N Komiya1, Y Gu, H Kamiya, Y Yahata, Y Yasui, K Taniguchi, N Okabe. 1. Field Epidemiology Training Program, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjyuku-ku, Tokyo, Japan. kominobu@nih.go.jp
Abstract
OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: Our present results indicate that PEP is effective for preventing secondary H1N1 infection among household contacts.
OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: Our present results indicate that PEP is effective for preventing secondary H1N1 infection among household contacts.
Authors: Lincoln L H Lau; Hiroshi Nishiura; Heath Kelly; Dennis K M Ip; Gabriel M Leung; Benjamin J Cowling Journal: Epidemiology Date: 2012-07 Impact factor: 4.822
Authors: Caroline van Gemert; Margaret Hellard; Emma S McBryde; James Fielding; Tim Spelman; Nasra Higgins; Rosemary Lester; Hassan Vally; Isabel Bergeri Journal: Emerg Infect Dis Date: 2011-09 Impact factor: 6.883
Authors: Aharona Glatman-Freedman; Ian Portelli; Susan K Jacobs; Justin I Mathew; Jonathan E Slutzman; Lewis R Goldfrank; Silas W Smith Journal: PLoS One Date: 2012-11-30 Impact factor: 3.240