Scheduling of measles vaccination in low-income countries: Projections of a dynamic model

Bauch, Chris T.; Szusz, Emily K.; Garrison, Louis P.

doi:10.1016/j.vaccine.2009.04.079

Cited by 38 publications

(45 citation statements)

References 39 publications

(55 reference statements)

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“…The majority of measles deaths occurs in resource-poor countries [28]. Simulation studies illustrate the importance of measles vaccination in these populations [6], [35], [36], with estimated benefits similar to our findings. Studies also highlight the importance of program quality and supplemental immunization activities.…”

Section: Discussionsupporting

confidence: 82%

Quantifying Child Mortality Reductions Related to Measles Vaccination

et al. 2010

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BackgroundThis study characterizes the historical relationship between coverage of measles containing vaccines (MCV) and mortality in children under 5 years, with a view toward ongoing global efforts to reduce child mortality.Methodology/Principal FindingsUsing country-level, longitudinal panel data, from 44 countries over the period 1960–2005, we analyzed the relationship between MCV coverage and measles mortality with (1) logistic regressions for no measles deaths in a country-year, and (2) linear regressions for the logarithm of the measles death rate. All regressions allowed a flexible, non-linear relationship between coverage and mortality. Covariates included birth rate, death rates from other causes, percent living in urban areas, population density, per-capita GDP, use of the two-dose MCV, year, and mortality coding system. Regressions used lagged covariates, country fixed effects, and robust standard errors clustered by country. The likelihood of no measles deaths increased nonlinearly with higher MCV coverage (ORs: 13.8 [1.6–122.7] for 80–89% to 40.7 [3.2–517.6] for ≥95%), compared to pre-vaccination risk levels. Measles death rates declined nonlinearly with higher MCV coverage, with benefits accruing more slowly above 90% coverage. Compared to no coverage, predicted average reductions in death rates were −79% at 70% coverage, −93% at 90%, and −95% at 95%.Conclusions/Significance40 years of experience with MCV vaccination suggests that extremely high levels of vaccination coverage are needed to produce sharp reductions in measles deaths. Achieving sustainable benefits likely requires a combination of extended vaccine programs and supplementary vaccine efforts.

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Section: Discussionsupporting

confidence: 82%

Quantifying Child Mortality Reductions Related to Measles Vaccination

et al. 2010

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“…A more detail study of the effects of seasonal variation (with the degree of seasonality) and climate change are also of interest. We do not include seasonal forcing in the baseline model since there are little data that can be used to estimate country-specific estimates of seasonal forcing amplitudes (Bauch et al 2009). However, it is observed that including seasonal contact of the form bðtÞ ¼ b þ b sinð2pt=365Þ; damping oscillations occur in Fig.…”

Section: Resultsmentioning

confidence: 99%

Optimal Control and Sensitivity Analysis of an Influenza Model with Treatment and Vaccination

Khamis²,

et al. 2010

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We formulate and analyze the dynamics of an influenza pandemic model with vaccination and treatment using two preventive scenarios: increase and decrease in vaccine uptake. Due to the seasonality of the influenza pandemic, the dynamics is studied in a finite time interval. We focus primarily on controlling the disease with a possible minimal cost and side effects using control theory which is therefore applied via the Pontryagin's maximum principle, and it is observed that full treatment effort should be given while increasing vaccination at the onset of the outbreak. Next, sensitivity analysis and simulations (using the fourth order Runge-Kutta scheme) are carried out in order to determine the relative importance of different factors responsible for disease transmission and prevalence. The most sensitive parameter of the various reproductive numbers apart from the death rate is the inflow rate, while the proportion of new recruits and the vaccine efficacy are the most sensitive parameters for the endemic equilibrium point.

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“…This type of model has been shown to agree reasonably well with time series of infection incidence many paediatric infectious diseases even when age structure is not included [12,20,23,24]. Individuals can be Susceptible, Infectious, Recovered, or Vaccinated with immunity, hence we refer to it as a SIRV model.…”

Section: Methodsmentioning

confidence: 94%

The potential impact of immunization campaign budget re-allocation on global eradication of paediatric infectious diseases

Fitzpatrick

Bauch

2011

BMC Public Health

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BackgroundThe potential benefits of coordinating infectious disease eradication programs that use campaigns such as supplementary immunization activities (SIAs) should not be over-looked. One example of a coordinated approach is an adaptive "sequential strategy": first, all annual SIA budget is dedicated to the eradication of a single infectious disease; once that disease is eradicated, the annual SIA budget is re-focussed on eradicating a second disease, etc. Herd immunity suggests that a sequential strategy may eradicate several infectious diseases faster than a non-adaptive "simultaneous strategy" of dividing annual budget equally among eradication programs for those diseases. However, mathematical modeling is required to understand the potential extent of this effect.MethodsOur objective was to illustrate how budget allocation strategies can interact with the nonlinear nature of disease transmission to determine time to eradication of several infectious diseases under different budget allocation strategies. Using a mathematical transmission model, we analyzed three hypothetical vaccine-preventable infectious diseases in three different countries. A central decision-maker can distribute funding among SIA programs for these three diseases according to either a sequential strategy or a simultaneous strategy. We explored the time to eradication under these two strategies under a range of scenarios.ResultsFor a certain range of annual budgets, all three diseases can be eradicated relatively quickly under the sequential strategy, whereas eradication never occurs under the simultaneous strategy. However, moderate changes to total SIA budget, SIA frequency, order of eradication, or funding disruptions can create disproportionately large differences in the time and budget required for eradication under the sequential strategy. We find that the predicted time to eradication can be very sensitive to small differences in the rate of case importation between the countries. We also find that the time to eradication of all three diseases is not necessarily lowest when the least transmissible disease is targeted first.ConclusionsRelatively modest differences in budget allocation strategies in the near-term can result in surprisingly large long-term differences in time required to eradicate, as a result of the amplifying effects of herd immunity and the nonlinearities of disease transmission. More sophisticated versions of such models may be useful to large international donors or other organizations as a planning or portfolio optimization tool, where choices must be made regarding how much funding to dedicate to different infectious disease eradication efforts.

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Scheduling of measles vaccination in low-income countries: Projections of a dynamic model

Cited by 38 publications

References 39 publications

Quantifying Child Mortality Reductions Related to Measles Vaccination

Quantifying Child Mortality Reductions Related to Measles Vaccination

Optimal Control and Sensitivity Analysis of an Influenza Model with Treatment and Vaccination

The potential impact of immunization campaign budget re-allocation on global eradication of paediatric infectious diseases

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