Control ◽  
Control Zone ◽  
Town Development ◽  
Control Scheme ◽  
Term Monitoring

The water quality in the 12 priority watercourses of Hong Kong was appraised in respect of the various environmental control measures being undertaken. It was noted that water quality in Lam Tsuen River had been significantly improved since 1983. This is attributed to recent resumption of unsewered lands for town development, training of river basin to increase flow, and declaration of the catchment as a “Water Control Zone” under the Water Pollution Control Ordinance. In contrast with the other heavily polluted watercourses to which little abatement measures were implemented, the water qualities of Shing Mun River and Tuen Mun River were slightly upgraded because of the efforts to rectify unauthorized industrial discharges back to foul sewer and provision of interceptors and sewers to villages. The 10 year Livestock Waste Control Scheme enforced on 24 June 1989 was found in parallel with BOD and suspended solids decrease in watercourses. To assess its effectiveness, however, a longer term monitoring is required to get a conclusive result.

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.

Ongoing transmission of avian influenza A viruses in Hong Kong despite very comprehensive poultry control measures: A prospective seroepidemiology study

2016 ◽  
Vol 72 (2) ◽  
pp. 207-213 ◽  
Author(s):  
Kelvin K.W. To ◽  
Ivan F.N. Hung ◽  
Yin-Ming Lui ◽  
Florence K.Y. Mok ◽  
Andy S.F. Chan ◽  
...  
Keyword(s):  
Hong Kong ◽  
Avian Influenza ◽  
Influenza A ◽  
Control Measures ◽  
Influenza A Viruses

Hong Kong’s response to COVID-19: a glance to the control measures and their enforcement

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ka Ki Lawrence Ho ◽  
Ying-Tung Chan
Keyword(s):  
Hong Kong ◽  
Infection Rate ◽  
Government Policy ◽  
Design Methodology ◽  
Control Measures ◽  
Content Type ◽  
The Government ◽  
And Control ◽  
Viral Outbreak

Purpose This study aims to examine Hong Kong’s responses to COVID-19, arguing that Hong Kong’s relatively low infection rate is due to self-discipline of citizens together with the enforcement measures introduced by the government. Design/methodology/approach This study reviewed the government policy announcements and the prevailing scholarly analyses on Hong Kong society during COVID-19. Findings It starts by examining the partial lockdown and control measures since mid-January, and the roles of different government units in enforcement were examined and assessed. Suppression of viral outbreak in Hong Kong should primarily be attributed to the appropriate lockdown and quarantine actions of the government. Originality/value However, outperformance of the frontline professionals and the highly aware, self-disciplined and mutually aided citizens in the community are also the key to the “interim success” by June 2020 in the highly accessible and densely populated city.

scholarly journals Analysis of a mosquito life cycle model

2021 ◽  
Vol Volume 34 - 2020 - Special... ◽  
Author(s):  
Albert Kouchéré ◽  
Hamadjam Abboubakar ◽  
Irepran Damakoa
Keyword(s):  
Life Cycle ◽  
Sterile Insect Technique ◽  
Deterministic Model ◽  
Communicable Disease ◽  
Control Measures ◽  
Reproductive Number ◽  
Gonotrophic Cycle ◽  
Complete Life Cycle ◽  
Trivial Equilibrium ◽  
International Audience

International audience The gonotrophic cycle of mosquitoes conditions the frequency of mosquito-human contacts. The knowledge of this important phenomenon in the mosquito life cycle is a fundamental element in the epidemiological analysis of a communicable disease such as mosquito-borne diseases.In this work, we analyze a deterministic model of the complete life cycle of mosquitoes which takes into account the principal phases of female mosquitoes' gonotrophic cycle, and the Sterile Insect technique combined with the use of insecticide as control measures to fight the proliferation of mosquitoes. We compute the corresponding mosquito reproductive number N ∗ and prove the global asymptotic stability of trivial equilibrium. We prove that the model admits two non-trivial equilibria whenever N^{∗} is greater than another threshold, N_c, which the total number of sterile mosquitoes depends on. Numerical simulations, using mosquito parameters of the Aedes species, are carried out to illustrate our analytical results and permit to show that the strategy which consists in combining the sterile insect technique with adulticides, when it is well done, effectively combats the proliferation of mosquitoes.

