scholarly journals Vaccination strategies to control Ebola epidemics in the context of variable household inaccessibility levels

2019 ◽  
Author(s):  
G. Chowell ◽  
A. Tariq ◽  
M. Kiskowski
Keyword(s):  
Vaccination Strategy ◽  
Qualitative Change ◽  
Health Interventions ◽  
Transmission Model ◽  
Individual Level ◽  
Vaccination Strategies ◽  
Ring Vaccination ◽  
Low Levels ◽  
The Impact ◽  
Close Contacts

AbstractDespite a very effective vaccine, active conflict and community distrust during the ongoing DRC Ebola epidemic are undermining control efforts, including a ring vaccination strategy that requires the prompt immunization of close contacts of infected individuals. However, in April 2019, it was reported 20% or more of close contacts cannot be reached or refuse vaccination [1], and it is predicted that the ring vaccination strategy would not be effective with such a high level of inaccessibility [2]. The vaccination strategy is now incorporating a “third ring” community-level vaccination that targets members of communities even if they are not known contacts of Ebola cases. To assess the impact of vaccination strategies for controlling Ebola epidemics in the context of variable levels of community accessibility, we employed an individual-level stochastic transmission model that incorporates four sources of heterogeneity: a proportion of the population is inaccessible for contact tracing and vaccination due to lack of confidence in interventions or geographic inaccessibility, two levels of population mixing resembling household and community transmission, two types of vaccine doses with different time periods until immunity, and transmission rates that depend on spatial distance. Our results indicate that a ring vaccination strategy alone would not be effective for containing the epidemic in the context of significant delays to vaccinating contacts even for low levels of household inaccessibility and affirm the positive impact of a supplemental community vaccination strategy. Our key results are that as levels of inaccessibility increase, there is a qualitative change in the effectiveness of the vaccination strategy. For higher levels of vaccine access, the probability that the epidemic will end steadily increases over time, even if probabilities are lower than they would be otherwise with full community participation. For levels of vaccine access that are too low, however, the vaccination strategies are not expected to be successful in ending the epidemic even though they help lower incidence levels, which saves lives, and makes the epidemic easier to contain and reduces spread to other communities. This qualitative change occurs for both types of vaccination strategies: ring vaccination is effective for containing an outbreak until the levels of inaccessibility exceeds approximately 10% in the context of significant delays to vaccinating contacts, a combined ring and community vaccination strategy is effective until the levels of inaccessibility exceeds approximately 50%. More broadly, our results underscore the need to enhance community engagement to public health interventions in order to enhance the effectiveness of control interventions to ensure outbreak containment.Author summaryIn the context of the ongoing Ebola epidemic in DRC, active conflict and community distrust are undermining control efforts, including vaccination strategies. In this paper, we employed an individual-level stochastic structured transmission model to assess the impact of vaccination strategies on epidemic control in the context of variable levels of household inaccessibility. We found that a ring vaccination strategy of close contacts would not be effective for containing the epidemic in the context of significant delays to vaccinating contacts even for low levels of household inaccessibility and evaluate the impact of a supplemental community vaccination strategy. For lower levels of inaccessibility, the probability of epidemic containment increases over time. For higher levels of inaccessibility, even the combined ring and community vaccination strategies are not expected to contain the epidemic even though they help lower incidence levels, which saves lives, makes the epidemic easier to contain and reduces spread to other communities. We found that ring vaccination is effective for containing an outbreak until the levels of inaccessibility exceeds approximately 10%, a combined ring and community vaccination strategy is effective until the levels of inaccessibility exceeds approximately 50%. Our findings underscore the need to enhance community engagement to public health interventions.

scholarly journals Clinical and economic impact of universal varicella vaccination in Norway: A modeling study

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254080
Author(s):  
Manjiri Pawaskar ◽  
Colleen Burgess ◽  
Mathew Pillsbury ◽  
Torbjørn Wisløff ◽  
Elmira Flem
Keyword(s):  
Cost Saving ◽  
Varicella Vaccine ◽  
Vaccination Strategy ◽  
Quadrivalent Vaccine ◽  
Transmission Model ◽  
Varicella Vaccination ◽  
Vaccination Strategies ◽  
Dynamic Transmission Model ◽  
Life Years ◽  
The Impact

