Department of Family, Population & Preventive Medicine, Program in Public Health, Health Sciences Center, Stony Brook University, Stony Brook, NY, USA.
Bagamian Scientific Consulting, Gainesville, FL, USA.
Lancet Glob Health. 2023 Jun;11(6):e892-e902. doi: 10.1016/S2214-109X(23)00050-5.
Linear growth is an important outcome of child development with implications for economic productivity. Enteric infections, particularly Shigella, have been linked to linear growth faltering (LGF). However, benefits from potential reductions in LGF are rarely included in economic analyses of enteric infections. We aimed to quantify the economic benefits of vaccination related to reduced Shigella-attributable disease and associated LGF compared with the net costs of a vaccine programme.
In this benefit-cost analysis, we modelled productivity benefits in 102 low-income and middle-income countries that had recent stunting estimates available, at least one Shigella-attributable death annually, and available economic data, particularly on gross national income and growth rate projections. We modelled benefits strictly related to linear growth improvements and no other benefits associated with reducing diarrhoeal burden. The effect size in each country was calculated as shifts in height-for-age Z score (HAZ), representing population average changes for preventing Shigella-attributable less-severe diarrhoea and moderate-to-severe diarrhoea separately for children younger than 5 years. Benefits data were calculated per country and combined with estimated net costs of the vaccine programme in the form of benefit-cost ratios (BCRs); BCRs above parity, or $1 in benefits per $1 in costs (with a 10% margin representing borderline results: 1·10:1), were considered cost-beneficial. Countries were aggregated for analysis by WHO region, World Bank income category, and eligibility for support from Gavi, the Vaccine Alliance.
In the base-case scenario, all regions exhibited cost-beneficial results, with the South-East Asia region and Gavi-eligible countries exhibiting the highest BCRs (21·67 for the South-East Asia region and 14·45 for Gavi-eligible countries), and the Eastern Mediterranean region yielding the lowest BCRs (2·90). All regions exhibited cost-beneficial results from vaccination, except in more conservative scenarios (eg, those assuming early retirement ages and higher discount rates). Our findings were sensitive to assumed returns for increased height, assumptions about vaccine efficacy against linear growth detriments, the anticipated shift in HAZ, and discount rate. Incorporating the productivity benefits of LGF reduction into existing cost-effectiveness estimates resulted in longer-term cost-savings in nearly all regions.
LGF is a secondary outcome of Shigella infection and reduction in LGF is not often quantified as a health or economic benefit of vaccination. However, even under conservative assumptions, a Shigella vaccine only moderately effective against LGF could pay for itself from productivity gains alone in some regions. We recommend that LGF be considered in future models assessing the economic and health impacts of interventions preventing enteric infections. Further research is needed on vaccine efficacy against LGF to inform such models.
Bill & Melinda Gates Foundation, Wellcome Trust.
线性生长是儿童发育的一个重要结果，对经济生产力有影响。肠道感染，特别是志贺氏菌，与线性生长迟缓（LGF）有关。然而，肠道感染相关的潜在 LGF 减少带来的益处很少被纳入肠道感染的经济分析中。我们旨在量化与减少志贺氏菌相关疾病和相关 LGF 相关的疫苗接种的经济效益，与疫苗接种方案的净成本相比。
在这项效益成本分析中，我们对最近有发育迟缓估计值、每年至少有一起志贺氏菌归因死亡和可用经济数据（特别是国民总收入和增长率预测）的 102 个低收入和中等收入国家进行了建模。我们严格按照线性生长改善的效益进行建模，不考虑与降低腹泻负担相关的其他任何益处。每个国家的效应大小均以身高年龄 Z 评分（HAZ）的变化表示，代表预防志贺氏菌引起的轻度腹泻和中重度腹泻的人群平均变化，分别针对 5 岁以下的儿童。效益数据按国家计算，并与疫苗方案的估计净成本相结合，以效益成本比（BCR）的形式表示；效益成本比高于平价（每 1 美元成本带来 1 美元效益，有 10%的利润率代表边缘结果：1.10:1）被认为是有益的。通过世界卫生组织区域、世界银行收入类别和是否有资格获得疫苗联盟 Gavi 的支持，对国家进行了汇总分析。
在基本情况下，所有地区均显示出成本效益结果，东南亚地区和有资格获得 Gavi 支持的国家的效益成本比最高（东南亚地区为 21.67，有资格获得 Gavi 支持的国家为 14.45），而东地中海地区的效益成本比最低（2.90）。除了更保守的情况（例如，假设提前退休年龄和更高的贴现率）外，所有地区的疫苗接种都显示出成本效益。我们的研究结果对假设的身高回报、对线性生长损害的疫苗效力的假设、预期的 HAZ 变化以及贴现率很敏感。将 LGF 减少的生产力效益纳入现有的成本效益估计中，几乎在所有地区都导致了长期的成本节约。
LGF 是志贺氏菌感染的次要结果，减少 LGF 通常不作为疫苗接种的健康或经济效益进行量化。然而，即使在保守的假设下，一种对 LGF 只有中等效力的志贺氏菌疫苗仅通过生产力收益就可以在某些地区自行支付。我们建议在未来评估预防肠道感染的干预措施的经济和健康影响的模型中考虑 LGF。需要进一步研究疫苗对 LGF 的效力，以为这些模型提供信息。
比尔和梅琳达盖茨基金会，惠康信托基金会。
