Simple, common sense behaviors, including having a discussion at home about how to prevent influenza, can help limit the spread of H1N1 in a household, according to a study of the initial outbreak in New York City in 2009. Published in the April 1 issue of the Journal of Infectious Diseases, the study is available online.
People with influenza symptoms are often told to stay home from work or school, which is why scientists need to understand how household transmission works and how to control it, not only in responding to H1N1 but also in preparing for future pandemics.
Anne Marie France, PhD, MPH, and her colleagues at the New York City Department of Health and Mental Hygiene and the Centers for Disease Control and Prevention (CDC) surveyed household members of ill students from the New York City high school where the H1N1 outbreak was first documented in April 2009. Because H1N1 was not yet established in the community, secondary cases of influenza-like illness were most likely acquired at home. One-third of the school's students were sick with influenza and told to stay home, and 322 households representing 702 household contacts responded to the survey. Seventy-nine contacts reported influenza-like illness, representing an 11.3 percent secondary attack rate (SAR), with half of the cases occurring within three days and 87 percent within seven days after the initial student reported symptoms.
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," 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."
