Field Epidemiology Training Program, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjyuku-ku, Tokyo, Japan.
J Infect. 2010 Oct;61(4):284-8. doi: 10.1016/j.jinf.2010.06.019. Epub 2010 Jul 27.
To assess household transmission of pandemic influenza A (H1N1) and effectiveness of postexposure prophylaxis (PEP) of antiviral drugs among household contacts of patients during the first pandemic influenza A (H1N1) outbreak in Osaka, Japan in May 2009.
Active surveillance of patients and their families was conducted. Public Health Center staff visited each home with an infected patient and advised every household member with regard to precautionary measures, and PEP was provided to household contacts to prevent secondary infection. We analyzed the effectiveness of PEP and characteristics of secondary infection.
The secondary attack rate (SAR) among household contacts was 3.7%. The SAR among household contacts without PEP was 26.1%. However, the SAR among those with PEP was 0.6%. Only two of 331 household contacts with PEP became infected. One of the two was infected with an oseltamivir-resistant strain. Analysis of SAR by age group showed that those under 20 years of age were at higher risk than those over 20 (relative risk [RR] = 7.9; 95% confidence interval [CI] = 2.24-27.8). Significant differences with respect to sex, number of household contacts, and use of antiviral medications in the index cases were not observed.
Our present results indicate that PEP is effective for preventing secondary H1N1 infection among household contacts.
评估日本大阪市 2009 年 5 月甲型 H1N1 流感大流行期间甲型 H1N1 流感患者家庭内传播情况，以及家庭接触者暴露后使用抗病毒药物预防（PEP）的效果。
对患者及其家属进行主动监测。公共卫生中心工作人员到每个有感染者的家庭进行家访，就预防措施向每个家庭成员提供建议，并为家庭接触者提供 PEP，以预防二次感染。我们分析了 PEP 的效果和二次感染的特征。
家庭接触者的二次感染率（SAR）为 3.7%。未接受 PEP 的家庭接触者的 SAR 为 26.1%。然而，接受 PEP 的家庭接触者的 SAR 为 0.6%。在 331 名接受 PEP 的家庭接触者中，只有 2 人感染。其中 1 人感染了奥司他韦耐药株。按年龄组分析 SAR 发现，20 岁以下者的风险高于 20 岁以上者（相对风险 [RR] = 7.9；95%置信区间 [CI] = 2.24-27.8）。未观察到与性别、家庭接触人数和索引病例中抗病毒药物使用有关的显著差异。
我们的研究结果表明，PEP 可有效预防家庭接触者的 H1N1 二次感染。
