This report describes the preliminary results from the investigation of a large school outbreak of influenza A(H1N1)v in Birmingham, United Kingdom in May 2009, when influenza A(H1N1)v was confirmed ...in 64 of 175 (36%) symptomatic pupils and members of staff.
TOC Summary: Early treatment of primary case-patients and prophylaxis of household contacts provides effective protection.
The United Kingdom implemented a containment strategy for pandemic (H1N1) ...2009 through administering antiviral agents (AVs) to patients and their close contacts. This observational household cohort study describes the effect of AVs on household transmission. We followed 285 confirmed primary cases in 259 households with 761 contacts. At 2 weeks, the confirmed secondary attack rate (SAR) was 8.1% (62/761) and significantly higher in persons <16 years of age than in those >50 years of age (18.9% vs. 1.2%, p<0.001). Early (
<
48 hours) treatment of primary case-patients reduced SAR (4.5% vs. 10.6%, p = 0.003). The SAR in child contacts was 33.3% (10/30) when the primary contact was a woman and 2.9% (1/34) when the primary contact was a man (p = 0.010). Of 53 confirmed secondary case-patients, 45 had not received AV prophylaxis. The effectiveness of AV prophylaxis in preventing infection was 92%.
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