scholarly journals Model Based Estimation of the SARS-CoV-2 Immunization Level in Austria and Consequences for Herd Immunity Effects

2021 ◽  
Author(s):  
Martin Bicher ◽  
Claire Rippinger ◽  
Günter Schneckenreither ◽  
Nadine Weibrecht ◽  
Christoph Urach ◽  
...  
Keyword(s):  
Simulation Model ◽  
Reproduction Number ◽  
Herd Immunity ◽  
Susceptible Population ◽  
Vaccination Programs ◽  
Agent Based ◽  
Model Based ◽  
Systemic Factors ◽  
One Year ◽  
Austrian Population

AbstractSeveral systemic factors indicate, that worldwide herd immunity against COVID-19 will probably not be achieved in 2021. Vaccination programs are limited by availability of doses, the number of people already infected is still too low to have a disease preventing impact and new emerging variants of the virus seem to partially neglect developed antibodies from previous infections. Nevertheless, after one year of COVID-19 observing high numbers of reported cases in most European countries, we might expect that the immunization level should have an impact on the spread of SARS-CoV-2. We used an agent-based simulation model to reproduce the COVID-19 pandemic in Austria to estimate the immunization level of the population as of February 2021. We ran several simulations of an uncontrolled epidemic wave with varying initial immunization scenarios to assess the effect on the effective reproduction number. We also used a classic differential equation SIR-model to cross-validate the simulation model. As of February 2021, 14.7% of the Austrian population has been affected by a SARS-CoV-2 infection which causes a 9% reduction of the effective reproduction number and a 24.7% reduction of the prevalence peak compared to a fully susceptible population. This estimation is now recomputed on a regular basis to publish model based analysis of immunization level in Austria also including the fast growing effects of vaccination programs. This provides substantial information for decision makers to evaluate the necessity of NPI-measures based on the estimated impact of natural and vaccinated immunization.

scholarly journals Herd Immunity in India: A Review

2021 ◽  
Vol 3 (1) ◽  
pp. 18-21
Author(s):  
Sheema Fatima Khan
Keyword(s):  
Basic Reproduction Number ◽  
Reproduction Number ◽  
Natural Infection ◽  
Herd Immunity ◽  
Herd Effect ◽  
Susceptible Population ◽  
Herd Protection ◽  
Cdc Guidelines ◽  
And Control

Herd Immunity is a brilliant solution to tackle and control global pandemics, if taken proper route for immunization such as through vaccination. It is defined as the number of immune individuals against a transmissible virus in a completely susceptible population. The term herd protection or herd effect is the protection to the whole population due to herd immunity. Herd immunity threshold is the minimum proportion of immune population required for herd effect or herd protection. To calculate the threshold, we use basic reproduction number (R0) to measure the rate of transmission of pathogen, in this case SARS-CoV-2. However, a better measure is effective reproduction number (Re). India is major example of herd immunity. Despite strict lockdown and other Covid measure, due to already crowded area the virus could spread fast and to vast majority of people if one of them were to catch it. This explains the steady decline in the number of coronavirus cases in India. At the end, until an approved effective vaccination available, public will still need to follow all the CDC guidelines in order to avoid the large deaths along with natural infection.

scholarly journals Mathematical Epidemiological Model of the Propagation and Prevention of Infectious Diseases Considering COVID-19 Vaccination

2021 ◽  
Author(s):  
Kazumi Omata ◽  
Hiroaki Mitsuya
Keyword(s):  
Infectious Diseases ◽  
Time Scale ◽  
Reproduction Number ◽  
Herd Immunity ◽  
Epidemiological Studies ◽  
Human Populations ◽  
Future Scenarios ◽  
Vaccination Programs ◽  
Asymptotic Nature ◽  
Alternative Approach

Abstract The duration of the necessity of current restrictions and preventive countermeasures against the COVID-19 pandemic is of great concern. While several previous epidemiological studies have discussed controlling the course of the epidemic with regard to social distancing, vaccination, care capacities, and future scenarios, we adopt an alternative approach to provide insights into the time scale of epidemic propagation in human populations. We show that the reproduction number modified by preventive countermeasures Rm implies a threshold R~m to reach the herd immunity level at time Th. While Th varies moderately for large Rm, it increases sharply around Rm=R~m, and Th is infinite below Rm=R~m. The transition region for this increase is minute, demonstrating that prevention of infectious diseases must consider the relatively asymptotic nature of their propagation, which varies unpredictably between steady transmission and explosive outbreaks. These results suggest the continuation of preventive countermeasures to suppress the transmission of COVID-19 for many years; if they were discontinued or reduced such that Rm exceeded R~m, the disease would be transmitted throughout the considered community, and the required herd immunity level would be reached within 250 days if Rm > 1.6. However, the implementation of vaccination programs could drastically alter this dynamic.

