Early intervention is the key to success in COVID-19 control

AbstractNew Zealand responded to the COVID-19 pandemic with a combination of border restrictions and an Alert Level system that included strict stay-at-home orders. These interventions were successful in containing the outbreak and ultimately eliminating community transmission of COVID-19. The timing of interventions is crucial to their success. Delaying interventions for too long may both reduce their effectiveness and mean that they need to be maintained for a longer period of time. Here, we use a stochastic branching process model of COVID-19 transmission and control to simulate the epidemic trajectory in New Zealand and the effect of its interventions during its COVID-19 outbreak in March-April 2020. We use the model to calculate key outcomes, including the peak load on the contact tracing system, the total number of reported COVID-19 cases and deaths, and the probability of elimination within a specified time frame. We investigate the sensitivity of these outcomes to variations in the timing of the interventions. We find that a delay to the introduction of Alert Level 4 controls results in considerably worse outcomes. Changes in the timing of border measures have a smaller effect. We conclude that the rapid response in introducing stay-at-home orders was crucial in reducing the number of cases and deaths and increasing the probability of elimination.Executive SummaryEvaluating the effectiveness of New Zealand’s COVID-19 response, relative to hypothetical response scenarios, is important for guiding future response strategies. We assess the importance of early implementation of interventions for controlling COVID-19.We model counterfactual (alternative ‘what-if’) scenarios in which the timings of three policy interventions are varied: border restrictions requiring 14-day quarantine of all international arrivals, border closure except to returning residents and citizens, and Alert Level 4 restrictions.Key measures describing the dynamics of a COVID-19 outbreak (notably peak load on the contact tracing system, the total number of reported COVID-19 cases and deaths, and the probability of elimination within a specified time frame), are used to compare outcomes from each scenario with New Zealand’s actual outcomes.Key measures were more sensitive to the timing of Alert Level 4, than to timing of border restrictions and border closure. Of the three counterfactual scenarios, an earlier start to Alert Level 4 would have resulted in the greatest reduction in numbers of cases and deaths.Delaying the start of Alert Level 4 by 20 days could have led to over 11,500 cases and 200 deaths, and would have substantially reduced the probability of eliminating community transmission of COVID-19, requring a longer period at Alert Level 4 to achieve control.

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Simulating the impact of vaccination rates on the initial stages of a COVID-19 outbreak in New Zealand (Aotearoa) with a stochastic model

10.1101/2021.11.22.21266721 ◽

2021 ◽

Author(s):

Leighton M Watson

Keyword(s):

New Zealand ◽

Stochastic Model ◽

Process Model ◽

Branching Process ◽

Total Population ◽

Median Number ◽

Vaccination Rate ◽

Vaccination Rates ◽

The Impact ◽

Different Levels

Aim: The August 2021 COVID-19 outbreak in Auckland has caused the New Zealand government to transition from an elimination strategy to suppression, which relies heavily on high vaccination rates in the population. As restrictions are eased and as COVID-19 leaks through the Auckland boundary, there is a need to understand how different levels of vaccination will impact the initial stages of COVID-19 outbreaks that are seeded around the country. Method: A stochastic branching process model is used to simulate the initial spread of a COVID-19 outbreak for different vaccination rates. Results: High vaccination rates are effective at minimizing the number of infections and hospitalizations. Increasing vaccination rates from 20% (approximate value at the start of the August 2021 outbreak) to 80% (approximate proposed target) of the total population can reduce the median number of infections that occur within the first four weeks of an outbreak from 1011 to 14 (25th and 75th quantiles of 545-1602 and 2-32 for V=20% and V=80%, respectively). As the vaccination rate increases, the number of breakthrough infections (infections in fully vaccinated individuals) and hospitalizations of vaccinated individuals increases. Unvaccinated individuals, however, are 3.3x more likely to be infected with COVID-19 and 25x more likely to be hospitalized. Conclusion: This work demonstrates the importance of vaccination in protecting individuals from COVID-19, preventing high caseloads, and minimizing the number of hospitalizations and hence limiting the pressure on the healthcare system.

