scholarly journals Targeted vaccination and the speed of SARS-CoV-2 adaptation

2021 ◽  
Author(s):  
Sylvain Gandon ◽  
Sébastien Lion
Keyword(s):  
Vaccination Strategy ◽  
Rate Of Change ◽  
Escape Mutant ◽  
Slowing Down ◽  
Vaccination Strategies ◽  
Viral Adaptation ◽  
Vaccine Escape Mutant ◽  
Speed Up ◽  
Pros And Cons ◽  
Evolutionary Consequences

The limited supply of vaccines against SARS-CoV-2 raises the question of targeted vaccination. Older and more sensitive hosts should be vaccinated first to minimize the disease burden. But what are the evolutionary consequences of targeted vaccination? We clarify the consequences of different vaccination strategies through the analysis of the speed of viral adaptation measured as the rate of change of the frequency of vaccine-escape mutations. We show that a vaccine-escape mutant is expected to spread faster if vaccination targets individuals which are likely to be involved in a higher number of contacts. We also discuss the pros and cons of dose-sparing strategies. Because delaying the second dose increases the proportion of the population vaccinated with a single dose, this strategy can both speed-up the spread of the vaccine-escape mutant and reduce the cumulated number of deaths. Hence, slowing down viral adaptation may not always be the optimal vaccination strategy. We contend that a careful assessment of the consequences of alternative vaccination strategies on both (i) the speed of adaptation and (ii) the mortality is required to determine which individuals should be vaccinated first.

scholarly journals Targeted vaccination and the speed of SARS-CoV-2 adaptation

2022 ◽  
Vol 119 (3) ◽  
pp. e2110666119
Author(s):  
Sylvain Gandon ◽  
Sébastien Lion
Keyword(s):  
Disease Burden ◽  
Rate Of Change ◽  
Cumulative Number ◽  
Vaccination Strategies ◽  
Viral Adaptation ◽  
Speed Up ◽  
Pros And Cons ◽  
Limited Supply ◽  
Evolutionary Consequences ◽  
Careful Assessment

The limited supply of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) raises the question of targeted vaccination. Many countries have opted to vaccinate older and more sensitive hosts first to minimize the disease burden. However, what are the evolutionary consequences of targeted vaccination? We clarify the consequences of different vaccination strategies through the analysis of the speed of viral adaptation measured as the rate of change of the frequency of a vaccine-adapted variant. We show that such a variant is expected to spread faster if vaccination targets individuals who are likely to be involved in a higher number of contacts. We also discuss the pros and cons of dose-sparing strategies. Because delaying the second dose increases the proportion of the population vaccinated with a single dose, this strategy can both speed up the spread of the vaccine-adapted variant and reduce the cumulative number of deaths. Hence, strategies that are most effective at slowing viral adaptation may not always be epidemiologically optimal. A careful assessment of both the epidemiological and evolutionary consequences of alternative vaccination strategies is required to determine which individuals should be vaccinated first.

scholarly journals COVID-19: a review of current knowledge regarding exposure, quarantine, isolation and other preventive measures

2021 ◽  
Vol 8 ◽  
pp. 204993612110320
Author(s):  
Robert Rosolanka ◽  
Andres F. Henao-Martinez ◽  
Larissa Pisney ◽  
Carlos Franco-Paredes ◽  
Martin Krsak
Keyword(s):  
Immune Response ◽  
Severe Acute Respiratory Syndrome ◽  
Clinical Response ◽  
Preventive Measures ◽  
Current Knowledge ◽  
Therapeutic Options ◽  
Exposure Control ◽  
Knowledge Gaps ◽  
Vaccination Strategies ◽  
Speed Up

Deeper understanding of the spread, morbidity, fatality, and development of immune response associated with coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, is necessary in order to establish an appropriate epidemiological and clinical response. Exposure control represents a key part of the combat against COVID-19, as the effectiveness of current therapeutic options remains partial. Since the preventive measures have not been sufficiently able to slow down this pandemic, in this article we explore some of the pertinent knowledge gaps, while overall looking to effective vaccination strategies as a way out. Early on, such strategies may need to rely on counting the convalescents as protected in order to speed up the immunization of the whole population.