Background Norway has not implemented universal varicella vaccination, despite the considerable clinical and economic burden of varicella disease. Methods An existing dynamic transmission model of varicella infection was calibrated to age-specific seroprevalence rates in Norway. Six two-dose vaccination strategies were considered, consisting of combinations of two formulations each of a monovalent varicella vaccine (Varivax® or Varilrix®) and a quadrivalent vaccine against measles-mumps-rubella-varicella (ProQuad® or PriorixTetra®), with the first dose given with a monovalent vaccine at age 15 months, and the second dose with either a monovalent or quadrivalent vaccine at either 18 months, 7 or 11 years. Costs were considered from the perspectives of both the health care system and society. Quality-adjusted life-years saved and incremental cost-effectiveness ratios relative to no vaccination were calculated. A one-way sensitivity analysis was conducted to assess the impact of vaccine efficacy, price, the costs of a lost workday and of inpatient and outpatient care, vaccination coverage, and discount rate. Results In the absence of varicella vaccination, the annual incidence of natural varicella is estimated to be 1,359 per 100,000 population, and the cumulative numbers of varicella outpatient cases, hospitalizations, and deaths over 50 years are projected to be 1.81 million, 10,161, and 61, respectively. Universal varicella vaccination is projected to reduce the natural varicella incidence rate to 48–59 per 100,000 population, depending on the vaccination strategy, and to reduce varicella outpatient cases, hospitalizations, and deaths by 75–85%, 67–79%, and 75–79%, respectively. All strategies were cost-saving, with the most cost-saving as two doses of Varivax® at 15 months and 7 years (payer perspective) and two doses of Varivax® at 15 months and 18 months (societal perspective). Conclusions All modeled two-dose varicella vaccination strategies are projected to lead to substantial reductions in varicella disease and to be cost saving compared to no vaccination in Norway.

scholarly journals Evolution of disease transmission during the COVID-19 pandemic: patterns and determinants

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jie Zhu ◽  
Blanca Gallego
Keyword(s):  
Public Health ◽  
Disease Transmission ◽  
Clustering Algorithm ◽  
Health Interventions ◽  
Transmission Model ◽  
Model Parameters ◽  
Public Health Interventions ◽  
Forecasting Accuracy ◽  
Time Lagged ◽  
The Impact

AbstractEpidemic models are being used by governments to inform public health strategies to reduce the spread of SARS-CoV-2. They simulate potential scenarios by manipulating model parameters that control processes of disease transmission and recovery. However, the validity of these parameters is challenged by the uncertainty of the impact of public health interventions on disease transmission, and the forecasting accuracy of these models is rarely investigated during an outbreak. We fitted a stochastic transmission model on reported cases, recoveries and deaths associated with SARS-CoV-2 infection across 101 countries. The dynamics of disease transmission was represented in terms of the daily effective reproduction number ($$R_t$$ R t ). The relationship between public health interventions and $$R_t$$ R t was explored, firstly using a hierarchical clustering algorithm on initial $$R_t$$ R t patterns, and secondly computing the time-lagged cross correlation among the daily number of policies implemented, $$R_t$$ R t , and daily incidence counts in subsequent months. The impact of updating $$R_t$$ R t every time a prediction is made on the forecasting accuracy of the model was investigated. We identified 5 groups of countries with distinct transmission patterns during the first 6 months of the pandemic. Early adoption of social distancing measures and a shorter gap between interventions were associated with a reduction on the duration of outbreaks. The lagged correlation analysis revealed that increased policy volume was associated with lower future $$R_t$$ R t (75 days lag), while a lower $$R_t$$ R t was associated with lower future policy volume (102 days lag). Lastly, the outbreak prediction accuracy of the model using dynamically updated $$R_t$$ R t produced an average AUROC of 0.72 (0.708, 0.723) compared to 0.56 (0.555, 0.568) when $$R_t$$ R t was kept constant. Monitoring the evolution of $$R_t$$ R t during an epidemic is an important complementary piece of information to reported daily counts, recoveries and deaths, since it provides an early signal of the efficacy of containment measures. Using updated $$R_t$$ R t values produces significantly better predictions of future outbreaks. Our results found variation in the effect of early public health interventions on the evolution of $$R_t$$ R t over time and across countries, which could not be explained solely by the timing and number of the adopted interventions.

