Model Comparisons of the Effectiveness and Cost-Effectiveness of Vaccination: A Systematic Review of the Literature

OBJECTIVES

To describe all published articles that have conducted comparisons of model-based effectiveness and cost-effectiveness results in the field of vaccination. Specific objectives were to 1) describe the methodologies used and 2) identify the strengths and limitations of the studies.

METHODS

We systematically searched MEDLINE and Embase databases for studies that compared predictions of effectiveness and cost-effectiveness of vaccination of two or more mathematical models. We categorized studies into two groups on the basis of their data source for comparison (previously published results or new simulation results) and performed a qualitative synthesis of study conclusions.

RESULTS

We identified 115 eligible articles (only 5% generated new simulations from the reviewed models) examining the effectiveness and cost-effectiveness of vaccination against 14 pathogens (69% of studies examined human papillomavirus, influenza, and/or pneumococcal vaccines). The goal of most of studies was to summarize evidence for vaccination policy decisions, and cost-effectiveness was the most frequent outcome examined. Only 33%, 25%, and 3% of studies followed a systematic approach to identify eligible studies, assessed the quality of studies, and performed a quantitative synthesis of results, respectively. A greater proportion of model comparisons using published studies followed a systematic approach to identify eligible studies and to assess their quality, whereas more studies using new simulations performed quantitative synthesis of results and identified drivers of model conclusions. Most comparative modeling studies concluded that vaccination was cost-effective.

CONCLUSIONS

Given the variability in methods used to conduct/report comparative modeling studies, guidelines are required to enhance their quality and transparency and to provide better tools for decision making.

Pertussis re-emergence in the post-vaccination era

BACKGROUND

Resurgence of pertussis in the post-vaccination era has been reported in Western countries. A shift of cases from school-age children to adolescents, adults and children under 1 year of age has been described in the last decade, and mortality rates in infants are still sustained. We aimed to review and discuss the possible vaccination strategies which can be adopted in order to improve the pertussis control, by searches of Pubmed, and websites of US and European Centers for Disease Control and Prevention, between 1st January 2002, and 1st March 2013.

DISCUSSION

The following vaccination strategies have been retrieved and analysed: the cocooning strategy, the immunization of pregnant women and newborns, vaccination programs for preschool children, adolescents, adults and health-care workers. Cost-effectiveness studies provide some contrasting data, mainly supporting both maternal vaccination and cocooning. Adolescent and/or adult vaccination seems to be cost-effective, however data from observational studies suggest that this vaccination strategy, used alone, leads to a reduced pertussis burden globally, but does not affect the disease incidence in infants. Moreover, substantial logistical and economic difficulties have to be overcome to vaccinate the largest number of individuals.

SUMMARY

The simultaneous use of more than one strategy, including cocooning strategy plus vaccination of adolescents and adults, seems to be the most reasonable preventive measure. The development of new highly immunogenic and efficacious pertussis vaccines continues to be a primary objective for the control of pertussis.