Age-Structured Epidemic with Adaptive Vaccination Strategy: Scalar-Renewal Equation Approach

2021 ◽  
pp. 591-599
Author(s):  
Aubain Nzokem ◽  
Neal Madras
Keyword(s):  
Vaccination Strategy ◽  
Renewal Equation ◽  
Equation Approach ◽  
Age Structured

scholarly journals Modelling the impact of extended vaccination strategies on the epidemiology of pertussis

2011 ◽  
Vol 140 (8) ◽  
pp. 1503-1514 ◽  
Author(s):  
M. H. ROZENBAUM ◽  
R. De VRIES ◽  
H. H. LE ◽  
M. J. POSTMA
Keyword(s):  
Booster Dose ◽  
Deterministic Model ◽  
Natural Infection ◽  
Age Groups ◽  
Vaccination Strategy ◽  
Booster Vaccination ◽  
Sensitivity Analyses ◽  
Wide Range ◽  
Age Structured ◽  
The Impact

SUMMARYThe aim of this study was to investigate the optimal pertussis booster vaccination strategy for The Netherlands. A realistic age-structured deterministic model was designed. Assuming a steady-state situation and correcting for underreporting, the model was calibrated using notification data from the period 1996–2000. Several sensitivity analyses were performed to explore the impact of different assumptions for parameters surrounded by uncertainty (e.g. duration of protection after natural infection, underreporting factors, and transmission probabilities). The optimal age of an additional booster dose is in the range of 10–15 years, and implementation of this booster dose will reduce both symptomatic and asymptomatic infections, although the incidence of symptomatic infections in older age groups will increase. The impact of the different assumptions used in the model was in general limited. We conclude that over a wide range of assumptions, an additional booster dose can reduce the incidence of pertussis in the population.

A renewal-equation approach to the dynamics of stage-grouped populations

1986 ◽  
Vol 79 (2) ◽  
pp. 185-197 ◽  
Author(s):  
FranÇois Houllier ◽  
Jean-Dominique Lebreton
Keyword(s):  
Renewal Equation ◽  
Equation Approach

scholarly journals Influence of heterogeneous age-group contact patterns on critical vaccination rates for herd immunity to SARS-CoV-2

2021 ◽  
Author(s):  
Joan Saldana ◽  
Caterina M Scoglio
Keyword(s):  
Vaccination Coverage ◽  
Herd Immunity ◽  
Age Groups ◽  
Social Contact ◽  
Vaccination Strategy ◽  
Primary Concern ◽  
Vaccination Rates ◽  
Contact Patterns ◽  
Group Contact ◽  
Age Structured

Currently, several western countries have more than half of their population fully vaccinated against COVID-19. At the same time, some of them are experiencing a fourth or even a fifth wave of cases, most of them concentrated in sectors of the populations whose vaccination coverage is lower than the average. So, the initial scenario of vaccine prioritization has given way to a new one where achieving herd immunity is the primary concern. Using an age-structured vaccination model with waning immunity, we show that, under a limited supply of vaccines, a vaccination strategy based on minimizing the basic reproduction number allows for the deployment of a number of vaccine doses lower than the one required for maximizing the vaccination coverage. Such minimization is achieved by giving greater protection to those age groups that, for a given social contact pattern, have smaller fractions of susceptible individuals at the endemic equilibrium without vaccination, that is, to those groups that are more vulnerable to infection.

scholarly journals Vaccine Effects on Susceptibility and Symptomatology Can Change the Optimal Allocation of COVID-19 Vaccines: South Korea as an Example

2021 ◽  
Vol 10 (13) ◽  
pp. 2813
Author(s):  
Wongyeong Choi ◽  
Eunha Shim
Keyword(s):  
South Korea ◽  
Optimal Allocation ◽  
Age Groups ◽  
Vaccination Strategy ◽  
Epidemiological Data ◽  
Health Interventions ◽  
Risk Of Disease ◽  
Age Structured ◽  
Effective Public Health ◽  
Country Specific

The approved coronavirus disease (COVID-19) vaccines reduce the risk of disease by 70–95%; however, their efficacy in preventing COVID-19 is unclear. Moreover, the limited vaccine supply raises questions on how they can be used effectively. To examine the optimal allocation of COVID-19 vaccines in South Korea, we constructed an age-structured mathematical model, calibrated using country-specific demographic and epidemiological data. The optimal control problem was formulated with the aim of finding time-dependent age-specific optimal vaccination strategies to minimize costs related to COVID-19 infections and vaccination, considering a limited vaccine supply and various vaccine effects on susceptibility and symptomatology. Our results suggest that “susceptibility-reducing” vaccines should be relatively evenly distributed among all age groups, resulting in more than 40% of eligible age groups being vaccinated. In contrast, “symptom-reducing” vaccines should be administered mainly to individuals aged 20–29 and ≥60 years. Thus, our study suggests that the vaccine profile should determine the optimal vaccination strategy. Our findings highlight the importance of understanding vaccine’s effects on susceptibility and symptomatology for effective public health interventions.

scholarly journals Data-driven estimate of SARS-CoV-2 herd immunity threshold in populations with individual contact pattern variations

2021 ◽  
Author(s):  
Dan Lu ◽  
Alberto Aleta ◽  
Marco Ajelli ◽  
Romualdo Pastor-Satorras ◽  
Alessandro Vespignani ◽  
...  
Keyword(s):  
Herd Immunity ◽  
Vaccination Strategy ◽  
Mass Vaccination ◽  
Data Driven ◽  
Vaccination Programs ◽  
Contact Patterns ◽  
Social Mixing ◽  
Age Structured ◽  
Individual Contact ◽  
Induced Immunity

The development of efficacious vaccines has made it possible to envision mass vaccination programs aimed at suppressing SARS-CoV-2 transmission around the world. Here we use a data-driven age-structured multilayer representation of the population of 34 countries to estimate the disease induced immunity threshold, accounting for the contact variability across individuals. We show that the herd immunization threshold of random (un-prioritized) mass vaccination programs is generally larger than the disease induced immunity threshold. We use the model to test two additional vaccine prioritization strategies, transmission-focused and age-based, in which individuals are inoculated either according to their behavior (number of contacts) or infection fatality risk, respectively. Our results show that in the case of a sterilizing vaccine the behavioral strategy achieves herd-immunity at a coverage comparable to the disease-induced immunity threshold, but it appears to have inferior performance in averting deaths than the risk vaccination strategy. The presented results have potential use in defining the effects that the heterogeneity of social mixing and contact patterns has on herd immunity levels and the deployment of vaccine prioritization strategies.

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