University of Pennsylvania, Department of Medical Ethics and Health Policy, c/o Lauren Counterman, 423 Guardian Drive, Philadelphia, PA 19104, USA.
Seoul National University, Department of Public Health Sciences, Graduate School of Public Health, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, South Korea.
Vaccine. 2021 Jan 3;39(1):158-166. doi: 10.1016/j.vaccine.2020.09.006.
This paper compares cost-effectiveness results from two models of maternal immunization to prevent pertussis in infants in Brazil, one static, one dynamic, to explore when static models are adequate for public health decisions and when the extra effort required by dynamic models is worthwhile.
We defined two scenarios to explore key differences between static and dynamic models, herd immunity and time horizon. Scenario 1 evaluates the incremental cost/DALY of maternal acellular pertussis (aP) immunization as routine infant vaccination coverage ranges from low/moderate up to, and above, the threshold at which herd immunity begins to eliminate pertussis. Scenario 2 compares cost-effectiveness estimates over the models' different time horizons. Maternal vaccine prices of $9.55/dose (base case) and $1/dose were evaluated.
The dynamic model shows that maternal immunization could be cost-saving as well as life-saving at low levels of infant vaccination coverage. When infant coverage reaches the threshold range (90-95%), it is expensive: the dynamic model estimates that maternal immunization costs $2 million/DALY at infant coverage > 95% and maternal vaccine price of $9.55/dose; at $1/dose, cost/DALY is $200,000. By contrast, the static model estimates costs/DALY only modestly higher at high than at low infant coverage. When the models' estimates over their different time horizons are compared at infant coverage < 90-95%, their projections fall in the same range.
Static models may serve to explore an intervention's cost-effectiveness against infectious disease: the direction and principal drivers of change were the same in both models. When, however, an intervention too small to have significant herd immunity effects itself, such as maternal aP immunization, takes place against a background of vaccination in the rest of the population, a dynamic model is crucial to accurate estimates of cost-effectiveness. This finding is particularly important in the context of widely varying routine infant vaccination rates globally.
Clinical Trial registry name and registration number: Not applicable.
本文比较了两种预防巴西婴儿百日咳的母体免疫模型的成本效益结果，一种是静态模型，另一种是动态模型，以探讨何时静态模型适用于公共卫生决策，以及动态模型所需的额外努力是否值得。
我们定义了两种情景来探索静态和动态模型之间的关键差异，即群体免疫和时间范围。情景 1 评估了在常规婴儿接种覆盖率从低/中度增加到并高于群体免疫开始消除百日咳的阈值范围内，母体无细胞百日咳（aP）免疫接种的增量成本/残疾调整生命年（DALY）。情景 2 比较了模型不同时间范围内的成本效益估计。评估了母体疫苗价格为 9.55 美元/剂（基本情况）和 1 美元/剂的情况。
动态模型表明，在婴儿接种覆盖率较低的情况下，母体免疫接种既可以节省生命，也可以节省成本。当婴儿覆盖率达到阈值范围（90-95%）时，它的成本很高：动态模型估计，当婴儿覆盖率>95%且母体疫苗价格为 9.55 美元/剂时，母体免疫接种的成本/DALY 为 200 万美元；当疫苗价格为 1 美元/剂时，成本/DALY 为 20 万美元。相比之下，静态模型在高婴儿覆盖率下的成本/DALY 估计值仅略高于低婴儿覆盖率。当在婴儿覆盖率<90-95%的情况下比较模型在不同时间范围内的估计值时，它们的预测结果落在相同范围内。
静态模型可以用于探索干预措施对传染病的成本效益：在两种模型中，干预措施的方向和变化的主要驱动因素是相同的。然而，当一种干预措施本身太小，无法产生显著的群体免疫效果，例如母体 aP 免疫接种，而在人群中的其他部分进行疫苗接种时，动态模型对于准确估计成本效益至关重要。这一发现尤其重要，因为全球范围内常规婴儿接种率差异很大。
临床试验注册名称和注册号：不适用。