scholarly journals Multiagent Models for Forecasting and Identifying Production Processes

2019 ◽  
Vol 8 (12) ◽  
pp. 3807-3809
Keyword(s):  
Simulation Model ◽  
The State ◽  
Parametric Approach ◽  
Agent Based Simulation ◽  
Agent Based ◽  
Active Systems ◽  
Multiagent Simulation ◽  
Model Based ◽  
Production Processes

The article is devoted to the method for creating multiagent models for forecasting and identifying production processes using a structural parametric approach. Using multiagent simulation allows reflecting the state and dynamics of complex active systems of production processes with analysis and forecasting of the quality of the finished product. The methods and algorithms of the structural parametric approach to the implementation of an agent-based simulation model based on the system self-diagnosis are described

scholarly journals New vaccination protocols for the dog and cat: the challenge of today for a better and safer prevention

2017 ◽  
Vol 62 (3) ◽  
pp. 257
Author(s):  
M. E. MYLONAKIS (Μ.Ε. ΜΥΛΩΝΑΚΗΣ) ◽  
A. F. KOUTINAS (Α.Φ. ΚΟΥΤΙΝΑΣ) ◽  
M. SARIDOMICHELAKIS (Μ. ΣΑΡΙΔΟΜΙΧΕΛΑΚΗΣ) ◽  
C. K. KOUTINAS (Χ.Κ. ΚΟΥΤΙΝΑΣ) ◽  
N. SOUBASIS (Ν. ΣΟΥΜΠΑΣΗΣ) ◽  
...  
Keyword(s):  
Adverse Reactions ◽  
Scientific Evidence ◽  
Herd Immunity ◽  
Care Program ◽  
Preventive Health Care ◽  
Time Interval ◽  
Vaccination Programs ◽  
One Year ◽  
The One ◽  
The Individual

Vaccinations are an integral part of a comprehensive preventive health care program targeting to minimize the incidence of major canine and feline infectious diseases. Currently, vaccination practices are re-evaluated globally towards a twofold objective: to strengthen "herd immunity", which depends on the percentage of vaccinated animals in a population, and to reduce the "vaccine load" per animal in order to minimize the vaccine-associated adverse reactions. To this end, the updated canine and feline vaccination guidelines, encourage the vaccination of as many animals as possible, while at the same time classify the vaccines into core, non-core and not recommended. Core vaccines should be administered, if possible, to every dog and cat.Canine parvovirus-2, canine adenovirus-2, canine distemper virus, feline parvovirus, feline calicivirus/herpesvirus-1 and rabies vaccines fall into this category. Non-core vaccines are selectively given to dogs and cats after assessing the risk/benefit ratio. There are also vaccines for which there is currently no sufficient scientific evidence to justify their use. Importantly, after the one-year booster inoculation that follows the completion of the initial puppy/kitten vaccination series, core vaccines should be given no more frequently than every three years, as the duration of the protective immunity far exceeds this time interval. This review focuses on the updated canine and feline vaccination guidelines pertaining to the individual animal as well as to those living in groups. Important questions related to vaccination programs and to relevant adverse reactions are also answered. An effort has been made to align these guidelines according to what is considered a "norm" among the small amimal practitioners in Greece.

scholarly journals Can a COVID-19 vaccination program guarantee the return to a pre-pandemic lifestyle?

2021 ◽  
Author(s):  
Hongjie Yu ◽  
Juan Yang ◽  
Valentina Marziano ◽  
Xiaowei Deng ◽  
Giorgio Guzzetta ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Data Driven ◽  
Vaccination Program ◽  
Natural Immunity ◽  
Epidemic Threshold ◽  
Policy Makers ◽  
Vaccination Programs ◽  
Large Populations ◽  
One Year ◽  
Key Questions

Abstract COVID-19 vaccination programs have been initiated in several countries to control SARS-CoV-2 transmission and return to a pre-pandemic lifestyle. However, understanding when non-pharmaceutical interventions (NPIs) can be lifted as vaccination builds up and how to update priority groups for vaccination in real-time remain key questions for policy makers. To address these questions, we built a data-driven model of SARS-CoV-2 transmission for China. We estimated that, to prevent local outbreaks to escalate to major widespread epidemics, stringent NPIs need to remain in place at least one year after the start of vaccination. Should NPIs be capable to keep the reproduction number (Rt) around 1.3, a vaccination program could reduce up to 99% of COVID-19 burden and bring Rt below the epidemic threshold in about 9 months. Maintaining strict NPIs throughout 2021 is of paramount importance to reduce COVID-19 burden while vaccines are distributed to the population, especially in large populations with little natural immunity.

