Dataset Information

Periodicity of varicella-zoster virus in the presence of immune boosting and clinical reinfection with varicella.

ABSTRACT:

Background

Clinical reinfection with varicella is normally ignored in mathematical transmission models as it is considered too rare to be important.

Methods

We apply basic bifurcation analysis to a simple mathematical model of varicella-zoster virus (VZV) transmission incorporating reinfection.

Results

We demonstrate that under certain conditions this model can exhibit periodic behaviour as opposed to what is observed in VZV models that ignore the possibility of repeat varicella attacks. Periodicity can be induced by a combination of immune boosting and reinfection while the impact of zoster (shingles) recurrence on the onset of periodicity is negligible.

Conclusions

Our results suggest that mathematical models of VZV may benefit from inclusion of repeat varicella.

SUBMITTER: Korostil IA

PROVIDER: S-EPMC4399247 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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Publications

Periodicity of varicella-zoster virus in the presence of immune boosting and clinical reinfection with varicella.

Korostil Igor A IA Wood James G JG Regan David G DG

Theoretical biology & medical modelling 20150411

<h4>Background</h4>Clinical reinfection with varicella is normally ignored in mathematical transmission models as it is considered too rare to be important.<h4>Methods</h4>We apply basic bifurcation analysis to a simple mathematical model of varicella-zoster virus (VZV) transmission incorporating reinfection.<h4>Results</h4>We demonstrate that under certain conditions this model can exhibit periodic behaviour as opposed to what is observed in VZV models that ignore the possibility of repeat vari ...[more]

PMID: 25886473

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Project description:BackgroundA controversy exists about the potential effect of childhood varicella vaccination on Herpes Zoster (HZ) incidence. Mathematical models projected temporary HZ incidence increase after vaccine introduction that was not confirmed by real-world evidence. These models assume that absence of contacts with infected children would prevent exogenous boosting of Varicella-Zoster-Virus (VZV) immunity and they do not include an endogenous VZV immunity-boosting mechanism following asymptomatic VZV reactivation. This study aims to explore the effect of various assumptions on exogenous and endogenous VZV immunity-boosting on HZ incidence in the general population after introduction of routine childhood varicella vaccination.MethodsAn age-structured dynamic transmission model was adapted and fitted to the seroprevalence of varicella in France in absence of vaccination using the empirical contact matrix. A two-dose childhood varicella vaccination schedule was introduced at 12 and 18 months. Vaccine efficacy was assumed at 65%/95% (dose 1/dose 2), and coverage at 90%/80% (dose 1/dose 2). Exogenous boosting intensity was based on assumptions regarding HZ-immunity duration, age-dependent boosting effect, and HZ reactivation rates fitted to observed HZ incidence. Endogenous boosting was the same as pre-vaccination exogenous boosting but constant over time, whilst exogenous boosting depended on the force of infection. Five scenarios were tested with different weightings of exogenous (Exo) - endogenous (Endo) boosting: 100%Exo-0%Endo, 75%Exo-25%Endo, 50%Exo-50%Endo, 25%Exo-75%Endo, 0%Exo-100%Endo.ResultsHZ incidence before varicella vaccination, all ages combined, was estimated at 3.96 per 1000 person-years; it decreased by 64% by year 80 post vaccine introduction, for all boosting assumptions. The 100%Exo-0%Endo boosting scenario, predicted an increase in HZ incidence for the first 21 years post vaccine introduction with a maximum increase of 3.7% (4.1/1000) at year 9. However, with 0%Exo-100%Endo boosting scenario an immediate HZ decline was projected. The maximum HZ incidence increases at 10, 3, and 2 years post vaccination were 1.8% (75%Exo-25%Endo), 0.8% (50%Exo-50%Endo) and 0.2% (25%Exo-75%Endo), respectively.ConclusionsAssuming modest levels of endogenous boosting, the increase in HZ incidence following childhood varicella vaccination was smaller and lasted for a shorter period compared with 100%Exo-0%Endo boosting assumption. Endogenous boosting mechanism could partly explain the divergence between previous HZ-incidence projections and real-world evidence.

Dataset Information

Periodicity of varicella-zoster virus in the presence of immune boosting and clinical reinfection with varicella.

Background

Methods

Results

Conclusions

Publications

Periodicity of varicella-zoster virus in the presence of immune boosting and clinical reinfection with varicella.

Similar Datasets

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