Kelly Heath, Carville Kylie, Grant Kristina, Jacoby Peter, Tran Thomas, Barr Ian
Epidemiology Unit and Virus Identification Laboratory, Victorian Infectious Diseases Reference Laboratory, Melbourne, Australia.
PLoS One. 2009;4(3):e5079. doi: 10.1371/journal.pone.0005079. Epub 2009 Mar 31.
Influenza vaccines are reviewed each year, and often changed, in an effort to maintain their effectiveness against drifted influenza viruses. There is however no regular review of influenza vaccine effectiveness during, or at the end of, Australian influenza seasons. It is possible to use a case control method to estimate vaccine effectiveness from surveillance data when all patients in a surveillance system are tested for influenza and their vaccination status is known.
METHODOLOGY/PRINCIPAL FINDINGS: Influenza-like illness (ILI) surveillance is conducted during the influenza season in sentinel general practices scattered throughout Victoria, Australia. Over five seasons 2003-7, data on age, sex and vaccination status were collected and nose and throat swabs were offered to patients presenting within three days of the onset of their symptoms. Swabs were tested using a reverse transcriptase polymerase chain reaction (RT-PCR) test. Those positive for influenza were sent to the World Health Organization (WHO) Collaborating Centre for Reference and Research on Influenza where influenza virus culture and strain identification was attempted. We used a retrospective case control design in five consecutive influenza seasons, and estimated influenza vaccine effectiveness (VE) for patients of all ages to be 53% (95% CI 38-64), but 41% (95% CI 19-57) adjusted for age group and year. The adjusted VE for all adults aged at least 20 years, the age groups for whom a benefit of vaccination could be shown, was 51% (95% CI 34-63). Comparison of VE estimates with vaccine and circulating strain matches across the years did not reveal any significant differences.
CONCLUSIONS/SIGNIFICANCE: These estimates support other field studies of influenza vaccine effectiveness, given that theoretical considerations suggest that these values may underestimate true effectiveness, depending on test specificity and the ratio of the influenza ILI attack rate to the non-influenza ILI attack rate. Incomplete recording of vaccination status and under-representation of children in patients from whom a swab was collected limit the data. Improvements have been implemented for prospective studies.
每年都会对流感疫苗进行评估，并且经常更换，以维持其针对变异流感病毒的有效性。然而，在澳大利亚流感季节期间或结束时，并未对流感疫苗的有效性进行定期评估。当监测系统中的所有患者都接受流感检测且其疫苗接种状况已知时，可以使用病例对照方法从监测数据中估计疫苗有效性。
方法/主要发现：在澳大利亚维多利亚州各地的定点全科诊所开展流感季节期间的流感样疾病（ILI）监测。在2003 - 2007年的五个季节里，收集了年龄、性别和疫苗接种状况的数据，并为症状出现三天内就诊的患者采集鼻拭子和咽拭子。使用逆转录聚合酶链反应（RT-PCR）检测对拭子进行检测。流感检测呈阳性的样本被送往世界卫生组织（WHO）流感参考和研究合作中心，尝试进行流感病毒培养和毒株鉴定。我们在连续五个流感季节中采用回顾性病例对照设计，估计所有年龄段患者的流感疫苗有效性（VE）为53%（95%置信区间38 - 64），但按年龄组和年份调整后为41%（95%置信区间19 - 57）。所有年龄至少20岁的成年人（可显示接种疫苗益处的年龄组）的调整后VE为51%（95%置信区间34 - 63）。多年来将VE估计值与疫苗和流行毒株匹配情况进行比较，未发现任何显著差异。
结论/意义：这些估计结果支持了其他关于流感疫苗有效性的实地研究，鉴于理论上的考虑表明，这些数值可能低估了真实有效性，具体取决于检测特异性以及流感ILI发病率与非流感ILI发病率的比率。疫苗接种状况记录不完整以及采集拭子的患者中儿童代表性不足限制了数据。已针对前瞻性研究进行了改进。
