Department of Women and Child Health, University of Padova, Padova, Italy.
Department of Medical Sciences, University of Ferrara, Ferrara, Italy.
BMC Infect Dis. 2018 Mar 5;18(1):103. doi: 10.1186/s12879-018-3017-9.
Monovalent varicella vaccines have been available in the Veneto Region of Italy since 2004. In 2006, a single vaccine dose was added to the immunisation calendar for children aged 14 months. ProQuad®, a quadrivalent measles-mumps-rubella-varicella vaccine, was introduced in May 2007 and used, among other varicella vaccines, until October 2008. This study aimed to evaluate the effectiveness of a single dose of ProQuad, and the population impact of a vaccination program (VP) against varicella of any severity in children who received a first dose of ProQuad at 14 months of age in the Veneto Region, METHODS: All children born in 2006/2007, i.e., eligible for varicella vaccination after ProQuad was introduced, were retrospectively followed through individual-level data linkage between the Pedianet database (varicella cases) and the Regional Immunization Database (vaccination status). The direct effectiveness of ProQuad was estimated as the incidence rate of varicella in ProQuad-vaccinated children aged < 6 years compared to children with no varicella vaccination from the same birth cohort. The impact of the VP on varicella was measured by comparing children eligible for the VP to an unvaccinated historical cohort from 1997/1998. The vaccine impact measures were: total effect (the combined effect of ProQuad vaccination and being covered by the Veneto VP); indirect effect (the effect of the VP on unvaccinated individuals); and overall effect (the effect of the VP on varicella in the entire population of the Veneto Region, regardless of their vaccination status).
The adjusted direct effectiveness of ProQuad was 94%. The vaccine impact measures total, indirect, and overall effect were 97%, 43%, and 90%, respectively.
These are the first results on the effectiveness and impact of ProQuad against varicella; data confirmed its high effectiveness, based on immunological correlates for protection. Direct effectiveness is our only ProQuad-specific measure; all impact measures refer at least partially to the VP and should be interpreted in the context of high vaccine coverage and the use of various varicella vaccines in this region. The Veneto Region offered a unique opportunity for this study due to an individual data linkage between Pedianet and the Regional Immunization database.
自 2004 年以来，意大利威尼托地区已提供单价水痘疫苗。2006 年，为 14 个月大的儿童添加了一剂疫苗。2007 年 5 月推出了四价麻疹-腮腺炎-风疹-水痘疫苗 ProQuad，并与其他水痘疫苗一起使用，直到 2008 年 10 月。本研究旨在评估 ProQuad 单剂的有效性，以及在威尼托地区，14 个月大的儿童接种一剂 ProQuad 后，任何严重程度的水痘疫苗接种计划（VP）对人群的影响。
所有 2006/2007 年出生的儿童，即 ProQuad 推出后有资格接种水痘疫苗的儿童，通过 Pedianet 数据库（水痘病例）和区域免疫数据库（疫苗接种状况）之间的个体水平数据链接进行回顾性随访。ProQuad 疫苗的直接有效性，是通过比较接种 ProQuad 的<6 岁儿童与同一出生队列中未接种水痘疫苗的儿童的水痘发病率来估计的。通过将符合 VP 条件的儿童与 1997/1998 年的未接种历史队列进行比较，来衡量 VP 对水痘的影响。疫苗影响措施包括：总效应（ProQuad 疫苗接种和威尼托 VP 覆盖的综合效应）；间接效应（VP 对未接种个体的影响）；以及总体效应（VP 对威尼托地区总人口水痘的影响，无论其接种状况如何）。
ProQuad 的调整后直接有效性为 94%。疫苗影响措施的总、间接和总体效果分别为 97%、43%和 90%。
这些是 ProQuad 预防水痘的有效性和影响的首批结果；基于免疫保护相关因素，数据证实了其高有效性。直接有效性是我们唯一的 ProQuad 特异性措施；所有影响措施至少部分涉及 VP，应在高疫苗覆盖率和该地区使用各种水痘疫苗的背景下进行解释。威尼托地区由于 Pedianet 和区域免疫数据库之间的个体数据链接，为这项研究提供了一个独特的机会。