scholarly journals Effective COVID-19 Control: A Comparative Analysis of the Stringency and Timeliness of Government Responses in Asia

2021 ◽  
Vol 18 (16) ◽  
pp. 8686
Author(s):  
Shu Chen ◽  
Lei Guo ◽  
Taghred Alghaith ◽  
Di Dong ◽  
Mohammed Alluhidan ◽  
...  
Keyword(s):  
Public Health ◽  
Hong Kong ◽  
South Korea ◽  
Health System ◽  
Mainland China ◽  
Initial Response ◽  
Control Measures ◽  
System Control ◽  
East And Southeast Asia ◽  
Study Sites

Aim: Many governments in East and Southeast Asia responded promptly and effectively at the onset of the COVID-19 pandemic. Synthesizing and analyzing these responses is vital for disease control evidence-based policymaking. Methods: An extensive review of COVID-19 control measures was conducted in selected Asian countries and subregions, including Mainland China, Hong Kong, Taiwan, South Korea, Singapore, Japan, and Vietnam from 1 January to 30 May 2020. Control measures were categorized into administrative, public health, and health system measures. To evaluate the stringency and timeliness of responses, we developed two indices: the Initial Response Index (IRI) and the Modified Stringency Index (MSI), which builds on the Oxford COVID-19 Government Response Tracker (OxCGRT). Results: Comprehensive administrative, public health, and health system control measures were implemented at the onset of the outbreak. Despite variations in package components, the stringency of control measures across the study sites increased with the acceleration of the outbreak, with public health control measures implemented the most stringently. Variations in daily average MSI scores are observed, with Mainland China scoring the highest (74.2), followed by Singapore (67.4), Vietnam (66.8), Hong Kong (66.2), South Korea (62.3), Taiwan (52.1), and Japan (50.3). Variations in IRI scores depicting timeliness were higher: Hong Kong, Taiwan, Vietnam, and Singapore acted faster (IRI > 50.0), while Japan (42.4) and Mainland China (4.2) followed. Conclusions: Timely setting of stringency of the control measures, especially public health measures, at dynamically high levels is key to optimally controlling outbreaks.

scholarly journals Estimating the burden of SARS-CoV-2 in France

Science ◽  
2020 ◽  
Vol 369 (6500) ◽  
pp. 208-211 ◽  
Author(s):  
Henrik Salje ◽  
Cécile Tran Kiem ◽  
Noémie Lefrancq ◽  
Noémie Courtejoie ◽  
Paolo Bosetti ◽  
...  
Keyword(s):  
Intensive Care ◽  
Severe Acute Respiratory Syndrome ◽  
Credible Interval ◽  
Control Measures ◽  
Reproductive Number ◽  
Infected Population ◽  
Population Immunity ◽  
The Impact ◽  
Second Wave ◽  
Death Data

France has been heavily affected by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and went into lockdown on 17 March 2020. Using models applied to hospital and death data, we estimate the impact of the lockdown and current population immunity. We find that 2.9% of infected individuals are hospitalized and 0.5% of those infected die (95% credible interval: 0.3 to 0.9%), ranging from 0.001% in those under 20 years of age to 8.3% in those 80 years of age or older. Across all ages, men are more likely to be hospitalized, enter intensive care, and die than women. The lockdown reduced the reproductive number from 2.90 to 0.67 (77% reduction). By 11 May 2020, when interventions are scheduled to be eased, we project that 3.5 million people (range: 2.1 million to 6.0 million), or 5.3% of the population (range: 3.3 to 9.3%), will have been infected. Population immunity appears to be insufficient to avoid a second wave if all control measures are released at the end of the lockdown.

Sign in / Sign up

Export Citation Format

Share Document