scholarly journals What pushed Israel out of herd immunity? Modeling COVID-19 spread of Delta and Waning immunity

2021 ◽  
Author(s):  
Hilla De-Leon ◽  
Dvir Aran
Keyword(s):  
Dynamic Model ◽  
Vaccination Campaign ◽  
Herd Immunity ◽  
Aggregate Data ◽  
Spatial Dynamic ◽  
Waning Immunity ◽  
The Impact ◽  
Pharmaceutical Interventions

Following a successful vaccination campaign at the beginning of 2021 in Israel, where approximately 60% of the population were vaccinated with an mRNA BNT162b2 vaccine, it seemed that Israel had crossed the herd immunity threshold (HIT). Nonetheless, Israel has seen a steady rise in COVID-19 morbidity since June 2021, reaching over 1,000 cases per million by August. This outbreak is attributed to several events that came together: the temporal decline of the vaccine's efficacy (VE); lower efficacy of the vaccine against the current Delta (B.1.617.2) variant; highly infectiousness of Delta; and temporary halt of mandated NPIs (non-pharmaceutical interventions) or any combination of the above. Using a novel spatial-dynamic model and recent aggregate data from Israel, we examine the extent of the impact of the Delta variant on morbidity and whether it can solely explain the outbreak. We conclude that both Delta infectiousness and waning immunity could have been able to push Israel above the HIT independently, and thus, to mitigate the outbreak effective NPIs are required. Our analysis cautions countries that once vaccines' will wane a highly infectious spread is expected, and therefore, the expected decline in the vaccine's effectiveness in those countries should be accompanied by another vaccination campaign and effective NPIs

scholarly journals Using a physical model and aggregate data from Israel to estimate the current (July 2021 ) efficacy of the Pfizer-BioNTech vaccine

2021 ◽  
Author(s):  
Hilla De-Leon ◽  
Francesco Pederiva
Keyword(s):  
Physical Model ◽  
Dynamic Model ◽  
Elderly Population ◽  
Age Groups ◽  
Aggregate Data ◽  
High Ability ◽  
Spatial Dynamic ◽  
Severe Morbidity ◽  
Age Dependent ◽  
State Of Israel

From the end of June 2021, the state of Israel, where ~60\% of the population is vaccinated with an mRNA BNT162b2 vaccine, has an increase in the daily morbidity. This increase may be a result of different events: a temporal decline of the vaccine's efficacy; Lower efficacy of the vaccine against the current Delta ( (B.1.617.2) variant (which is now the dominant strain in Israel); A result of lack of social restrictions, a highly contagious variant, or any combination of the above. We found, by using a novel spatial-dynamic model and recent {aggregate} data from Israel, that this new surge of cases is partiality due to a decline in the shielding of those who were vaccinated about six months ago. Also, we found a decrease in the vaccine's efficacy against severe morbidity for the early elderly population compared to the rest of the vaccinated population. These results, which are consistent with recent studies, emphasize the high ability of the model in evaluating the time- and age-dependent efficacy of the vaccine for different age groups and enables to predict the spread of the pandemic as a function of such efficacy.

scholarly journals Rates of SARS-CoV-2 transmission and vaccination impact the fate of vaccine-resistant strains

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Simon A. Rella ◽  
Yuliya A. Kulikova ◽  
Emmanouil T. Dermitzakis ◽  
Fyodor A. Kondrashov
Keyword(s):  
Resistant Strain ◽  
Stochastic Dynamics ◽  
Vaccination Campaign ◽  
Social Consequences ◽  
Intervention Measures ◽  
Current Vaccine ◽  
Transmission Reduction ◽  
Resistant Strains ◽  
The Impact ◽  
Pharmaceutical Interventions