scholarly journals Evolution of disease transmission rate during the course of SARS-COV-2: Patterns and determinants

2020 ◽  
Author(s):  
Jie Zhu ◽  
Blanca Gallego
Keyword(s):  
Public Health ◽  
Disease Transmission ◽  
Reproduction Number ◽  
Transmission Rate ◽  
Region Of Interest ◽  
Health Interventions ◽  
Transmission Model ◽  
Public Health Interventions ◽  
Containment Measures ◽  
The Impact

Abstract To date, many studies have argued the potential impact of public health interventions on flattening the epidemic curve of SARS-CoV-2. Most of them have focused on simulating the impact of interventions in a region of interest by manipulating contact patterns and key transmission parameters to reflect different scenarios. Our study looks into the evolution of the daily effective reproduction number during the epidemic via a stochastic transmission model. We found this measure (although model-dependent) provides an early signal of the efficacy of containment measures. This epidemiological parameter when updated in real-time can also provide better predictions of future outbreaks. Our results found a substantial variation in the effect of public health interventions on the dynamic of SARS-CoV-2 transmission over time and across countries, that could not be explained solely by the timing and number of the adopted interventions. This suggests that further knowledge about the idiosyncrasy of their implementation and effectiveness is required. Although sustained containment measures have successfully lowered growth in disease transmission, more than half of the 101 studied countries failed to maintain the effective reproduction number close to or below 1. This resulted in continued growth in reported cases. Finally, we were able to predict with reasonable accuracy which countries would experience outbreaks in the next 30 days.

scholarly journals Preventing the Risk of Hospitalization for Respiratory Complications of Influenza among the Elderly: Is There a Better Influenza Vaccination Strategy? A Retrospective Population Study

Vaccines ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 344
Author(s):  
Silvia Cocchio ◽  
Tolinda Gallo ◽  
Stefania Del Zotto ◽  
Elena Clagnan ◽  
Andrea Iob ◽  
...  
Keyword(s):  
Influenza Vaccination ◽  
Vaccination Strategy ◽  
The Elderly ◽  
Protective Role ◽  
The Body ◽  
Health Concern ◽  
Respiratory Complications ◽  
Effective Prevention ◽  
Vaccination Strategies ◽  
The Impact

Influenza and its complications are an important public health concern, and vaccination remains the most effective prevention measure. However, the efficacy of vaccination depends on several variables, including the type of strategy adopted. The goal of this study was to assess the impact of different influenza vaccination strategies in preventing hospitalizations for influenza and its related respiratory complications. A retrospective cohort study was conducted on data routinely collected by the health services for six consecutive influenza seasons, considering the population aged 65 years or more at the time of their vaccination and living in northeastern Italy. Our analysis concerns 987,266 individuals vaccinated against influenza during the study period. The sample was a mean 78.0 ± 7.7 years old, and 5681 individuals (0.58%) were hospitalized for potentially influenza-related reasons. The hospitalization rate tended to increase over the years, not-significantly peaking in the 2016–2017 flu season (0.8%). Our main findings revealed that hospitalizations related to seasonal respiratory diseases were reduced as the use of the enhanced vaccine increased (R2 = 0.5234; p < 0.001). Multivariate analysis confirmed the significantly greater protective role of the enhanced vaccine over the conventional vaccination strategy, with adjusted Odds Ratio (adj OR) = 0.62 (95% CI: 0.59–0.66). A prior flu vaccination also had a protective role (adj OR: 0.752 (95% CI: 0.70–0.81)). Age, male sex, and H3N2 mismatch were directly associated with a higher risk of hospitalization for pneumonia. In the second part of our analysis, comparing MF59-adjuvanted trivalent inactivated vaccine (MF59-TIV) with conventional vaccines, we considered 479,397 individuals, of which 3176 (0.66%) were admitted to a hospital. The results show that using the former vaccine reduced the risk of hospitalization by 33% (adj OR: 0.67 (95% CI: 0.59–0.75)). This study contributes to the body of evidence of a greater efficacy of enhanced vaccines, and MF59-adjuvanted TIV in particular, over conventional vaccination strategies in the elderly.

