particular person may die from influenza is a million dollar question that we need to tackle. >> it is surprising how much we need to learn about flu a disease that causes world why epidemic every year. the flu test came back positive. okay, it is just a flu like it was no big deal. >> it spreads across the globe, hopizing three hospitalizing thr four millions. >> within 24 hours, she was incubated. >> killing at least 200,000 every year. >> we went in as they were coating her. the majority of the influenza, patients have something we call a risk factor. >> they have weak immune system