One person may have some symptoms and others may have different symptoms. They include fever, weakness, muscle aches, cough, sore throat and gastrointestinal upset. The flu can be a severe respiratory infection to the point of respiratory arrest. People do die. The CDC says there are 30,000 to 50,000 deaths per year related to the flu and 500,000 are hospitalized from the flu. The most famous instance of severe flu was in 1918 when millions were killed.