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Low secondary transmission of 2009 pandemic influenza A (H1N1) in households following an outbreak at a summer camp: relationship to timing of exposure

  • T. J. DOYLE (a1) (a2) and R. S. HOPKINS (a3)

Following an outbreak of 2009 pandemic influenza A (H1N1) at a residential summer camp for boys aged 10–16 years, we assessed secondary household transmission of the novel virus after their return home. Of 212 study participants who attended camp, 49 had confirmed or probable influenza for a primary attack rate of 23%. Of 87 exposed household contacts who did not attend camp, only three instances of probable transmission were observed, for a household secondary attack rate of 3·5%. All secondary cases occurred in households where the ill camp attendee returned home 1 day after onset of illness, with an attack rate of 14·3% in household contacts in this category. Returning home after peak infectivity to others and advanced warning prior to reintegration of sick individuals into the household probably contributed to the overall low secondary attack rate observed.

Corresponding author
*Author for correspondence: Mr T. J. Doyle, 4052 Bald Cypress Way, Bin A-12, Tallahassee, FL 32399-1720, USA. (Email:
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1.Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team. Emergence of a novel swine-origin influenza A (H1N1) virus in humans. New England Journal of Medicine 2009; 360: 26052615.
2.Odaira F, et al. Assessment of secondary attack rate and effectiveness of antiviral prophylaxis among household contacts in an influenza A(H1N1)v outbreak in Kobe, Japan, May–June 2009. Eurosurveillance 2009; 14 (35).
3.Fox JP, et al. Influenzavirus infections in Seattle families, 1975–1979. I. Study design, methods and the occurrence of infections by time and age. American Journal of Epidemiology 1982; 116: 212227.
4.Fox JP, et al. Influenza virus infections in Seattle families, 1975–1979. II. Pattern of infection in invaded households and relation of age and prior antibody to occurrence of infection and related illness. American Journal of Epidemiology 1982; 116: 228242.
5.Jennings LC, MacDiarmid RD, Miles JA. A study of acute respiratory disease in the community of Port Chalmers. I. Illnesses within a group of selected families and the relative incidence of respiratory pathogens in the whole community. Journal of Hygiene (London) 1978; 81: 4966.
6.Taber LH, et al. Infection with influenza A/Victoria virus in Houston families, 1976. Journal of Hygiene (London) 1981; 86: 303313.
7.Thacker SB. The persistence of influenza A in human populations. Epidemiologic Reviews 1986; 8: 129142.
8.Witkop CT, et al. Novel influenza A (H1N1) outbreak at the U.S. Air Force Academy: epidemiology and viral shedding duration. American Journal of Preventive Medicine 2010; 38: 121126.
9.Cowling BJ, et al. Preliminary findings of a randomized trial of non-pharmaceutical interventions to prevent influenza transmission in households. PLoS One 2008; 3: e2101.
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Epidemiology & Infection
  • ISSN: 0950-2688
  • EISSN: 1469-4409
  • URL: /core/journals/epidemiology-and-infection
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