Modelling the impact of one-dose vs. two-dose vaccination regimens on the epidemiology of varicella zoster virus in Australia

2009 ◽  
Vol 138 (4) ◽  
pp. 457-468 ◽  
Author(s):  
Z. GAO ◽  
H. F. GIDDING ◽  
J. G. WOOD ◽  
C. R. MacINTYRE
Keyword(s):  
Mathematical Model ◽  
Varicella Zoster Virus ◽  
Vaccination Strategy ◽  
Vaccination Schedule ◽  
Varicella Zoster ◽  
Dose Strategy ◽  
Vaccination Strategies ◽  
Age Of Infection ◽  
The Impact

SUMMARYWe examined the impact of one-dose vs. two-dose vaccination strategies on the epidemiology of varicella zoster virus (VZV) in Australia, using a mathematical model. Strategies were assessed in terms of varicella (natural and breakthrough) and zoster incidence, morbidity, average age of infection and vaccine effectiveness (VE). Our modelling results suggest that compared to a one-dose vaccination strategy (Australia's current vaccination schedule), a two-dose strategy is expected to not only produce less natural varicella cases (5% vs. 13% of pre-vaccination state, respectively) but also considerably fewer breakthrough varicella cases (only 11·4% of one-dose strategy). Therefore a two-dose infant vaccination programme would be a better long-term strategy for Australia.

scholarly journals The Artist as Innovation Muse: Findings from a Residence Program in the Fuzzy Front End

2020 ◽  
Vol 10 (4) ◽  
pp. 88
Author(s):  
Berit Sandberg
Keyword(s):  
Qualitative Content Analysis ◽  
Idea Generation ◽  
Business Environment ◽  
Transmission Model ◽  
Individual Level ◽  
Fuzzy Front End ◽  
Work Related ◽  
Front End ◽  
Scientists And Engineers ◽  
The Impact

In a highly competitive business environment, integrating artists into corporate research and development (R&D) seems to be a promising way to foster inventiveness and idea generation. Given the importance of individual level innovation for product development, this study explores the benefits that employees experience from the artist-in-residence-program at Robert Bosch GmbH, Germany. Qualitative content analysis of interviews with scientists and engineers was performed in order to explore the impact of their encounters with artists in the theoretical framework of the triadic concept and transmission model of inspiration. The findings corroborate the notion that inspiration is a suitable theoretical underpinning for individual benefits of art–science collaborations in the front end of innovation. Scientists and engineers are inspired by the artists’ otherness and transcend their usual modes of perception in favor of enhanced focal, peripheral and bifocal vision. Whereas shifts in perspective are reflected in individual thinking patterns, researchers are hardly motivated to change their work-related behavior. The exchange with artists does not have a concrete impact on technological innovation, because researchers neither integrate impulses into their experiential world nor link them to fields of activity. In the case under scrutiny, artistic impulses do not contribute to idea generation in the sense of front-end activities. The study contributes to research on artists in businesses by illuminating the R&D environment as a hitherto neglected field of activity. While substantiating previous research on artist-in-science-residencies, the results suggest that the potential of such interdisciplinary endeavors is limited.

scholarly journals The role of connectivity on COVID-19 preventive approaches

2021 ◽  
Author(s):  
V. Miró Pina ◽  
J. Nava-Trejo ◽  
A. Tóbiás ◽  
E. Nzabarushimana ◽  
A. Gonzalez-Casanova ◽  
...  
Keyword(s):  
Public Health ◽  
Contact Structure ◽  
Vaccination Strategy ◽  
Demographic Characteristics ◽  
Health Interventions ◽  
Public Health Interventions ◽  
The Impact ◽  
Modelling Approaches

AbstractPreventive and modelling approaches to address the COVID-19 pandemic have been primarily based on the age or occupation, and often disregard the importance of the population contact structure and individual connectivity. To address this gap, we developed models that first incorporate the role of heterogeneity and connectivity and then can be expanded to make assumptions about demographic characteristics. Results demonstrate that variations in the number of connections of individuals within a population modify the impact of public health interventions such vaccination approaches. We conclude that the most effective vaccination strategy will vary depending on the underlying contact structure of individuals within a population and on timing of the interventions.

