Infection Prevention and Healthcare Epidemiology Unit, Alfred Health and.
School of Public Health and Preventive Medicine, Monash University, Melbourne.
Clin Infect Dis. 2017 Jun 1;64(11):1564-1572. doi: 10.1093/cid/cix209.
BACKGROUND.: Annual influenza vaccine is recommended for those at greatest risk of severe influenza infection. Recent reports of a negative impact of serial influenza vaccination on vaccine effectiveness (VE) raises concerns about the recommendation for annual influenza vaccines, particularly in persons at greatest risk.
METHODS.: The Influenza Complications Alert Network (FluCAN) is an Australian hospital-based sentinel surveillance program. In this observational study, cases were defined as subjects aged >9 years admitted with influenza confirmed by polymerase chain reaction. Controls were subjects with acute respiratory illness testing negative for influenza. Propensity scores were used to adjust for the likelihood of being vaccinated. VE was calculated as 1 - adjusted odds ratio of vaccination in cases compared with test-negative controls.
RESULTS.: Over 2010-2015, 6223 cases and 6505 controls were hospitalized with confirmed influenza and influenza test-negative acute respiratory illness, respectively. Following stratification by quintile of propensity score, site, and year, VE was estimated to be 43% (95% confidence interval [CI], 37%-49%) overall. VE was estimated to be 51% (95% CI, 45%-57%) in those vaccinated in both the current and previous season, compared with 33% (95% CI, 17%-47%) vaccinated in the current season only and 35% (95% CI, 21%-46%) in the previous season only. Similar results were observed for influenza A/H1N1, influenza A/H3N2, and influenza B strains.
CONCLUSIONS.: Vaccination in both the current and previous seasons was associated with a higher VE against hospitalization with influenza than vaccination in either single season. These findings reinforce current recommendations for annual influenza vaccination, particularly those at greatest risk of influenza disease.
每年都建议为那些感染严重流感风险最高的人接种流感疫苗。最近有报道称，连续接种流感疫苗对疫苗有效性（VE）有负面影响，这让人对推荐每年接种流感疫苗产生了担忧，尤其是对那些感染流感风险最高的人。
流感并发症警报网络（FluCAN）是澳大利亚的一个基于医院的哨点监测计划。在这项观察性研究中，病例定义为年龄>9 岁、经聚合酶链反应确诊为流感的住院患者。对照组为流感检测呈阴性的急性呼吸道疾病患者。采用倾向评分来调整接种疫苗的可能性。VE 计算为病例组中接种疫苗的调整后比值比与流感检测阴性对照组相比。
在 2010 年至 2015 年期间，分别有 6223 例和 6505 例经确诊的流感和流感检测阴性的急性呼吸道疾病住院患者。经过倾向评分五分位数、地点和年份的分层后，总体 VE 估计为 43%（95%置信区间[CI]，37%-49%）。在当前和上一个季节都接种疫苗的人群中，VE 估计为 51%（95% CI，45%-57%），而仅在当前季节接种疫苗的人群中 VE 估计为 33%（95% CI，17%-47%），仅在上一个季节接种疫苗的人群中 VE 估计为 35%（95% CI，21%-46%）。对于甲型 H1N1、甲型 H3N2 和乙型流感病毒株也观察到了类似的结果。
在当前和上一个季节都接种疫苗与仅在当前或上一个季节接种疫苗相比，与因流感住院的 VE 更高。这些发现加强了对每年接种流感疫苗的建议，特别是对那些感染流感风险最高的人。
