The effect of various interventions during a typhoid epidemic. Results of a simulation study

Lange, Heidi; Ulm, K.; Raettig, H; Huber, H

doi:10.1007/bf01641074

Cited by 6 publications

(3 citation statements)

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“…Previous attempts to model the impact of vaccination on the transmission dynamics of typhoid have been made, but these models did not take into account the characteristics of the current and next generation vaccines nor attempt to differentiate between the direct and indirect effects of vaccination [18]–[20]. Our results are qualitatively similar to those of Cvjetanovic et al [18], yet their model considered mass vaccination using whole cell vaccines, which are no longer available.…”

Section: Discussionsupporting

confidence: 66%

Predicting the Impact of Vaccination on the Transmission Dynamics of Typhoid in South Asia: A Mathematical Modeling Study

et al. 2014

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BackgroundModeling of the transmission dynamics of typhoid allows for an evaluation of the potential direct and indirect effects of vaccination; however, relevant typhoid models rooted in data have rarely been deployed.Methodology/Principal FindingsWe developed a parsimonious age-structured model describing the natural history and immunity to typhoid infection. The model was fit to data on culture-confirmed cases of typhoid fever presenting to Christian Medical College hospital in Vellore, India from 2000–2012. The model was then used to evaluate the potential impact of school-based vaccination strategies using live oral, Vi-polysaccharide, and Vi-conjugate vaccines. The model was able to reproduce the incidence and age distribution of typhoid cases in Vellore. The basic reproductive number (R 0) of typhoid was estimated to be 2.8 in this setting. Vaccination was predicted to confer substantial indirect protection leading to a decrease in the incidence of typhoid in the short term, but (intuitively) typhoid incidence was predicted to rebound 5–15 years following a one-time campaign.Conclusions/SignificanceWe found that model predictions for the overall and indirect effects of vaccination depend strongly on the role of chronic carriers in transmission. Carrier transmissibility was tentatively estimated to be low, consistent with recent studies, but was identified as a pivotal area for future research. It is unlikely that typhoid can be eliminated from endemic settings through vaccination alone.

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Section: Discussionsupporting

confidence: 66%

Predicting the Impact of Vaccination on the Transmission Dynamics of Typhoid in South Asia: A Mathematical Modeling Study

et al. 2014

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“…Ten modelling papers were selected for review based on title or abstract. One was discarded as a non-mechanistic time series study [16] , one as it modelled outbreaks in a non-endemic setting [17] , while two papers were of the same model and considered together [18,19] . These are summarised in Tables 1 and 2 .…”

Section: Resultsmentioning

confidence: 99%

A review of typhoid fever transmission dynamic models and economic evaluations of vaccination

Watson

Edmunds

2015

Vaccine

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HighlightsThere are relatively few dynamic models or economic analyses of typhoid vaccination.The relative contribution of carriage to transmission is a key uncertainty.Published economic analyses use static models that omit indirect protection of vaccines.Nevertheless, vaccines appear highly cost-effective against WHO criteria in high-incidence settings.No economic model was found to compare vaccine and sanitation.

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“…There is a large number of mathematical models of typhoid fever dynamics, starting with Cvjetanović et al [5] and including Cvjetanovic et al [6], González-Guzmán [7], Lange et al [8]; see for example Watson & Edmunds [9] and Bakach et al [10] for comprehensive reviews. To accurately capture typhoid fever dynamics, the models include some version of the following compartments: susceptible, infected, chronic, recovered and vaccinated individuals; see for example Bailey [11].…”

Section: Introductionmentioning

confidence: 99%

High endemic levels of typhoid fever in rural areas of Ghana may stem from optimal voluntary vaccination behaviour

et al. 2020

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Typhoid fever has long established itself endemically in rural Ghana despite the availability of cheap and effective vaccines. We used a game-theoretic model to investigate whether the low vaccination coverage in Ghana could be attributed to rational human behaviour. We adopted a version of an epidemiological model of typhoid fever dynamics, which accounted not only for chronic life-long carriers but also for a short-cycle transmission in the immediate environment and a long-cycle transmission via contamination of the water supply. We calibrated the model parameters based on the known incidence data. We found that unless the (perceived) cost of vaccination is negligible, the individually optimal population vaccination rate falls significantly short of the societally optimal population vaccination rate needed to reach herd immunity. We expressed both the herd immunity and the optimal equilibrium vaccination rates in terms of only a few observable parameters such as the incidence rate, demographics, vaccine waning rate and the perceived cost of vaccination relative to the cost of infection. This allowed us not to rely on other uncertain epidemiological model parameters and, in particular, to bypass uncertainties about the role of the carriers in the transmission.

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The effect of various interventions during a typhoid epidemic. Results of a simulation study

Cited by 6 publications

References 1 publication

Predicting the Impact of Vaccination on the Transmission Dynamics of Typhoid in South Asia: A Mathematical Modeling Study

Predicting the Impact of Vaccination on the Transmission Dynamics of Typhoid in South Asia: A Mathematical Modeling Study

A review of typhoid fever transmission dynamic models and economic evaluations of vaccination

High endemic levels of typhoid fever in rural areas of Ghana may stem from optimal voluntary vaccination behaviour

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