scholarly journals Assessing vaccination priorities for different ages and age-specific vaccination strategies of COVID-19 using an SEIR modelling approach

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261236
Author(s):  
Cong Yang ◽  
Yali Yang ◽  
Yang Li
Keyword(s):  
Young People ◽  
Reproduction Number ◽  
Vaccination Strategy ◽  
The Elderly ◽  
Seir Model ◽  
Global Epidemic ◽  
Vaccination Strategies ◽  
The Past ◽  
The Impact ◽  
Modelling Approach

In the past year, the global epidemic situation is still not optimistic, showing a trend of continuous expansion. With the research and application of vaccines, there is an urgent need to develop some optimal vaccination strategies. How to make a reasonable vaccination strategy to determine the priority of vaccination under the limited vaccine resources to control the epidemic and reduce human casualties? We build a dynamic model with vaccination which is extended the classical SEIR model. By fitting the epidemic data of three countries—China, Brazil, Indonesia, we have evaluated age-specific vaccination strategy for the number of infections and deaths. Furthermore, we have evaluated the impact of age-specific vaccination strategies on the number of the basic reproduction number. At last, we also have evaluated the different age structure of the vaccination priority. It shows that giving priority to vaccination of young people can control the number of infections, while giving priority to vaccination of the elderly can greatly reduce the number of deaths in most cases. Furthermore, we have found that young people should be mainly vaccinated to reduce the number of infections. When the emphasis is on reducing the number of deaths, it is important to focus vaccination on the elderly. Simulations suggest that appropriate age-specific vaccination strategies can effectively control the epidemic, both in terms of the number of infections and deaths.

Legislative Territorialization: The Impact of a Decentralized Party System on Individual Legislative Behavior in Argentina

2020 ◽  
Vol 51 (1) ◽  
pp. 104-130
Author(s):  
Paula Clerici
Keyword(s):  
Party System ◽  
Legislative Behavior ◽  
Roll Call ◽  
Individual Level ◽  
Ideal Points ◽  
Low Levels ◽  
The Government ◽  
Main Dimension ◽  
The Individual ◽  
The Impact

Abstract The conventional understanding in the scholarly literature is that the main dimension that sets legislators’ ideal points is the tension between the government and the opposition parties. In this article, I challenge this claim, demonstrating that this alignment is contingent on the level of party system nationalization. These consequences have not been fully documented. Using DW-NOMINATE to calculate Argentine legislators’ ideal points (1983–2017), I show that individual territorialization in roll call voting increases when the party system is more decentralized. Legislators are closer to their provincial delegation, irrespective of which party they belong to, when there are low levels of party nationalization. At the individual level, this mechanism may be understood by the competing principals’ theory: because party system decentralization implies a response to local dynamics over national dynamics, cross-pressured legislators may favor their subnational principal.

scholarly journals An SVEICRD model for assessing the impact of the lock-down intervention and vaccination strategies on the spread of COVID-19

2021 ◽  
Author(s):  
Idil Aydin ◽  
Aysun Bozanta ◽  
Mucahit Cevik ◽  
Ayse Basar
Keyword(s):  
Numerical Study ◽  
Vaccination Strategy ◽  
Alternative Strategies ◽  
Vaccination Strategies ◽  
The Uk ◽  
Fourth Wave ◽  
The Impact ◽  
Death Cases

In this research, we aim to forecast the trajectory of the COVID-19 pandemic in terms of the number of exposed, infected, vaccinated, hospitalized, recovered, and dead people, and observe the effects of different vaccination strategies on the spread of the COVID-19. We simulate the ongoing trajectory of the outbreak in three countries, namely, Canada, the UK, and Israel using the susceptible - vaccinated - exposed - infected - critical - recovered - dead (SVEICRD) model. We consider two vaccination strategies and investigate their effects on the number of exposed and death cases. We perform an extensive numerical study to assess the implications of different strategies and spread scenarios. Our findings confirm that the fourth wave has begun in all three countries, and already reached its peak. We observe that starting second dose vaccination as early as possible is the most effective in mitigating the spread of COVID-19, although it does require more vaccination supply than the alternative strategies. Our results show that the SVEICRD model successfully forecasts the changing number of people in each compartment and the vaccination strategy significantly impacts the trajectory of the outbreak.

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