Department of Statistics and Mathematics Applied to Economics, Faculty of Economics, University of Pisa, Pisa, Italy.
Am J Epidemiol. 2013 May 15;177(10):1134-42. doi: 10.1093/aje/kws370. Epub 2013 Apr 1.
Varicella-zoster virus (VZV) is the causative agent of both varicella (chickenpox) and herpes zoster (HZ) (shingles). After varicella infection, the virus remains dormant in the host's dorsal ganglia and can reactivate due to waning cell-mediated immunity, causing HZ. Exposure of varicella-immune persons to VZV may boost the host's immune response, resulting in a protective effect against HZ. In this study, we used mathematical models of VZV transmission and HZ development to test the biological hypothesis of "progressive immunity," originally proposed by Hope-Simpson (Proc R Soc Med. 1965;58:9-20), that cell-mediated protection against HZ increases after each episode of exposure to VZV. Predictions from a model incorporating such a hypothesis were compared with those of other concurrent models proposed for explaining HZ epidemiology. The progressive immunity model fits significantly better the age profile of HZ incidence for Finland (years 2000-2006), Italy (2003-2005), Spain (1997-2004), and the United Kingdom (1991-1992), suggesting that this mechanism may be critical in shaping HZ patterns. The model thus validated is an alternative to VZV models currently used to evaluate the impact of mass immunization programs for varicella and therefore extends the range of tools available to assist policy-makers with the present decision paralysis on the introduction of vaccination.
水痘-带状疱疹病毒（VZV）是水痘（带状疱疹）和带状疱疹（带状疱疹）（带状疱疹）的病原体。水痘感染后，病毒潜伏在宿主的背根神经节中，由于细胞介导的免疫力下降而重新激活，导致带状疱疹。水痘免疫者接触 VZV 可能会增强宿主的免疫反应，从而对带状疱疹产生保护作用。在这项研究中，我们使用 VZV 传播和 HZ 发展的数学模型来测试 Hope-Simpson（Proc R Soc Med. 1965;58:9-20）最初提出的“渐进免疫”生物学假设，即每次接触 VZV 后，细胞介导的对 HZ 的保护作用都会增加。将这种假设纳入模型的预测结果与其他同时提出的用于解释 HZ 流行病学的模型进行了比较。渐进免疫模型更符合芬兰（2000-2006 年）、意大利（2003-2005 年）、西班牙（1997-2004 年）和英国（1991-1992 年）的 HZ 发病率年龄分布，表明这种机制可能是形成 HZ 模式的关键。因此，验证的模型是目前用于评估水痘大规模免疫计划影响的 VZV 模型的替代方案，从而扩展了可用于协助决策者应对当前疫苗接种引入决策瘫痪的工具范围。