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This is Wellington: The Representation of Wellington in New Zealand Tourism Film from 1912 to 2017

10.26686/wgtn.17068265.v1 ◽

2021 ◽

Author(s):

◽

Diego Bonelli

Keyword(s):

New Zealand ◽

Turning Points ◽

Time Frame ◽

Film Production ◽

Tourism Marketing ◽

Secondary Sources ◽

Planning And Control ◽

Archival Documents ◽

The One ◽

And Control

<p>This thesis analyses the representation of Wellington in tourism films between 1912, the year in which the first New Zealand tourism film depicting Wellington was released, until 2017, the production year of the last case study. It also aims to trace both the dynamics of formal, stylistic and narrative development and the contexts of circulation of New Zealand tourism film. This thesis relies on the textual analysis of case studies conceived for different distribution platforms, selected according to their stylistic, formal, thematic and narrative relevance and to the availability of related archival documents; on the analysis of archival material related to New Zealand film production; on interviews with key informants involved in local tourism film production and tourism marketing; on the analysis of scholarly sources. This research argues that the depiction of Wellington has been regularly underpinned by a set of economic, social and political factors that changed throughout time and that determined shifts and turning points in its representation. More broadly, it observes how New Zealand tourism film was on the one hand characterised by a tendency towards formal, stylistic and narrative experimentation while on the other it was constantly subjected to forms of institutional planning and control. This thesis aims to contribute to film studies in different ways. First, it defines tourism film as a subject of study, identifying its characteristics and recognizing its importance and persistence in the context of New Zealand film production. Secondly, it proposes a research methodology for tourism film based on the combined examination of different types of primary and secondary sources that can be potentially applied in different geographic contexts. Finally, it sheds light on the shifts and turning points in the representation of Wellington and New Zealand urban and suburban space throughout over a century of national tourism promotion and tourism film production. In this research, the term ‘tourism film’ has been used in its broadest sense and it is meant to include the variety of technologies and media texts that emerged throughout the analysed 105 years time frame covered in this thesis.</p>

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A Branching Process Model for the Novel Coronavirus (Covid-19) Spread in Greece

International Journal of Modeling and Optimization ◽

10.7763/ijmo.2021.v11.779 ◽

2021 ◽

pp. 63-69

Author(s):

Ioanna A. Mitrofani ◽

◽

Vasilis P. Koutras

Keyword(s):

Process Model ◽

Branching Process ◽

Early Stage ◽

Branching Processes ◽

Relevant Literature ◽

Control Measures ◽

The Novel ◽

Simple Exponential Smoothing ◽

Novel Coronavirus ◽

And Control

The novel coronavirus (covid-19) was initially identified at the end of 2019 and caused a global health care crisis. The increased transmissibility of the virus, that led to high mortality, raises the interest of scientists worldwide. Thus, various methods and models have been extensively discussed, so to study and control covid-19 transmission. Mathematical modeling constitutes an important tool to estimate key parameters of the transmission and predict the dynamic of the virus. More precisely, in the relevant literature, epidemiology is considered as a classical application area of branching processes, which are stochastic individual-based processes. In this paper, we develop a classical Galton-Watson branching process approach for the covid-19 spread in Greece at the early stage. This approach is structured in two parts, initial and latter transmission stages, so to provide a comprehensive view of the virus spread through basic and effective reproduction numbers respectively, along with the probability of an outbreak. Additionally, the effectiveness of control measures is discussed, based on a simple exponential smoothing model, which is used to build a non-mitigation scenario. Finally, our primary aim is to model all transmission stages through branching processes in order to analyze the first semiannual spread of the ongoing coronavirus pandemic in the region of Greece.

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Interventions targeting nonsymptomatic cases can be important to prevent local outbreaks: COVID-19 as a case-study

10.1101/2020.11.06.20226969 ◽

2020 ◽

Author(s):

F.A. Lovell-Read ◽

S. Funk ◽

U. Obolski ◽

C.A. Donnelly ◽

R.N. Thompson

Keyword(s):

Infectious Disease ◽

Optimal Strategy ◽

Process Model ◽

Branching Process ◽

Host Population ◽

Imported Cases ◽

New Locations ◽

Disease Epidemics ◽

And Control

ABSTRACTBackgroundDuring infectious disease epidemics, a key question is whether cases travelling to new locations will trigger local outbreaks. The risk of this occurring depends on a range of factors, such as the transmissibility of the pathogen, the susceptibility of the host population and, crucially, the effectiveness of local surveillance in detecting cases and preventing onward spread. For many pathogens, presymptomatic and/or asymptomatic (together referred to here as nonsymptomatic) transmission can occur, making effective surveillance challenging. In this study, using COVID-19 as a case-study, we show how the risk of local outbreaks can be assessed when nonsymptomatic transmission can occur.MethodsWe construct a branching process model that includes nonsymptomatic transmission, and explore the effects of interventions targeting nonsymptomatic or symptomatic hosts when surveillance resources are limited. Specifically, we consider whether the greatest reductions in local outbreak risks are achieved by increasing surveillance and control targeting nonsymptomatic or symptomatic cases, or a combination of both.FindingsSeeking to increase surveillance of symptomatic hosts alone is typically not the optimal strategy for reducing outbreak risks. Adopting a strategy that combines an enhancement of surveillance of symptomatic cases with efforts to find and isolate nonsymptomatic hosts leads to the largest reduction in the probability that imported cases will initiate a local outbreak.InterpretationDuring epidemics of COVID-19 and other infectious diseases, effective surveillance for nonsymptomatic hosts can be crucial to prevent local outbreaks.

