4Flu-an individual based simulation tool to study the effects of quadrivalent vaccination on seasonal influenza in Germany
4Flu-an individual based simulation tool to study the effects of quadrivalent vaccination on seasonal influenza in Germany
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DOI：
10.1186/1471-2334-14-365
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发表时间：
2014-07-03
影响因子：
3.7
通讯作者：
Schmidt-Ott, Ruprecht
中科院分区：
文献类型：
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作者：
Eichner, Martin;Schwehm, Markus;Schmidt-Ott, Ruprecht
背景：流感疫苗含有甲型和B型流感抗原，每年调整一次，以匹配流行病毒的特征。在德国，流感B病毒属于B/Yamagata谱系，但自2001年以来，抗原性不同的B/维多利亚谱系一直在共同传播。三价流感疫苗（TIV）含有两种A亚型A（H3 N2）和A（H1N1）的抗原，但只有一种B谱系，导致频繁的疫苗错配。自2012年以来，WHO一直在推荐来自两个B谱系的疫苗株，为四价流感疫苗（QIV）铺平了道路。方法：使用基于个体的模拟工具，模拟4种流感病毒株的伴随传播，比较TIV和QIV对感染发生率的影响。个人连接在一个动态发展的年龄相关的接触网络的基础上POLYMOD矩阵;他们的年龄分布再现德国的人口统计数据和预测。该模型考虑了母体保护、增强现有免疫力、免疫力丧失和B谱系之间的交叉免疫事件。校准到所观察到的年感染率为10.6%的年轻成年人中产生的基本繁殖数为1.575。每年10月和11月进行疫苗接种，覆盖率取决于接种者的年龄、风险状况和以前的疫苗接种状况。新的漂移变体在随机时间点引入，导致部分人群的保护性免疫力突然丧失，偶尔导致疫苗效力降低。模拟运行50年，其中前30年用于初始化。在最后的20年中，个人接受TIV或QIV，使用镜像simulation approach.Results：使用QIV，平均年感染率可以从8，943，000减少到8，548，000，即减少395，000例感染，预防了11.2%的所有B型流感感染，这些感染仍然与TIV一起发生（95%CI：10.7-11.8%）。使用较低的B谱系交叉保护比基线的60%，流感B感染的数量增加，另外防止QIV的数量可以是5.5倍high.Conclusions：接种TIV疫苗大大降低了流感的发病率相比，没有接种疫苗。根据假定的B谱系交叉保护程度，QIV可进一步降低B型流感发病率11- 33%。
Background: Influenza vaccines contain Influenza A and B antigens and are adjusted annually to match the characteristics of circulating viruses. In Germany, Influenza B viruses belonged to the B/Yamagata lineage, but since 2001, the antigenically distinct B/Victoria lineage has been co-circulating. Trivalent influenza vaccines (TIV) contain antigens of the two A subtypes A(H3N2) and A(H1N1), yet of only one B lineage, resulting in frequent vaccine mismatches. Since 2012, the WHO has been recommending vaccine strains from both B lineages, paving the way for quadrivalent influenza vaccines (QIV).Methods: Using an individual-based simulation tool, we simulate the concomitant transmission of four influenza strains, and compare the effects of TIV and QIV on the infection incidence. Individuals are connected in a dynamically evolving age-dependent contact network based on the POLYMOD matrix; their age-distribution reproduces German demographic data and predictions. The model considers maternal protection, boosting of existing immunity, loss of immunity, and cross-immunizing events between the B lineages. Calibration to the observed annual infection incidence of 10.6% among young adults yielded a basic reproduction number of 1.575. Vaccinations are performed annually in October and November, whereby coverage depends on the vaccinees' age, their risk status and previous vaccination status. New drift variants are introduced at random time points, leading to a sudden loss of protective immunity for part of the population and occasionally to reduced vaccine efficacy. Simulations run for 50 years, the first 30 of which are used for initialization. During the final 20 years, individuals receive TIV or QIV, using a mirrored simulation approach.Results: Using QIV, the mean annual infection incidence can be reduced from 8,943,000 to 8,548,000, i.e. by 395,000 infections, preventing 11.2% of all Influenza B infections which still occur with TIV (95% CI: 10.7-11.8%). Using a lower B lineage cross protection than the baseline 60%, the number of Influenza B infections increases and the number additionally prevented by QIV can be 5.5 times as high.Conclusions: Vaccination with TIV substantially reduces the Influenza incidence compared to no vaccination. Depending on the assumed degree of B lineage cross protection, QIV further reduces Influenza B incidence by 11-33%.