Modeling the economic benefits of an AIDS vaccine

Health economic evaluation of current vaccination strategies and new vaccines against tuberculosis: a systematic review

Introduction: Bacillus Calmette-Guérin (BCG) is the only licensed vaccine for tuberculosis, but its effectiveness is limited and varies by age. New candidate vaccines are currently being investigated. In response to the declining incidence of TB, practices relating to BCG vaccination have changed in various countries in recent years. A valid cost-effectiveness study is therefore needed in order to assist decision-makers in the implementation of cost-effective strategies for BCG vaccination. Areas covered: Studies involving economic evaluations of BCG vaccination were reviewed in order to present current findings concerning a range of BCG vaccination strategies in a variety of regions, target populations, and vaccine types. The Quality of Health Economic Studies (QHES) instrument was used to assess the quality of the studies included in the analysis. Expert opinion: Most of the studies showed a favorable economic profile of BCG vaccination. Selective strategies seem the most cost-effective option for low-incidence areas. Varying results on revaccination strategies did not lead to any conclusive finding on the cost-effectiveness of the strategies. A novel vaccine - either a BCG replacement or booster vaccine that provides better protection, especially in adults - has the potential to enhance the cost-effectiveness of vaccinating against tuberculosis.

Addressing viral resistance through vaccines

Antimicrobial resistance is a serious healthcare concern affecting millions of people around the world. Antiviral resistance has been viewed as a lesser threat than antibiotic resistance, but it is important to consider approaches to address this growing issue. While vaccination is a logical strategy, and has been shown to be successful many times over, next generation viral vaccines with a specific goal of curbing antiviral resistance will need to clear several hurdles including vaccine design, evaluation and implementation. This article suggests that a new model of vaccination may need to be considered: rather than focusing on public health, this model would primarily target sectors of the population who are at high risk for complications from certain infections.

Impact and cost-effectiveness of new tuberculosis vaccines in low- and middle-income countries

To help reach the target of tuberculosis (TB) disease elimination by 2050, vaccine development needs to occur now. We estimated the impact and cost-effectiveness of potential TB vaccines in low- and middle-income countries using an age-structured transmission model. New vaccines were assumed to be available in 2024, to prevent active TB in all individuals, to have a 5-y to lifetime duration of protection, to have 40-80% efficacy, and to be targeted at "infants" or "adolescents/adults." Vaccine prices were tiered by income group (US $1.50-$10 per dose), and cost-effectiveness was assessed using incremental cost per disability adjusted life year (DALY) averted compared against gross national income per capita. Our results suggest that over 2024-2050, a vaccine targeted to adolescents/adults could have a greater impact than one targeted at infants. In low-income countries, a vaccine with a 10-y duration and 60% efficacy targeted at adolescents/adults could prevent 17 (95% range: 11-24) million TB cases by 2050 and could be considered cost-effective at $149 (cost saving to $387) per DALY averted. If targeted at infants, 0.89 (0.42-1.58) million TB cases could be prevented at $1,692 ($634-$4,603) per DALY averted. This profile targeted at adolescents/adults could be cost-effective at $4, $9, and $20 per dose in low-, lower-middle-, and upper-middle-income countries, respectively. Increased investments in adult-targeted TB vaccines may be warranted, even if only short duration and low efficacy vaccines are likely to be feasible, and trials among adults should be powered to detect low efficacies.

Cost-effectiveness and economic benefits of vaccines in low- and middle-income countries: a systematic review

BACKGROUND

Public health interventions that prevent mortality and morbidity have greatly increased over the past decade. Immunization is one of these preventive interventions, with a potential to bring economic benefits beyond just health benefits. While vaccines are considered to be a cost-effective public health intervention, implementation has become increasingly challenging. As vaccine costs rise and competing priorities increase, economic evidence is likely to play an increasingly important role in vaccination decisions.

METHODS

To assist policy decisions today and potential investments in the future, we provide a systematic review of the literature on the cost-effectiveness and economic benefits of vaccines in low- and middle-income countries from 2000 to 2010. The review identified 108 relevant articles from 51 countries spanning 23 vaccines from three major electronic databases (Pubmed, Embase and Econlit).

