Canadian Center for Vaccinology, IWK Health Centre and Nova Scotia Health Authority, Dalhousie University, 5850/5980 University Ave, Halifax, Nova Scotia, B3K 6R8, Canada.
GSK, King of Prussia, Current affiliation: Novavax Vaccines, Washington, DC, USA.
BMC Infect Dis. 2017 Dec 29;17(1):805. doi: 10.1186/s12879-017-2905-8.
The Serious Outcomes Surveillance (SOS) Network was established to monitor seasonal influenza complications among hospitalized Canadian adults and to assess the effectiveness of influenza vaccination against severe outcomes. Here we report age- and strain-specific vaccine effectiveness (VE) in preventing severe outcomes during a season characterized by mixed outbreaks of four different influenza strains.
This prospective, multicentre, test-negative case-control study evaluated the VE of trivalent influenza vaccine (TIV) in the prevention of laboratory-confirmed influenza-hospitalization in adults aged ≥16 years (all adults) and adults aged 16-64 years (younger adults). The SOS Network identified hospitalized patients with diagnoses potentially attributable to influenza during the 2011/12 influenza season. Swabs collected at admission were tested by reverse transcriptase polymerase chain reaction (RT PCR) or viral culture to discriminate influenza cases (positive) from controls (negative). VE was calculated as 1-odds ratio (OR) of vaccination in cases versus controls × 100.
Overall, in all adults, the unadjusted and adjusted VEs of TIV against influenza-hospitalization were 41.8% (95% Confidence Interval [CI]: 26.0, 54.3), and 42.8% (95% CI: 23.8, 57.0), respectively. In younger adults (16-64 years), the unadjusted and adjusted VEs of TIV against influenza-hospitalization were 35.8% (95% CI: 4.5, 56.8) and 33.2% (95% CI: -6.7, 58.2), respectively. In the all adults group, adjusted VE against influenza A/H1N1 was 72.5% (95% CI: 30.5, 89.1), against A/H3N2 was 86.1% (95% CI: 40.1, 96.8), against B/Victoria was 40.5% (95% CI: -28.9, 72.6), and against B/Yamagata was 32.3% (95% CI: -8.3, 57.7). The adjusted estimate of early season VE (from November 1 to March 11) was 54.4% (95% CI: 29.7-70.4), which was higher than late season (from March 11 to May 25) VE estimate (VE: 29.7%, 95% CI: -5.3, 53.1).
These results suggest that TIV was highly effective against A viruses and moderately effective against B viruses during a mild season characterised by co-circulation of four influenza strains in Canada. Findings underscore the need to provide VE assessment by subtype/lineage as well as the timing of vaccination (early season vs late season) to accurately evaluate vaccine performance and thus guide public health decision-making.
ClinicalTrials.gov Identifier: NCT01517191. Registration was retrospective and the date of registration was January 17, 2012.
严重后果监测（SOS）网络成立的目的是监测加拿大住院成年患者季节性流感并发症，并评估流感疫苗对严重后果的有效性。在此，我们报告了在一个以四种不同流感株混合爆发为特征的季节中，针对严重后果的年龄和株特异性疫苗有效性（VE）。
这项前瞻性、多中心、病例对照研究评估了三价流感疫苗（TIV）在预防≥16 岁（所有成年人）和 16-64 岁（年轻人）成年人中实验室确诊的流感住院方面的 VE。SOS 网络在 2011/12 流感季节期间确定了可能与流感相关的住院患者。入院时采集的拭子通过逆转录酶聚合酶链反应（RT-PCR）或病毒培养进行检测，以区分流感病例（阳性）和对照组（阴性）。VE 通过接种疫苗的病例与对照组的比值比（OR）计算得出，结果乘以 100。
总体而言，在所有成年人中，TIV 对流感住院的未经调整和调整 VE 分别为 41.8%（95%置信区间[CI]：26.0，54.3）和 42.8%（95% CI：23.8，57.0）。在年轻人（16-64 岁）中，TIV 对流感住院的未经调整和调整 VE 分别为 35.8%（95% CI：4.5，56.8）和 33.2%（95% CI：-6.7，58.2）。在所有成年人组中，对甲型流感 H1N1 的调整 VE 为 72.5%（95% CI：30.5，89.1），对甲型流感 H3N2 为 86.1%（95% CI：40.1，96.8），对乙型流感 Victoria 为 40.5%（95% CI：-28.9，72.6），对乙型流感 Yamagata 为 32.3%（95% CI：-8.3，57.7）。早期季节 VE（从 11 月 1 日至 3 月 11 日）的调整估计值为 54.4%（95% CI：29.7-70.4），高于晚期季节（从 3 月 11 日至 5 月 25 日）VE 估计值（VE：29.7%，95% CI：-5.3，53.1）。
这些结果表明，在加拿大四种流感株共同流行的温和季节，TIV 对 A 病毒高度有效，对 B 病毒中度有效。研究结果强调需要按亚型/谱系以及接种疫苗的时间（早期季节与晚期季节）提供 VE 评估，以准确评估疫苗效果，从而指导公共卫生决策。
ClinicalTrials.gov 标识符：NCT01517191。注册是回顾性的，注册日期为 2012 年 1 月 17 日。
