School of Public Health University of Alberta, Edmonton, AB, Canada.
J Clin Virol. 2010 Oct;49(2):90-3. doi: 10.1016/j.jcv.2010.06.015. Epub 2010 Jul 29.
In April 2009, a novel influenza A, subtype H1N1, now referred to as the Pandemic (H1N1) 2009 virus (pH1N1), began circulating in countries around the world. Describing the transmission characteristics of this novel influenza A virus is important to predict current, and future, disease spread. The Public Health response to the first wave of pH1N1 in Alberta focused on the identification and management of secondary cases within households.
The purpose of this study was to describe transmission characteristics of pH1N1 in households in Edmonton, the capital city of Alberta, during the first wave, and to identify the serial interval and secondary attack rate (SAR) in this setting.
This is a prospective analysis of pH1N1 household transmission within 87 urban Canadian households between April 30 and June 9, 2009; with each household having at least one laboratory-confirmed case. The secondary attack rate was calculated in the 262 household contacts using a weighted average by number of susceptible individuals in each household. The serial interval, or time to illness in secondary cases, was analyzed using survival analysis with a Weibull model.
Within the 87 households, 42 (48.3%) had no secondary cases develop; 25 (28.7%) had one secondary case develop; and 20 (22.9%) had more than one secondary case develop. The secondary attack rate did not decrease with increasing household size and households with two members exhibited the lowest secondary attack rate at 14.1%. Children under the age of 19, and individuals with an underlying medical condition, were at increased risk (p<0.05) of becoming a secondary case. The overall secondary attack rate among the 262 susceptible household contacts was 30.2% (95% CI: 12.6-52.2). The median serial interval for pH1N1 transmission was 3.4 days (95% CI: 2.9-3.9).
The identified transmission characteristics of pH1N1 among Canadian households differ slightly from other previously reported North American estimates, but are in keeping with historical transmission rates of pandemic influenza viruses.
2009 年 4 月，一种新型甲型 H1N1 流感病毒，现称为大流行（H1N1）2009 病毒（pH1N1），开始在世界各地传播。描述这种新型甲型流感病毒的传播特征对于预测当前和未来的疾病传播非常重要。艾伯塔省对 pH1N1 的第一波公共卫生反应集中在识别和管理家庭内的继发病例上。
本研究的目的是描述艾伯塔省埃德蒙顿市第一波 pH1N1 在家中的传播特征，并确定该环境中的序列间隔和继发攻击率（SAR）。
这是对 2009 年 4 月 30 日至 6 月 9 日期间 87 个城市加拿大家庭内 pH1N1 家庭传播的前瞻性分析；每个家庭至少有一个实验室确诊的病例。使用每个家庭中易感个体的数量进行加权平均，对 262 个家庭接触者中的继发攻击率进行计算。使用威布尔模型的生存分析分析继发病例的发病时间间隔或疾病时间。
在 87 个家庭中，有 42 个（48.3%）没有继发病例发生；25 个（28.7%）有一个继发病例发生；20 个（22.9%）有多个继发病例发生。继发攻击率并未随家庭规模的增加而降低，而有两个成员的家庭的继发攻击率最低，为 14.1%。年龄在 19 岁以下的儿童和有基础疾病的个体成为继发病例的风险增加（p<0.05）。在 262 个易感家庭接触者中，总继发攻击率为 30.2%（95%CI：12.6-52.2）。pH1N1 传播的中位序列间隔为 3.4 天（95%CI：2.9-3.9）。
在加拿大家庭中确定的 pH1N1 传播特征与其他先前报告的北美的估计略有不同，但与大流行性流感病毒的历史传播率一致。
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