J Infect Dis. Household Transmission of 2009 Influenza A (H1N1) Virus after a School-Based Outbreak in New York City, April-May 2009.

[Giuseppe]

Household Transmission of 2009 Influenza A (H1N1) Virus after a School-Based Outbreak in New York City, April-May 2009. (J Infect Dis., abstract, edited)

13. J Infect Dis. 2010 Apr 1;201(7):984-92.

Household Transmission of 2009 Influenza A (H1N1) Virus after a School-Based Outbreak in New York City, April-May 2009.

France AM, Jackson M, Schrag S, Lynch M, Zimmerman C, Biggerstaff M, Hadler J. - Epidemic Intelligence Service, Office of Workforce and Career Development, and 2National Center For Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; and 3New York City Department of Health and Mental Hygiene, New York, New York.

In April 2009, an outbreak due to infection with the 2009 pandemic influenza A (H1N1) virus (pH1N1) was investigated in a New York City high school. We surveyed household contacts of ill students to characterize the extent of transmission within households, identify contact groups at highest risk for illness, and assess the potential for preventing household transmission. Influenza-like illness (ILI) was reported by 79 of 702 household contacts (11.3% attack rate). Multivariate analysis showed that older age was protective: for each increasing year of age, the risk of ILI was reduced 5%. Additional protective factors included antiviral prophylaxis and having had a household discussion about influenza. Providing care for the index case patient and watching television with the index case patient were risk factors among parents and siblings, respectively. Fifty percent of cases occurred within 3 days of onset of illness in the student. These factors have implications for mitigating the impact of pH1N1 transmission.

PMID: 20187740 [PubMed - in process]
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[tetano]

Re: J Infect Dis. Household Transmission of 2009 Influenza A (H1N1) Virus after a School-Based Outbreak in New York City, April-May 2009.

Having a household discussion about how to prevent transmission was associated with a 40 percent reduction in risk for influenza among others in the household. Providing care for the sick student increased the risk among parents, the researchers found, while watching television and playing video games with the student was a risk factor for siblings.

The finding that a household discussion had a protective effect is especially relevant, given that a vaccine might not be available early in a pandemic. "This is important because it indicates that behavioral changes can be effective in decreasing the risk for secondary illness within a household," Dr. France said. "Understanding the risk and prevention factors that determine household transmission is very important to containing influenza, particularly if the strain of influenza is severe, and it is determined that attempting to contain it is critical to the national management of a pandemic."
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In an accompanying editorial, Ruth Lynfield, MD, of the Minnesota Department of Health, agreed and observed that the findings "are useful in reinforcing public health recommendations for infection control within households of infected individuals." When early action is most important at the beginning of a pandemic, Dr. Lynfield wrote, implementation is best reinforced by "data that support simple interventions in the household that are important for infection prevention."

The study also found a protective effect associated with preventive antiviral treatment, or prophylaxis. But the authors and the accompanying editorial highlight reports of the development of antiviral resistance and the need to reserve these drugs for influenza patients most at risk for developing complications, in line with recommendations from the Centers for Disease Control and Prevention (CDC).

http://www.news-medical.net/news/20...it-the-spread-of-H1N1-in-household-Study.aspx