How does the flu spread?

Influenza – the flu -- is highly contagious and is usually spread by sneezing and coughing. In North America, the flu virus is at its most contagious in January and February. Once people start getting infected, the flu rapidly spreads and infects family, friends and colleagues at work. In particular, schools are known to be a breeding ground for the flu, primarily because of the close quarters that students find themselves in. According to one study, approximately one-third of families that have school-aged children will become infected annually.

The flu spreads by either direct or indirect contamination. Common examples of direct contamination are sneezing and coughing. Whenever you sneeze or cough, you expel tiny droplets into the air that can travel almost three feet (approximately one meter). If someone who has the flu sneezes or coughs and the infected droplets make contact with a healthy person’s mouth or nose, the flu can spread in this way. Indirect contamination is another way that influenza is spread. If you’re infected with the virus and you either cough or sneeze into your hand, the flu can be spread if you proceed to touch a doorknob that a healthy person touches after you. The flu virus doesn’t travel through the skin; rather, people who touch a contaminated doorknob will become infected when they put their own hand inside their mouth or nose.


It takes anywhere from one to four days to begin to feel sick after first being exposed to the flu. However, the flu is contagious before you begin to experience symptoms; generally, the virus can be spread a full day before you start to sneeze and sniffle. Once you’ve started to experience flu-like symptoms, you remain contagious for up to seven days. Children can remain contagious for even longer than seven days.