تاثیر توزیعی واکسیناسیون روتاویروس در 25 کشور GAVI :برآورد نابرابری ها در اثربخشی سود و زیان

Background Other studies have demonstrated that the impact and cost effectiveness of rotavirus vaccination differs among countries, with greater mortality reduction benefits and lower cost-effectiveness ratios in low-income and high-mortality countries. This analysis combines the results of a country level model of rotavirus vaccination published elsewhere with data from Demographic and Health Surveys on within-country patterns of vaccine coverage and diarrhea mortality risk factors to estimate within-country distributional effects of rotavirus vaccination. The study examined 25 countries eligible for funding through the GAVI Alliance. Methods For each country we estimate the benefits and cost-effectiveness of vaccination for each wealth quintile assuming current vaccination patterns and for a scenario where vaccine coverage is equalized to the highest quintile's coverage. In the case of India, variations in coverage and risk proxies by state were modeled to estimate geographic distributional effects. Results In all countries, rates of vaccination were highest and risks of mortality were lowest in the top two wealth quintiles. However countries differ greatly in the relative inequities in these two underlying variables. Similarly, in all countries examined, the cost-effectiveness ratio for vaccination ($/Disability-Adjusted Life Year averted, DALY) is substantially greater in the higher quintiles (ranging from 2–10 times higher). In all countries, the greatest potential benefit of vaccination was in the poorest quintiles. However, due to reduced vaccination coverage, projected benefits for these quintiles were often lower. Equitable coverage was estimated to result in an 89% increase in mortality reduction for the poorest quintile and a 38% increase overall. Conclusions Rotavirus vaccination is most cost-effective in low-income groups and regions. However in many countries, simply adding new vaccines to existing systems targets investments to higher income children, due to disparities in vaccination coverage. Maximizing health benefits for the poorest children and value for money require increased attention to these distributional effects.

Global and regional level analysis of rotavirus vaccination demonstrates that the impact and cost-effectiveness of vaccination is heterogeneous [1], [2], [3] and [4]. In general there are greater benefits and better cost-effectiveness ratios in low-income countries and regions, primarily due to higher estimated mortality. At the same time, lower vaccination coverage, along with reduced efficacy and great delays in timing mean that the percent reduction in rotavirus burden would be lowest in these countries [5]. However this global pattern of disparities is likely to be repeated within as well as between countries [6]. Poorer households and poorer regions within a particular country are likely to have high diarrhea mortality risk and lower levels of timely vaccination coverage. This suggests that distribution of the benefit, cost-effectiveness and residual (post-vaccination) rotavirus mortality are also likely to differ after vaccine introduction. This paper estimates the geographic and socio-economic distributional effects of rotavirus vaccine introduction within a subset of countries eligible for funding by the GAVI Alliance. This includes the distribution of benefits, cost-effectiveness, and residual (post-vaccine introduction) mortality risk. The main research question is ‘how do outcomes differ across geographic and socio-economic gradients at the regional, national, and sub-national scales?’ Better understanding of distributional effects is essential in tackling the substantial remaining rotavirus mortality burden, even with vaccination. Distributional effects also have implications for decisions about where to invest first, even among and within GAVI-eligible countries. Best practices for economic evaluations of health interventions typically require distributional analyses to assess who within a population is more or less likely to benefit. This is based on an understanding that cost-effectiveness is just one criterion in decision-making and other factors, such as who benefits, also need to be considered. While in practice, few vaccine cost-effectiveness studies directly explore these issues, there is evidence that vaccination can have both pro-poor and anti-poor distributional effects. Bishai et al. demonstrated that near universal measles vaccination in Bangladesh reduced disparities in under-5 mortality [7]. Michaelidis et al. found that efforts in reducing disparities in influenza vaccination among elderly minority groups in the US was moderate to highly cost-effective [8]. Human papillomavirus (HPV) vaccination provides a somewhat different scenario. While the burden of cervical cancer is disproportionately borne by poorer women with limited access to prevention and timely treatment, vaccination programs may similarly miss the target population [9] and [10].

Rotavirus vaccination is most cost-effective in low-income groups and regions. However in many countries, simply adding new vaccines to existing systems targets investments to higher income children, due to disparities in vaccination coverage. Maximizing health benefits for the poorest children and value for money require increased attention to these distributional effects.