These symptoms can range from very mild to very severe. Most people get better within a week or so but the flu can sometimes lead to pneumonia, which can be fatal. The flu most often occurs during winter months. Other viruses usually cause a Flu-like illness that happens in the summer. The viruses that cause Flu live in the nose and throat and are sprayed into the air when an infected person sneezes, coughs or talks.
People nearby can then inhale the virus.
Flu symptoms usually start one to three days after a person inhales the virus and up to a week later. The Flu can be very dangerous. Most people are only sick for a few days. However, the flu can be serious in the elderly and in people with chronic medical problems or weakened immune systems. Some people may develop dangerous complications such as pneumonia.