AbstractVaccines are thought to be the best available solution for controlling the ongoing SARS-CoV-2 pandemic. However, the emergence of vaccine-resistant strains may come too rapidly for current vaccine developments to alleviate the health, economic and social consequences of the pandemic. To quantify and characterize the risk of such a scenario, we created a SIR-derived model with initial stochastic dynamics of the vaccine-resistant strain to study the probability of its emergence and establishment. Using parameters realistically resembling SARS-CoV-2 transmission, we model a wave-like pattern of the pandemic and consider the impact of the rate of vaccination and the strength of non-pharmaceutical intervention measures on the probability of emergence of a resistant strain. As expected, we found that a fast rate of vaccination decreases the probability of emergence of a resistant strain. Counterintuitively, when a relaxation of non-pharmaceutical interventions happened at a time when most individuals of the population have already been vaccinated the probability of emergence of a resistant strain was greatly increased. Consequently, we show that a period of transmission reduction close to the end of the vaccination campaign can substantially reduce the probability of resistant strain establishment. Our results suggest that policymakers and individuals should consider maintaining non-pharmaceutical interventions and transmission-reducing behaviours throughout the entire vaccination period.

scholarly journals COVID-19 simulation study—the effect of strict non-pharmaceutical interventions (NPIs) on controlling the spread of COVID-19

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11172
Author(s):  
Amal Alzu’bi ◽  
Sanaa Abu Alasal ◽  
Khalid A. Kheirallah ◽  
Valerie Watzlaf
Keyword(s):  
Local Community ◽  
Preventive Measures ◽  
Short Interval ◽  
Herd Immunity ◽  
Population Movements ◽  
Hypothetical System ◽  
The Government ◽  
High Level ◽  
The Impact ◽  
Pharmaceutical Interventions

Background From the beginning of 2020, COVID-19 infection has changed our lives in many aspects and introduced limitations in the way people interact and communicate. In this paper, we are evaluating the effect of non-pharmaceutical interventions (NPI) in limiting the spread of the Severe Acute Respiratory Syndrome Coronavirus 2 pandemic during a wedding ceremony from Irbid, Northern Jordan. Agent-based modeling was used in a real wedding event that occurred at the beginning of the spread of the pandemic in Jordan. Two infected nationals of Jordan, who arrived in Jordan about a week before the event, initiated the spread of the pandemic within the contact community. Methods In this work, a strict national NPI that the government implemented is developed by using an abstract model with certain characteristics similar to the Jordanian community. Thus, the Jordanian community is represented in terms of ages, occupations, and population movements. After that, the extent of the impact of the NPI measures on the local community is measured. Results We observed the deterioration of the state of society while the epidemic is spreading among individuals in the absence of preventive measures. Also, the results show that the herd immunity case was an epidemic, with a high level of spread among the community with 918 cases during a short interval of time. On the other hand, the preventive measures scenario shows a totally controlled spread with only 74 cases applied on the same interval of time. Furthermore, a convergence in the actual results of the real system with the hypothetical system were detected in the case of applying the strict NPI measures. Finally, strict NPI at the community level following social gatherings seem to be effective measures to control the spread of the COVID- 19 pandemic.

scholarly journals PERCOVID: A Model to Describe COVID Percolation on a Network of Social Relationships

2021 ◽  
Author(s):  
Jean-Francois Mathiot ◽  
Laurent Gerbaud ◽  
Vincent J Breton
Keyword(s):  
Social Interactions ◽  
Social Relationships ◽  
Vaccination Campaign ◽  
Epidemiological Data ◽  
Human Populations ◽  
The Social ◽  
A Site ◽  
The Impact ◽  
Pharmaceutical Interventions ◽  
Typical Scenario

We develop a site-bond percolation model, called PERCOVID, in order to describe the time evolution of COVID epidemics and more generally all epidemics propagating through respiratory tract in human populations. This model is based on a network of social relationships representing interconnected households experiencing governmental non-pharmaceutical interventions. The model successfully accounts for the COVID-19 epidemiological data in metropolitan France from December 2019 up to July 2021. Our model shows the impact of lockdowns and curfews, as well as the influence of the progressive vaccination campaign in order to keep COVID-19 pandemic under the percolation threshold. We illustrate the role played by the social interactions by comparing a typical scenario for the epidemic evolution in France, Germany and Italy during the first wave from January to May 2020. We investigate finally the role played by the alpha and delta variants in the evolution of the epidemic in France till autumn 2021, paying particular attention to the essential role played by the vaccination. Our model predicts that the rise of the epidemic observed in July 2021 will not result in a fourth major epidemic wave in France.

