- Doctor says her medical group has seen more patients than expected
- Shannon Zwanziger, 17, seemed perfectly healthy, got the flu and died within a week
- CDC officially declares a flu epidemic and says 15 children have died
(CNN)Shannon Zwanziger seemed perfectly healthy. She was an active 17-year-old who rarely got sick and hadn't been to a doctor in more than three years.
Go to CNN.com/unseenenemy for more stories and resources about epidemics, pandemics and the CNN Films documentary, "Unseen Enemy."