scholarly journals Estimating asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan: a mathematical modeling study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xi Huo ◽  
Jing Chen ◽  
Shigui Ruan
Keyword(s):  
Disease Transmission ◽  
Large Scale ◽  
Transmission Rate ◽  
Control Strategies ◽  
Herd Immunity ◽  
Antibody Prevalence ◽  
Screening Process ◽  
Vaccination Programs ◽  
Prevalence Level ◽  
The Impact

Abstract Background The COVID-19 outbreak in Wuhan started in December 2019 and was under control by the end of March 2020 with a total of 50,006 confirmed cases by the implementation of a series of nonpharmaceutical interventions (NPIs) including unprecedented lockdown of the city. This study analyzes the complete outbreak data from Wuhan, assesses the impact of these public health interventions, and estimates the asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan. Methods By taking different stages of the outbreak into account, we developed a time-dependent compartmental model to describe the dynamics of disease transmission and case detection and reporting. Model coefficients were parameterized by using the reported cases and following key events and escalated control strategies. Then the model was used to calibrate the complete outbreak data by using the Monte Carlo Markov Chain (MCMC) method. Finally we used the model to estimate asymptomatic and undetected cases and approximate the overall antibody prevalence level. Results We found that the transmission rate between Jan 24 and Feb 1, 2020, was twice as large as that before the lockdown on Jan 23 and 67.6% (95% CI [0.584,0.759]) of detectable infections occurred during this period. Based on the reported estimates that around 20% of infections were asymptomatic and their transmission ability was about 70% of symptomatic ones, we estimated that there were about 14,448 asymptomatic and undetected cases (95% CI [12,364,23,254]), which yields an estimate of a total of 64,454 infected cases (95% CI [62,370,73,260]), and the overall antibody prevalence level in the population of Wuhan was 0.745% (95% CI [0.693%,0.814%]) by March 31, 2020. Conclusions We conclude that the control of the COVID-19 outbreak in Wuhan was achieved via the enforcement of a combination of multiple NPIs: the lockdown on Jan 23, the stay-at-home order on Feb 2, the massive isolation of all symptomatic individuals via newly constructed special shelter hospitals on Feb 6, and the large scale screening process on Feb 18. Our results indicate that the population in Wuhan is far away from establishing herd immunity and provide insights for other affected countries and regions in designing control strategies and planing vaccination programs.

scholarly journals Despite vaccination, China needs non-pharmaceutical interventions to prevent widespread outbreaks of COVID-19 in 2021

2021 ◽  
Author(s):  
Juan Yang ◽  
Valentina Marziano ◽  
Xiaowei Deng ◽  
Giorgio Guzzetta ◽  
Juanjuan Zhang ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Synergetic Effect ◽  
Data Driven ◽  
Natural Immunity ◽  
Epidemic Threshold ◽  
Policy Makers ◽  
Large Populations ◽  
One Year ◽  
Pharmaceutical Interventions

AbstractCOVID-19 vaccination is being conducted in over 200 countries and regions to control SARS-CoV-2 transmission and return to a pre-pandemic lifestyle. However, understanding when non-pharmaceutical interventions (NPIs) can be lifted as immunity builds up remains a key question for policy makers. To address this, we built a data-driven model of SARS-CoV-2 transmission for China. We estimated that, to prevent the escalation of local outbreaks to widespread epidemics, stringent NPIs need to remain in place at least one year after the start of vaccination. Should NPIs alone be capable of keeping the reproduction number (Rt) around 1.3, the synergetic effect of NPIs and vaccination could reduce the COVID-19 burden by up to 99% and bring Rt below the epidemic threshold in about 9 months. Maintaining strict NPIs throughout 2021 is of paramount importance to reduce COVID-19 burden while vaccines are distributed to the population, especially in large populations with little natural immunity.

Research on On-Line Anti-Icing Technology for Carenary along Electrified Railway

2013 ◽  
Vol 676 ◽  
pp. 321-324
Author(s):  
Lei Guo ◽  
Qun Zhan Li
Keyword(s):  
Simulation Model ◽  
Heat Balance ◽  
Normal Operation ◽  
Balance Equations ◽  
Model Based ◽  
Static Var Generator ◽  
On Line ◽  
Electrified Railway ◽  
The Heat Balance

Accidents of icing on catenary have great impacts on normal operation of trains. An on-line anti-icing technology used static var generator (SVG) for catenary was proposed, which can prevent icing formation without interrupting trains normal operation. The heat balance equations for catenary were solved, whose results were compared with data provided by TB/T 3111 and testing show the equation was correct. The simulation model based on Matlab was bulit , whose results and analysis show the correctness of the method.

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