scholarly journals Impact of vaccination and non-pharmaceutical interventions on SARS-CoV-2 dynamics in Switzerland

2021 ◽  
Author(s):  
Andrew J. Shattock ◽  
Epke A. Le Rutte ◽  
Robert P Duenner ◽  
Swapnoleena Sen ◽  
Sherrie L Kelly ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Vaccination Coverage ◽  
Vaccination Campaign ◽  
Population Level ◽  
Morbidity And Mortality ◽  
Transmission Model ◽  
Third Wave ◽  
The Impact ◽  
Pharmaceutical Interventions

As vaccination coverage against SARS-CoV-2 increases amidst the emergence and spread of more infectious and potentially more deadly viral variants, decisions on timing and extent of relaxing effective, but unsustainable, non-pharmaceutical interventions (NPIs) need to be made. An individual-based transmission model of SARS-CoV-2 dynamics, OpenCOVID, was developed to compare the impact of various vaccination and NPI strategies on the COVID-19 epidemic in Switzerland. We estimate that any relaxation of NPIs in March 2021 will lead to increasing cases, hospitalisations, and deaths resulting in a "third wave" in spring and into summer 2021. However, we find a cautious phased relaxation can substantially reduce population-level morbidity and mortality. We find that faster vaccination campaign can offset the size of such a wave, allowing more flexibility for NPI to be relaxed sooner. Our sensitivity analysis revealed that model results are particularly sensitive to the infectiousness of variant B.1.1.7.

scholarly journals A second dramatic rise in seroprevalence rates of SARS-CoV-2 antibodies among adult healthy blood donors in Jordan; have we achieved herd immunity?

2021 ◽  
Author(s):  
Maher A. Sughayer ◽  
Asem Mansour ◽  
Abeer Al Nuirat ◽  
Lina Souan ◽  
Rashid Abdel-Razeq ◽  
...  
Keyword(s):  
Blood Donors ◽  
Healthy Adult ◽  
Vaccination Campaign ◽  
Herd Immunity ◽  
Seroprevalence Rate ◽  
Protein Receptor ◽  
Healthy Donors ◽  
Dramatic Rise ◽  
The Impact ◽  
Second Wave

Objectives: To determine the impact of the second wave of COVID-19 and the vaccination campaign on the seroprevalence rates of SARS-CoV-2 antibodies among healthy blood donors in Jordan. Methods: Sera from 536 healthy adult blood donors collected in June -2021 were tested using a commercially available quantitative assay for the total antibodies including IgG against the spike (S) protein receptor binding domain (RBD) of the SARS-CoV-2. Results: 399 (74.4%) of the donors tested positive for the antibodies of whom 69 (17.3%) were confirmed to have been previously infected, 245(61.4%) have received at least one dose of the vaccine and 123(30.8%) were neither diagnosed nor vaccinated. The seropositive donors were significantly more likely to have been vaccinated or previously infected. Conclusion: The crude seroprevalence rate of 74.4% among this group of healthy donors may be encouraging in terms of approaching herd immunity, however with predominance of the delta variant and the uncertainty regarding the required level of herd immunity this goal appears to be far from full achievement in Jordan.

scholarly journals Highlighting the impact of social relationships on the propagation of respiratory viruses using percolation theory

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jean-François Mathiot ◽  
Laurent Gerbaud ◽  
Vincent Breton
Keyword(s):  
Social Interactions ◽  
Social Relationships ◽  
Vaccination Campaign ◽  
Respiratory Viruses ◽  
Percolation Model ◽  
Human Populations ◽  
A Site ◽  
The Impact ◽  
Epidemic Wave ◽  
Pharmaceutical Interventions