scholarly journals COVID-19: Mechanisms of Vaccination and Immunity

Vaccines ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 404 ◽  
Author(s):  
Daniel E. Speiser ◽  
Martin F. Bachmann
Keyword(s):  
Immune Responses ◽  
Clinical Management ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Public Life ◽  
High Affinity ◽  
Vaccination Strategies ◽  
Detailed Evaluation ◽  
Pros And Cons

Vaccines are needed to protect from SARS-CoV-2, the virus causing COVID-19. Vaccines that induce large quantities of high affinity virus-neutralizing antibodies may optimally prevent infection and avoid unfavorable effects. Vaccination trials require precise clinical management, complemented with detailed evaluation of safety and immune responses. Here, we review the pros and cons of available vaccine platforms and options to accelerate vaccine development towards the safe immunization of the world’s population against SARS-CoV-2. Favorable vaccines, used in well-designed vaccination strategies, may be critical for limiting harm and promoting trust and a long-term return to normal public life and economy.

Analyzing and Accelerating the Bottlenecks of Training Deep SNNs With Backpropagation

2020 ◽  
Vol 32 (12) ◽  
pp. 2557-2600
Author(s):  
Ruizhi Chen ◽  
Ling Li
Keyword(s):  
Neural Networks ◽  
Training Algorithms ◽  
Minimization Method ◽  
Data Set ◽  
Ultra Low Power ◽  
Training Performance ◽  
Speed Up ◽  
Pros And Cons ◽  
Accuracy Increase ◽  
Initialization Algorithm

Spiking neural networks (SNNs) with the event-driven manner of transmitting spikes consume ultra-low power on neuromorphic chips. However, training deep SNNs is still challenging compared to convolutional neural networks (CNNs). The SNN training algorithms have not achieved the same performance as CNNs. In this letter, we aim to understand the intrinsic limitations of SNN training to design better algorithms. First, the pros and cons of typical SNN training algorithms are analyzed. Then it is found that the spatiotemporal backpropagation algorithm (STBP) has potential in training deep SNNs due to its simplicity and fast convergence. Later, the main bottlenecks of the STBP algorithm are analyzed, and three conditions for training deep SNNs with the STBP algorithm are derived. By analyzing the connection between CNNs and SNNs, we propose a weight initialization algorithm to satisfy the three conditions. Moreover, we propose an error minimization method and a modified loss function to further improve the training performance. Experimental results show that the proposed method achieves 91.53% accuracy on the CIFAR10 data set with 1% accuracy increase over the STBP algorithm and decreases the training epochs on the MNIST data set to 15 epochs (over 13 times speed-up compared to the STBP algorithm). The proposed method also decreases classification latency by over 25 times compared to the CNN-SNN conversion algorithms. In addition, the proposed method works robustly for very deep SNNs, while the STBP algorithm fails in a 19-layer SNN.

A multifactorial analysis of contact-induced change in speech reporting in written White South African English (WSAfE)

2019 ◽  
Vol 24 (1) ◽  
pp. 179-209 ◽  
Author(s):  
HAIDEE KRUGER ◽  
BERTUS VAN ROOY
Keyword(s):  
South African ◽  
Rate Of Change ◽  
Conditional Inference ◽  
Similar Frequency ◽  
Frequency Distributions ◽  
Slowing Down ◽  
Conditional Inference Tree ◽  
Contact Language ◽  
Trajectories Of Change ◽  
A Site

This article presents a corpus analysis of changes over a period of two centuries in speech-reporting constructions in written White South African English (WSAfE), a native variety of English that has been in contact with Afrikaans throughout its history. The analysis is based on register-differentiated comparable diachronic corpora of WSAfE, its parent variety, British English (BrE), and the contact language, Afrikaans. Three related reported-speech constructions are analysed, focusing on changes in the relative frequencies of variants of each construction. These constructions show ongoing change, with similar trajectories of change for WSAfE and BrE in some cases, but divergent trajectories in others. In the latter case, WSAfE and Afrikaans converge on similar frequency distributions, which follow from an accelerated rate of change or a slowing down of the rate of change for particular features in WSAfE in comparison to BrE. Descriptive findings are supported by conditional inference tree modelling. The effect of frequency on reinforcing similar patterns of change in WSAfE and Afrikaans, as well as simplification through the levelling of register differences in WSAfE and Afrikaans are proposed as explanations. The study highlights the importance of converging norms in a multilingual publication industry as a site of contact.

