Household Transmission of Pandemic (H1N1) 2009, UK | CDC EID

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Volume 17, Number 6–June 2011
Research
Use of Antiviral Drugs to Reduce Household Transmission of Pandemic (H1N1) 2009, United Kingdom1
Richard G. Pebody, Ross Harris, George Kafatos, Mary Chamberland, Colin Campbell, Jonathan S. Nguyen-Van-Tam, Estelle McLean, Nick Andrews, Peter J. White, Edward Wynne-Evans, Jon Green, Joanna Ellis, Tim Wreghitt, Sam Bracebridge, Chikwe Ihekweazu, Isabel Oliver, Gillian Smith, Colin Hawkins, Roland Salmon, Brian Smyth, Jim McMenamin, Maria Zambon, Nick Phin, and John M. Watson
Author affiliations: Health Protection Agency, London, UK (R.G. Pebody, R. Harris, G. Kafatos, M. Chamberland, C. Campbell, J.S. Nguyen-Van-Tam, E. McLean, N. Andrews, P.J. White, E. Wynne-Evans, J. Green, J. Ellis, T. Wreghitt, S. Bracebridge, C. Ihekweazu, I. Oliver, G. Smith, C. Hawkins, M. Zambon, N. Phin, J.M. Watson); Imperial College, London (P.J. White); Public Health Wales, Cardiff, Wales, UK (R. Salmon); Public Health Agency Northern Ireland, Belfast, Northern Ireland (B. Smyth); and Health Protection Scotland, Glasgow, Scotland (J. McMenamin)


Suggested citation for this article

Abstract
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%. Following emergence of pandemic influenza A (H1N1) 2009 in North America in spring 2009 (1,2), global spread of the virus was rapid (3,4). In the United Kingdom, the first confirmed cases were detected in travelers returning from Mexico (5). The United Kingdom implemented a containment strategy until July 2009 that involved rapid case ascertainment, early treatment with antiviral drugs (AVs), and postexposure prophylaxis of patients' close contacts.

One key uncertainty was the transmissibility of the virus in household settings. Household-based studies of avian influenza previously provided a measure of transmissibility of newly emerging influenza viruses and also of the effectiveness of AVs in reducing spread (6). Early reports on pandemic (H1N1) 2009 have provided information on household transmission (7–11). Although most are from settings where AVs were not used (8,10) or where only a limited number of households were recruited (7,9), early work suggests that AVs had some effect on spread (11,12).

A detailed investigation of the first few 100 (FF100) case-patients and their close contacts (13) was undertaken across the United Kingdom beginning in April 2009 to gain an early understanding of the clinical and epidemiologic parameters of pandemic (H1N1) 2009 (14). Following the publication of early FF100 findings (5,11,15), we report the final results from ≈300 UK households of key household transmission characteristics.

full-text:
Household Transmission of Pandemic (H1N1) 2009, UK | CDC EID


Suggested Citation for this Article
Pebody RG, Harris R, Kafatos G, Chamberland M, Campbell C, Nguyen-Van-Tam JS, et al. Use of antiviral drugs to reduce household transmission of pandemic (H1N1) 2009, United Kingdom. Emerg Infect Dis [serial on the Internet]. 2011 Jun [date cited]. http://www.cdc.gov/EID/content/17/6/990.htm

DOI: 10.3201/eid1706.101161



1Elements of this work were presented at the Health Protection Agency Annual Conference in 2009. An abstract was presented at the International Conference on Emerging Infectious Diseases, Atlanta, Georgia, USA, 2010.


Comments to the Authors
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Richard G. Pebody, Centre for Infections, 61 Colindale Ave, Health Protection Agency, London NW9 5EQ, UK; email: richard.pebody@hpa.org.uk