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This is Wellington: The Representation of Wellington in New Zealand Tourism Film from 1912 to 2017

10.26686/wgtn.17068265 ◽

2021 ◽

Author(s):

◽

Diego Bonelli

Keyword(s):

New Zealand ◽

Turning Points ◽

Time Frame ◽

Film Production ◽

Tourism Marketing ◽

Secondary Sources ◽

Planning And Control ◽

Archival Documents ◽

The One ◽

And Control

<p>This thesis analyses the representation of Wellington in tourism films between 1912, the year in which the first New Zealand tourism film depicting Wellington was released, until 2017, the production year of the last case study. It also aims to trace both the dynamics of formal, stylistic and narrative development and the contexts of circulation of New Zealand tourism film. This thesis relies on the textual analysis of case studies conceived for different distribution platforms, selected according to their stylistic, formal, thematic and narrative relevance and to the availability of related archival documents; on the analysis of archival material related to New Zealand film production; on interviews with key informants involved in local tourism film production and tourism marketing; on the analysis of scholarly sources. This research argues that the depiction of Wellington has been regularly underpinned by a set of economic, social and political factors that changed throughout time and that determined shifts and turning points in its representation. More broadly, it observes how New Zealand tourism film was on the one hand characterised by a tendency towards formal, stylistic and narrative experimentation while on the other it was constantly subjected to forms of institutional planning and control. This thesis aims to contribute to film studies in different ways. First, it defines tourism film as a subject of study, identifying its characteristics and recognizing its importance and persistence in the context of New Zealand film production. Secondly, it proposes a research methodology for tourism film based on the combined examination of different types of primary and secondary sources that can be potentially applied in different geographic contexts. Finally, it sheds light on the shifts and turning points in the representation of Wellington and New Zealand urban and suburban space throughout over a century of national tourism promotion and tourism film production. In this research, the term ‘tourism film’ has been used in its broadest sense and it is meant to include the variety of technologies and media texts that emerged throughout the analysed 105 years time frame covered in this thesis.</p>

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Likelihood of infecting or getting infected with COVID-19 as a function of vaccination status, as investigated with a stochastic model for New Zealand (Aotearoa)

10.1101/2021.11.28.21266967 ◽

2021 ◽

Author(s):

Leighton M Watson

Keyword(s):

New Zealand ◽

Process Model ◽

Branching Process ◽

Total Population ◽

Population Level ◽

Vaccination Rate ◽

Vaccination Status ◽

Government Action ◽

Vaccination Rates ◽

Eligible Population

Aim: The New Zealand government is transitioning from the Alert Level framework, which relies on government action and population level controls, to the COVID-19 Protection Framework, which relies on vaccination rates and allows for greater freedoms (for the vaccinated). As restrictions are eased, there is significant interest in understanding the relative risk of spreading COVID-19 posed by unvaccinated and vaccinated individuals. Methods: A stochastic branching process model is used to simulate the spread of COVID-19 for outbreaks seeded by unvaccinated or vaccinated individuals. The likelihood of infecting or getting infected with COVID-19 is calculated based on vaccination status. Results: A vaccinated traveler infected with COVID-19 is 9x less likely to seed an outbreak than an unvaccinated traveler infected with COVID-19. For a vaccination rate of 50%, unvaccinated individuals are responsible for 87% of all infections whereas 3% of infections are from vaccinated to vaccinated. When normalized by population, a vaccinated individual is 6.8x more likely to be infected by an unvaccinated individual than by a vaccinated individual. For a total population vaccination rate of 78.7%, which is equivalent to the 90% vaccination target for the eligible population (over 12 years old), this means that vaccinated individuals are 1.9x more likely to be infected by an unvaccinated individual than by a vaccinated, even though there are 3.7x more vaccinated individuals in the population. Conclusions: This work demonstrates that most new infections are caused by unvaccinated individuals. These simulations illustrate the importance of vaccination in stopping individuals from becoming infected with COVID-19 and in preventing onward transmission.

