Biosecurity Program, The Kirby Institute, University of New South Wales, New South Wales, Sydney, Australia.
School of Public Health and Community Medicine, Faculty of Medicine, University of New South Wales, New South Wales, Sydney, Australia.
PLoS One. 2020 Apr 13;15(4):e0230705. doi: 10.1371/journal.pone.0230705. eCollection 2020.
Influenza continues to cause seasonal epidemics and pandemics in humans. The burden of influenza is underestimated by traditional laboratory-based surveillance, and modelled estimates are required for influenza-attributable morbidity and mortality. We aimed to estimate the influenza-attributable hospitalisation in Australia, by influenza type.
A generalised-additive regression model was used to estimate type- and age-specific influenza-attributable hospitalisation rates per 100,000 population by principal diagnosis in Australia, from 2001 through 2013. Weekly counts of laboratory-confirmed influenza notifications and by type, influenza A and B were used as covariates in the model. Main principal diagnosis categories of interest were influenza and pneumonia and respiratory admissions. A smoothing spline was used to control for unmeasured time varying factors. Results for 2009, in which the pandemic influenza A(H1N1)pdm09 virus circulated, were not included in annual averages and are reported separately.
During the study period, the estimated annual average, all-age, annual respiratory hospitalisation rates attributable to seasonal influenza type A, B and total influenza were 45.4 (95% CI: 34.9, 55.9), 32.6 (95% CI: 22.8, 42.4), and 76.9 (95% CI: 73.6, 80.2) per 100,000 population, respectively. During 2009, the estimated total pandemic influenza-attributable, all-age, respiratory hospitalisation rate was 56.1 (95% CI: 47.4, 64.9) per 100,000. Older adults (≥85 years of age) experienced the highest influenza-attributable hospitalisation rates for both seasonal and 2009 pandemic influenza. Collinearity between influenza A and B time series in some years limited the ability of the model to resolve differences in influenza attribution between the two virus types.
Both seasonal and pandemic influenza caused considerable morbidity in Australia during the years studied, particularly among older adults. The pandemic hospitalisation rate in 2009 was lower than the average overall annual rate for seasonal influenza, but young to middle aged adults experience a hospitalisation rate similar to that of severe seasonal influenza.
流感继续在人类中引发季节性流行和大流行。传统的基于实验室的监测低估了流感的负担，需要对流感相关发病率和死亡率进行模型估计。我们旨在估计澳大利亚按流感类型归因的流感住院人数。
我们使用广义加性回归模型，根据主要诊断，按年龄和流感类型，估算澳大利亚 2001 年至 2013 年期间每 10 万人中流感归因住院率。该模型将每周实验室确诊的流感报告数量和流感 A 型和 B 型的报告数量作为协变量。主要关注的主要诊断类别是流感和肺炎以及呼吸科住院。使用平滑样条控制未测量的随时间变化的因素。2009 年大流行的甲型 H1N1pdm09 病毒循环的数据不包括在年度平均值中，单独报告。
在研究期间，估计的全年龄段年度平均季节性流感 A、B 和总流感归因于呼吸道疾病的住院率分别为 45.4（95%CI：34.9，55.9）、32.6（95%CI：22.8，42.4）和 76.9（95%CI：73.6，80.2）/10 万人。2009 年，估计的大流行流感总归因于呼吸道疾病的全年龄段住院率为 56.1（95%CI：47.4，64.9）/10 万人。老年人（≥85 岁）经历了季节性流感和 2009 年大流行流感的最高流感归因住院率。在某些年份，流感 A 型和 B 型时间序列之间的共线性限制了模型确定两种病毒类型之间流感归因差异的能力。
在研究期间，季节性流感和大流行流感都在澳大利亚造成了相当大的发病率，尤其是在老年人中。2009 年的大流行住院率低于季节性流感的平均年度总发病率，但年轻至中年成年人的住院率与严重季节性流感相似。
