Characteristics of the studies included.

ObjectiveIn Europe, the age indication for the MF59-adjuvanted quadrivalent influenza vaccine (aQIV) has recently been extended from ≥65 to ≥50 years. Considering that the earliest approval of its trivalent formulation (aTIV) in Italy was for people aged ≥12 years, we aimed to systematically appraise data on the immunogenicity, efficacy, and safety of aTIV/aQIV in non-elderly adults.MethodsA systematic literature review was conducted according to the available guidelines and studies were searched in MEDLINE, Biological Abstracts, Web of Science, Cochrane Library and clinical trial registries. Studies on absolute and relative immunogenicity, efficacy, effectiveness, and safety of aTIV/aQIV in non-elderly adults (ResultsTwenty-four publications were analyzed. aTIV/aQIV was more immunogenic than non-adjuvanted vaccines towards vaccine-like strains: the absolute differences in seroconversion rates were 8.8% (95% CI: 3.7%, 14.0%), 13.1% (95% CI: 6.7%, 19.6%) and 11.7% (95% CI: 7.2%, 16.2%) for A(H1N1), A(H3N2), and B strains, respectively. This immunogenicity advantage was more pronounced in immunosuppressed adults. Additionally, aTIV/aQIV was more immunogenic than non-adjuvanted counterparts towards heterologous A(H3N2) strains with a 10.7% (95% CI: 3.2%, 18.2%) difference in seroconversion rates. Data on antibody persistence and efficacy were limited and inconclusive. Overall, aTIV/aQIV was judged safe and well tolerated, although reactogenic events were more frequent in aTIV/aQIV recipients versus comparators. Serious adverse events were uncommon and no difference (risk ratio 1.02; 95% CI: 0.64, 1.63) between aTIV/aQIV and non-adjuvanted formulations was found.ConclusionsIn non-elderly adults, aTIV/aQIV is safe and generally more immunogenic than non-adjuvanted standard-dose vaccines.

研究目的
在欧洲，MF59佐剂四价流感疫苗（MF59-adjuvanted quadrivalent influenza vaccine, aQIV）的接种年龄适应证近期已从≥65岁扩展至≥50岁。鉴于MF59佐剂三价流感疫苗（trivalent formulation, aTIV）最早在意大利获批的适用人群为≥12岁人群，本研究旨在系统评价非老年成人中aTIV/aQIV的免疫原性、保护效力与安全性。

研究方法
本研究依据现有指南开展系统综述，在MEDLINE、生物学文摘（Biological Abstracts）、Web of Science、Cochrane图书馆及临床试验注册库中检索相关研究，纳入针对非老年成人中aTIV/aQIV的绝对与相对免疫原性、保护效力、实际效果及安全性的研究。

研究结果
本研究共纳入24篇文献进行分析。相较于非佐剂流感疫苗，aTIV/aQIV对疫苗匹配毒株的免疫原性更优：A(H1N1)、A(H3N2)及B型毒株的血清转换率绝对差值分别为8.8%（95%CI：3.7%，14.0%）、13.1%（95%CI：6.7%，19.6%）及11.7%（95%CI：7.2%，16.2%）。该免疫原性优势在免疫抑制成人中更为显著。此外，针对异型A(H3N2)毒株，aTIV/aQIV的免疫原性亦优于非佐剂对照疫苗，血清转换率差值为10.7%（95%CI：3.2%，18.2%）。关于抗体持久性与保护效力的数据较为有限且结论不明确。总体而言，尽管aTIV/aQIV接种者的反应原性事件发生率高于对照疫苗，但aTIV/aQIV整体安全性良好且耐受性佳。严重不良事件较为罕见，aTIV/aQIV与非佐剂剂型间未观察到显著差异（风险比1.02；95%CI：0.64，1.63）。

研究结论
在非老年成人中，aTIV/aQIV安全性良好，且总体免疫原性优于非佐剂标准剂量流感疫苗。