BC Centre for Disease Control, Vancouver, BC, Canada.
Influenza Other Respir Viruses. 2012 May;6(3):e54-62. doi: 10.1111/j.1750-2659.2012.00344.x. Epub 2012 Mar 2.
To characterize the first-wave epidemiologic features of influenza-like illness (ILI) associated with the novel pandemic A/H1N1 [A(H1N1)pdm09] virus.
We used generalized linear mixed models (GLMM) to assess risk factors and non-parametric and/or parametric distributions to estimate attack rates, secondary attack rates (SAR), duration of illness, and serial interval during a laboratory-confirmed community outbreak of A(H1N1)pdm09 clustered around on-reserve residents and households of an elementary school in rural British Columbia, Canada, in late April/early May 2009. ILI details were collected as part of outbreak investigation by community telephone survey in early June 2009.
Overall, 92/408 (23%) of participants developed ILI and 36/408 (9%) experienced medically attended ILI (MAILI). The overall SAR in households was 22%: highest among participants 1-4 years of age (yoa) (50%) followed by < 1 yoa (38%), 5-8 yoa (20%), 10-19 yoa (13%), 20-49 yoa (20%), and 50-64 yoa (0%). The median serial interval was estimated at 3·5 days (95% CI: 2·1-5·1). In multivariable GLMM analysis, having a chronic condition (OR: 2·58; 95% CI: 1·1-6·04), younger age [1-8 yoa: OR: 4·63; 95% CI: 2·25-9·52; 9-19 yoa: OR: 1·95; 95% CI: 0·97-3·9 (referent: ≥ 20 yoa)] and receipt of 2008-2009 influenza vaccine (OR: 2·68; 95% CI: 1·37-5·25) were associated with increased risk of ILI. Median duration of illness was 9 days, longer among those with chronic conditions (21 days). Median time to seeking care after developing illness was 4·5 days. On-reserve participants had higher chronic conditions, household density, ILI, MAILI, and SAR.
During a community outbreak of A(H1N1)pdm09-related illness, we identified substantial clinical ILI attack rates exceeding 20% with secondary household attack rates as high as 50% in young children. The serial interval was short suggesting a narrow period to prevent transmission.
描述与新型甲型 H1N1 [A(H1N1)pdm09] 病毒相关的流感样疾病 (ILI) 的第一波流行病学特征。
我们使用广义线性混合模型 (GLMM) 来评估风险因素，使用非参数和/或参数分布来估计发病率、二代发病率 (SAR)、疾病持续时间和病毒潜伏期。该研究在加拿大不列颠哥伦比亚省农村的一个小学及其周围保留区居民中爆发了新型甲型 H1N1pdm09 病毒，我们对此次社区暴发进行了调查。潜伏期的详细信息是在 2009 年 6 月初进行社区电话调查时作为暴发调查的一部分收集的。
共有 408 名参与者中的 92 名（23%）出现 ILI，408 名参与者中的 36 名（9%）出现医疗性 ILI（MAILI）。家庭中的总 SAR 为 22%：年龄在 1-4 岁的参与者中最高（50%），其次是 < 1 岁（38%）、5-8 岁（20%）、10-19 岁（13%）、20-49 岁（20%）和 50-64 岁（0%）。估计的中位病毒潜伏期为 3.5 天（95%CI：2.1-5.1）。在多变量 GLMM 分析中，患有慢性疾病（OR：2.58；95%CI：1.1-6.04）、年龄较小[1-8 岁：OR：4.63；95%CI：2.25-9.52；9-19 岁：OR：1.95；95%CI：0.97-3.9（参考值：≥ 20 岁）]和接种 2008-2009 年流感疫苗（OR：2.68；95%CI：1.37-5.25）与 ILI 风险增加相关。疾病持续时间的中位数为 9 天，患有慢性疾病的参与者持续时间更长（21 天）。从出现症状到寻求医疗的中位时间为 4.5 天。保留区的参与者具有更高的慢性病、家庭密度、ILI、MAILI 和 SAR。
在新型甲型 H1N1pdm09 相关疾病的社区暴发中，我们发现发病率很高，临床 ILI 发病率超过 20%，幼儿的家庭二代发病率高达 50%。病毒潜伏期较短，表明预防传播的时间很短。