RESULTS

Among the 44 articles that reported costs per disability-adjusted life year (DALY) averted, vaccines cost less than or equal to $100 per DALY averted in 23 articles (52%). Vaccines cost less than $500 per DALY averted in 34 articles (77%), and less than $1000 per DALY averted in 38 articles (86%) in one of the scenarios. 24 articles (22%) examined broad level economic benefits of vaccines such as greater future wage-earning capacity and cost savings from averting disease outbreaks. 60 articles (56%) gathered data from a primary source. There were little data on long-term and societal economic benefits such as morbidity-related productivity gains, averting catastrophic health expenditures, growth in gross domestic product (GDP), and economic implications of demographic changes resulting from vaccination.

CONCLUSIONS

This review documents the available evidence and shows that vaccination in low- and middle-income countries brings important economic benefits. The cost-effectiveness studies reviewed suggest to policy makers that vaccines are an efficient investment. This review further highlights key gaps in the available literature that would benefit from additional research, especially in the area of evaluating the broader economic benefits of vaccination in the developing world.

Is a HIV vaccine a viable option and at what price? An economic evaluation of adding HIV vaccination into existing prevention programs in Thailand

Background

This study aims to determine the maximum price at which HIV vaccination is cost-effective in the Thai healthcare setting. It also aims to identify the relative importance of vaccine characteristics and risk behavior changes among vaccine recipients to determine how they affect this cost-effectiveness.

Methods

A semi-Markov model was developed to estimate the costs and health outcomes of HIV prevention programs combined with HIV vaccination in comparison to the existing HIV prevention programs without vaccination. The estimation was based on a lifetime horizon period (99 years) and used the government perspective. The analysis focused on both the general population and specific high-risk population groups. The maximum price of cost-effective vaccination was defined by using threshold analysis; one-way and probabilistic sensitivity analyses were performed. The study employed an expected value of perfect information (EVPI) analysis to determine the relative importance of parameters and to prioritize future studies.

Results

The most expensive HIV vaccination which is cost-effective when given to the general population was 12,000 Thai baht (US$1 = 34 Thai baht in 2009). This vaccination came with 70% vaccine efficacy and lifetime protection as long as risk behavior was unchanged post-vaccination. The vaccine would be considered cost-ineffective at any price if it demonstrated low efficacy (30%) and if post-vaccination risk behavior increased by 10% or more, especially among the high-risk population groups. The incremental cost-effectiveness ratios were the most sensitive to change in post-vaccination risk behavior, followed by vaccine efficacy and duration of protection. The EVPI indicated the need to quantify vaccine efficacy, changed post-vaccination risk behavior, and the costs of vaccination programs.

Conclusions

The approach used in this study differentiated it from other economic evaluations and can be applied for the economic evaluation of other health interventions not available in healthcare systems. This study is important not only for researchers conducting future HIV vaccine research but also for policy decision makers who, in the future, will consider vaccine adoption.

Modeling the Impact of a Partially Effective HIV Vaccine on HIV Infection and Death Among Women and Infants in South Africa

OBJECTIVE

To assess the potential impact over 10 years of a partially effective HIV vaccine in a cohort of 15-year-old adolescent girls in South Africa in terms of HIV infections and deaths prevented in mothers and infants.

METHODS

A computer simulation was constructed using a population of all 15-year-old adolescent girls in South Africa followed for 10 years. A partially effective vaccine is introduced into this population with the ability to reduce the HIV incidence rates of the adolescents and vertical transmission to their infants through birth and breast-feeding. At the end of this 10 year period, the number of HIV infections and death prevented in adolescents and infants is analyzed.

RESULTS

Using a 5% HIV incidence rate, a 50% effective vaccine decreases the number of HIV cases among adolescents by 57,653 (28.7%) and the number of cases among infants by 13,765 (28.9%) over 10 years. In addition, assuming a vaccine cost of $20 per dose, the vaccination program can save approximately $120 million for the South African government over 10 years.

CONCLUSION

A partially effective HIV vaccine has an important role in HIV prevention in adolescents and infants in South Africa irrespective of other public policy implementations.