How Does the Flu Spread?

How does the flu really spread?. Simon Potter/Cultura/Getty Images

During the cold winter months, the flu (influenza) spreads rapidly. We know that it is highly contagious and can be spread before you even have symptoms. But do you know how it is spread? Do you know how the flu is passed from person to person so easily?

Contrary to popular belief, it's not due to cold weather. Although the cold dry air may mean the virus moves and infects people more easily, it does not actually cause the illness.

It's also not really spread through the air the way many people think it is.

Droplet Transmission

Influenza is spread through droplets, which means if you cough, sneeze or get any droplet matter from your respiratory system onto anything, it can be spread to someone else. This can happen in two ways.

First, if you sneeze, cough or talk, microscopic droplets are released into the air as far as six feet away from you. Anyone around you can breathe in those droplets that contain the influenza virus.

Another possibility is that those droplets you sneezed, coughed or breathed out land on objects and the next person that touches that object and then touches their eyes, mouth or nose can be infected.

Spreading the Virus

If that person's immune system isn't able to kill off the virus, they will develop symptoms within 1 to 4 days of being infected. They are also now spreading the virus themselves - even before symptoms start.

If you have the flu, you can spread it up to one day before your symptoms develop and 5 to 7 days after you get sick. Children who have the flu can spread the virus for longer than 7 days.

Protecting Yourself and Others

Most people know they should stay home when they are sick with something like the flu (although many people don't).

But it's pretty difficult to avoid passing the virus if you don't even know you have it yet.

This is one of the reasons flu vaccines are so important. If you are vaccinated against the flu, your body will have a chance to fight it off before it spreads in your body and you are less likely to pass it on to other people or get sick yourself.

If you do get sick, stay home! Know when to call in sick to work, wash your hands frequently and make sure those that come into contact with you do the same. Cover your cough and do everything you can to avoid being around people that fall into a high risk category for flu.

Preventing the spread of the flu virus is up to all of us. Even if you think it won't be serious for you if you get it, it might be for someone you pass it to.


How Flu Spreads. Seasonal Influenza (Flu) 12 Sep 13. US Centers for Disease Control and Prevention. Department of Health and Human Services. 18 Feb 14.

Continue Reading