http://www.pandemicflu.gov/health/whatyoucando.html
U.S. Department of Health and Human Services
An influenza pandemic occurs when a new influenza A virus emerges for which there is little or no immunity in the human population, begins to cause serious illness and then spreads easily person-to-person worldwide. A pandemic is likely to be a prolonged and widespread outbreak that could require temporary changes in many areas of society, such as schools, work, transportation and other public services. This fact sheet discusses actions that communities, businesses, and individuals can take to decrease their risk during a pandemic, including adopting business/school practices that encourage sick employees/students to stay home.