Technology and Disabilities in the Century Ahead

2011 ◽  
pp. 2077-2081
Author(s):  
Ray Kurzweil
Keyword(s):  
20Th Century ◽  
21St Century ◽  
Current Level ◽  
Rate Of Change ◽  
The World ◽  
The Future ◽  
The Disabled ◽  
Speed Up ◽  
Technology Trends ◽  
Over Time

I have been involved in inventing since I was five, and I quickly realized that for an invention to succeed, you have to target the world of the future. But what would the future be like? To find out, I became a student of technology trends and began to develop mathematical models of different technologies: computation, miniaturization, evolution over time. I have been doing that for 25 years, and it has been remarkable to me how powerful and predictive these models are. Now, before I show you some of these models and then try to build with you some of the scenarios for the future—and, in particular, focus on how these will benefit technology for the disabled—I would like to share one trend that I think is particularly profound and that many people fail to take into consideration. It is this: the rate of progress—what I call the “paradigmshift rate”—is itself accelerating. We are doubling this paradigm-shift rate every decade. The whole 20th century was not 100 years of progress as we know it today, because it has taken us a while to speed up to the current level of progress. The 20t h century represented about 20 years of progress in terms of today’s rate. And at today’s rate of change, we will achieve an amount of progress equivalent to that of the whole 20th century in 14 years, then as the acceleration continues, in 7 years. The progress in the 21st century will be about 1,000 times greater than that in the 20th century, which was no slouch in terms of change.

scholarly journals Synergistic coevolution accelerates genome evolution

2021 ◽  
Author(s):  
Daniel Preussger ◽  
Alexander Herbig ◽  
Christian Kost
Keyword(s):  
Molecular Evolution ◽  
Rapid Evolution ◽  
Ecological Interactions ◽  
Metabolic Cooperation ◽  
Interacting Species ◽  
Long Run ◽  
Speed Up ◽  
Key Drivers ◽  
Evolutionary Consequences ◽  
Rapid Emergence

Ecological interactions are key drivers of evolutionary change. Although it is welldocumented that antagonistic coevolution can accelerate molecular evolution, the evolutionary consequences of synergistic coevolution remain poorly understood. Here we show experimentally that also synergistic coevolution can speed up the rate of molecular evolution. Pairs of auxotrophic genotypes of the bacterium Escherichia coli, whose growth depended on a reciprocal exchange of amino acids, were experimentally coevolved, and compared to two control groups of independently growing cells. Coevolution drove the rapid emergence of a strong metabolic cooperation that correlated with a significantly increased number of mutations in coevolved auxotrophs as compared to monoculture controls. These results demonstrate that synergistic coevolution can cause rapid evolution that in the long run may drive diversification of mutualistically interacting species.

scholarly journals A SEIQR Model considering the Effects of Different Quarantined Rates on Worm Propagation in Mobile Internet

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Yonghua Zheng ◽  
Jianhua Zhu ◽  
Chaoan Lai
Keyword(s):  
Mobile Networks ◽  
Manufacturing System ◽  
Reproduction Number ◽  
Vaccination Strategy ◽  
Mobile Internet ◽  
Endemic Equilibrium ◽  
Smart Manufacturing ◽  
Smart Devices ◽  
Asymptotically Stable ◽  
Vaccination Strategies

At present, Wi-Fi is a common medium for connecting smart devices to networks in factories. The application of mobile Internet in smart manufacturing system (SMIS) speeds up the process of smart manufacturing but also increases SMIS vulnerability to worm attack from mobile networks. In this paper, we propose a new SLBQR (susceptible-latent-breaking out-quarantined-recovered) model considering vaccination strategies with temporary immunity and quarantined strategies. Based on basic reproduction number, we give expression of quarantined rate φ and obtain the threshold ϕ∗ of quarantined rate φ such that the worm-free equilibrium is asymptotically stable when ϕ≥ϕ∗, implying that the worm dies out eventually and its attack remains under control; the endemic equilibrium is asymptotically stable when φ<φ∗, namely, the worm is always persistent and spreading within a population. Hence, we give the quarantined strategy ϕ≥ϕ∗ to suppress the spread of virus. In addition, by theoretical analysis, we can conclude that even if the immunity time is unlimited, endemic equilibrium will not become worm-free. In other words, there is a mutation in the virus, which proves that there is no vaccination strategy with permanent immunity. Finally, we simulate our model with different temporary immune time and quarantine rates, and the results verify our theorem.

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