Shankar Manjunath B, Staples J Erin, Meltzer Martin I, Fischer Marc
Division for Preparedness and Emerging Infections, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS C-18, Atlanta, GA 30329, USA.
Arboviral Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, USA.
Vaccine. 2017 May 25;35(23):3143-3151. doi: 10.1016/j.vaccine.2016.11.078. Epub 2017 Apr 26.
West Nile virus (WNV) is the leading cause of domestically-acquired arboviral disease in the United States. Several WNV vaccines are in various stages of development. We estimate the cost-effectiveness of WNV vaccination programs targeting groups at increased risk for severe WNV disease.
We used a mathematical model to estimate costs and health outcomes of vaccination with WNV vaccine compared to no vaccination among seven cohorts, spaced at 10year intervals from ages 10 to 70years, each followed until 90-years-old. U.S. surveillance data were used to estimate WNV neuroinvasive disease incidence. Data for WNV seroprevalence, acute and long-term care costs of WNV disease patients, quality-adjusted life-years (QALYs), and vaccine characteristics were obtained from published reports. We assumed vaccine efficacy to either last lifelong or for 10years with booster doses given every 10years.
There was a statistically significant difference in cost-effectiveness ratios across cohorts in both models and all outcomes assessed (Kruskal-Wallis test p<0.0001). The 60-year-cohort had a mean cost per neuroinvasive disease case prevented of $664,000 and disability averted of $1,421,000 in lifelong model and $882,000 and $1,887,000, respectively in 10-year immunity model; these costs were statistically significantly lower than costs for other cohorts (p<0.0001). Vaccinating 70-year-olds had the lowest cost per death averted in both models at around $4.7 million (95%CI $2-$8 million). Cost per disease case averted was lowest among 40- and 50-year-old cohorts and cost per QALY saved lowest among 60-year cohorts in lifelong immunity model. The models were most sensitive to disease incidence, vaccine cost, and proportion of persons developing disease among infected.
Age-based WNV vaccination program targeting those at higher risk for severe disease is more cost-effective than universal vaccination. Annual variation in WNV disease incidence, QALY weights, and vaccine costs impact the cost effectiveness ratios.
西尼罗河病毒（WNV）是美国本土获得性虫媒病毒病的主要病因。几种WNV疫苗正处于不同的研发阶段。我们评估了针对WNV重症疾病风险增加人群的WNV疫苗接种计划的成本效益。
我们使用一个数学模型来估计WNV疫苗接种与不接种疫苗相比的成本和健康结果，涉及7个队列，年龄从10岁到70岁，间隔10年，每个队列随访至90岁。美国监测数据用于估计WNV神经侵袭性疾病的发病率。WNV血清阳性率、WNV疾病患者的急性和长期护理成本、质量调整生命年（QALY）以及疫苗特性的数据来自已发表的报告。我们假设疫苗效力要么持续终身，要么持续10年，每10年给予加强剂量。
在两个模型以及所有评估的结果中，各队列的成本效益比存在统计学显著差异（Kruskal-Wallis检验p<0.0001）。在终身模型中，60岁队列预防每例神经侵袭性疾病的平均成本为664,000美元，避免残疾的成本为1,421,000美元；在10年免疫模型中，分别为882,000美元和1,887,000美元；这些成本在统计学上显著低于其他队列的成本（p<0.0001）。在两个模型中，为70岁人群接种疫苗预防每例死亡的成本最低，约为470万美元（95%可信区间200万 - 800万美元）。在终身免疫模型中，40岁和50岁队列避免每例疾病的成本最低，60岁队列节省每QALY的成本最低。模型对疾病发病率、疫苗成本以及感染者中发病者的比例最为敏感。
针对重症疾病风险较高人群的基于年龄的WNV疫苗接种计划比普遍接种更具成本效益。WNV疾病发病率、QALY权重和疫苗成本的年度变化会影响成本效益比。