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Interventions targeting non-symptomatic cases can be important to prevent local outbreaks: SARS-CoV-2 as a case study

Journal of The Royal Society Interface ◽

10.1098/rsif.2020.1014 ◽

2021 ◽

Vol 18 (178) ◽

pp. 20201014

Author(s):

Francesca A. Lovell-Read ◽

Sebastian Funk ◽

Uri Obolski ◽

Christl A. Donnelly ◽

Robin N. Thompson

Keyword(s):

Infectious Disease ◽

Optimal Strategy ◽

Process Model ◽

Branching Process ◽

Host Population ◽

Imported Cases ◽

New Locations ◽

Disease Epidemics ◽

And Control

During infectious disease epidemics, an important question is whether cases travelling to new locations will trigger local outbreaks. The risk of this occurring depends on the transmissibility of the pathogen, the susceptibility of the host population and, crucially, the effectiveness of surveillance in detecting cases and preventing onward spread. For many pathogens, transmission from pre-symptomatic and/or asymptomatic (together referred to as non-symptomatic) infectious hosts can occur, making effective surveillance challenging. Here, by using SARS-CoV-2 as a case study, we show how the risk of local outbreaks can be assessed when non-symptomatic transmission can occur. We construct a branching process model that includes non-symptomatic transmission and explore the effects of interventions targeting non-symptomatic or symptomatic hosts when surveillance resources are limited. We consider whether the greatest reductions in local outbreak risks are achieved by increasing surveillance and control targeting non-symptomatic or symptomatic cases, or a combination of both. We find that seeking to increase surveillance of symptomatic hosts alone is typically not the optimal strategy for reducing outbreak risks. Adopting a strategy that combines an enhancement of surveillance of symptomatic cases with efforts to find and isolate non-symptomatic infected hosts leads to the largest reduction in the probability that imported cases will initiate a local outbreak.

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Modelling and control of an alkaline water electrolysis process

International Journal of Computational Physics Series ◽

10.29167/a1i2p9-14 ◽

2018 ◽

Vol 1 (2) ◽

pp. 9-14

Author(s):

Marisol Cervantes-Bobadilla ◽

Ricardo Fabricio Escobar Jiménez ◽

José Francisco Gómez Aguilar ◽

Tomas Emmanuel Higareda Pliego ◽

Alberto Armando Alvares Gallegos

Keyword(s):

Process Model ◽

Water Electrolysis ◽

Alkaline Water Electrolysis ◽

Alkaline Water ◽

Electrolysis Process ◽

Linear Dynamic ◽

Energy Current ◽

Identification Technique ◽

Nonlinear Static ◽

And Control

In this research, an alkaline water electrolysis process is modelled. The electrochemical electrolysis is carried out in an electrolyzer composed of 12 series-connected steel cells with a solution 30% wt of potassium hydroxide. The electrolysis process model was developed using a nonlinear identification technique based on the Hammerstein structure. This structure consists of a nonlinear static block and a linear dynamic block. In this work, the nonlinear static function is modelled by a polynomial approximation equation, and the linear dynamic is modelled using the ARX structure. To control the current feed to the electrolyzer an unconstraint predictive controller was implemented, once the unconstrained MPC was simulated, some restrictions are proposed to design a constrained MPC (CMPC). The CMPC aim is to reduce the electrolyzer's energy consumption (power supply current). Simulation results showed the advantages of using the CMPC since the energy (current) overshoots are avoided.

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Effective infection prevention and control strategies in a large accredited psychiatric facility in Singapore

10.31234/osf.io/89uc5 ◽

2020 ◽

Author(s):

Daniel Poremski ◽

Sandra Henrietta Subner ◽

Grace Lam Fong Kin ◽

Raveen Dev Ram Dev ◽

Mok Yee Ming ◽

...

Keyword(s):

Mental Health ◽

Prevention And Control ◽

Infection Prevention ◽

Control Strategies ◽

Infection Prevention And Control ◽

Psychiatric Facility ◽

Essential Services ◽

Community Transmission ◽

And Control

The Institute of Mental Health in Singapore continues to attempt to prevent the introduction of COVID-19, despite community transmission. Essential services are maintained and quarantine measures are currently unnecessary. To help similar organizations, strategies are listed along three themes: sustaining essential services, preventing infection, and managing human and consumable resources.

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