AbstractWe develop a site-bond percolation model, called PERCOVID, in order to describe the time evolution of all epidemics propagating through respiratory tract or by skin contacts in human populations. This model is based on a network of social relationships representing interconnected households experiencing governmental non-pharmaceutical interventions. As a very first testing ground, we apply our model to the understanding of the dynamics of the COVID-19 pandemic in France from December 2019 up to December 2021. Our model shows the impact of lockdowns and curfews, as well as the influence of the progressive vaccination campaign in order to keep COVID-19 pandemic under the percolation threshold. We illustrate the role played by social interactions by comparing two typical scenarios with low or high strengths of social relationships as compared to France during the first wave in March 2020. We investigate finally the role played by the α and δ variants in the evolution of the epidemic in France till autumn 2021, paying particular attention to the essential role played by the vaccination. Our model predicts that the rise of the epidemic observed in July and August 2021 would not result in a new major epidemic wave in France.

scholarly journals Predicting the impact of measles vaccination in England and Wales: model validation and analysis of policy options

1995 ◽  
Vol 114 (2) ◽  
pp. 319-344 ◽  
Author(s):  
H. R. Babad ◽  
D. J. Nokes ◽  
N. J. Gay ◽  
E. Miller ◽  
P. Morgan-Capner ◽  
...  
Keyword(s):  
Vaccine Coverage ◽  
Case Reports ◽  
Vaccination Campaign ◽  
Herd Immunity ◽  
Vaccination Strategy ◽  
School Age Children ◽  
Policy Options ◽  
England And Wales ◽  
Measles Vaccination ◽  
The Impact

SummaryMeasles incidence in England and Wales has fallen to an all-time low. Attention is now focused on preventing local outbreaks, and, in the long run, on the elimination of indigenous measles. A realistic age-structured (RAS) mathematical model of measles transmission is used to reconstruct the impact of measles vaccination in England and Wales from 1968 to the present and to evaluate the merits of future policy options. In general, the predictions of the model show good agreement with long-term age stratified case reports and seroprevalence surveys. The model underestimates the proportion of cases that are notified in 0–2-year-old children. However, recent work suggests a high degree of misdiagnosis in this age group. Projections on the basis of the existing vaccination strategy in the UK suggest that the present level of measles vaccine coverage will be insufficient to eliminate small seasonal outbreaks of measles. This result is, however, sensitive to the assumed level of vaccine efficacy. Explorations of a variety of changes to current vaccination strategy favour a 2-dose schedule with the second dose administered at age 4 years irrespective of vaccination history. A vaccination campaign in school-age children, to reduce deficits in herd immunity, would accelerate progress towards measles elimination.

scholarly journals Critical concepts for COVID-19 Mass Vaccination Site Operations

2021 ◽  
pp. 1-24
Author(s):  
Scott A. Goldberg ◽  
David Callaway ◽  
Daniel Resnick-Ault ◽  
Sujal Mandavia ◽  
Rodrigo Martinez ◽  
...  
Keyword(s):  
Public Health ◽  
Inventory Management ◽  
Communicable Disease ◽  
Vaccination Campaign ◽  
Herd Immunity ◽  
The United States ◽  
Mass Vaccination ◽  
Lessons Learned ◽  
Vaccination Site ◽  
The Impact

Abstract Mass vaccination campaigns have been used effectively to limit the impact of communicable disease on public health. However, the scale of the COVID19 vaccination campaign is unprecedented. Mass vaccination sites consolidate resources and experience into a single entity and are essential to achieving community (“herd”) immunity rapidly, efficiently, and equitably. Healthcare systems, local and regional public health entities, emergency medical services, and private organizations can rapidly come together to solve problems and achieve success. As medical directors at several mass vaccination site across the United States, we describe key mass vaccination site concepts including site selection, operational models, patient flow, inventory management, staffing, technology, reporting, medical oversight, communication, and equity. Lessons learned from experience operating a diverse group of mass vaccination sites will help to inform not only sites operating during the current pandemic but may serve as a blueprint for future outbreaks of highly infectious communicable disease.

332-OR: Determining the Impact of Additional Macronutrients on the Glycemic-Insulin Dynamic Model

Diabetes ◽  
2019 ◽  
Vol 68 (Supplement 1) ◽  
pp. 332-OR
Author(s):  
BOYI JIANG ◽  
YUXIANG ZHONG ◽  
PRATIK AGRAWAL ◽  
TONI L. CORDERO ◽  
ROBERT VIGERSKY
Keyword(s):  
Dynamic Model ◽  
The Impact
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