October 2026
During cold and flu season, you may wonder how the flu spreads and what you can do to lower your risk of getting sick. Here are answers to six common questions about how the flu is transmitted, how long someone may be contagious, and practical steps you can take to help protect yourself and your family.
1. How is the flu transmitted from a sick person to a healthy person?
Flu viruses spread primarily through respiratory droplets and aerosols produced when infected people cough, sneeze, or talk. People nearby can then catch the flu if the droplets land in their mouths or noses, if they touch a surface that has infectious droplets on it and then touch their face, or (less commonly) if they inhale infectious aerosols.
2. Can you catch the flu if you’re not around someone who is sick?
Yes, you can. It may seem surprising, but you don’t need to be in the same place at the same time as an infected person to catch the flu. Let’s say someone with the flu was in a room but left before you arrived. You won’t end up with droplets on your mouth or nose because they are heavy and settle quickly. But the virus in those droplets can remain infectious for at least four hours after landing on a hard surface. While person-to-person spread is the most common way the flu spreads, it is also possible to become infected after touching a contaminated surface and then touching your eyes, nose, or mouth.
3. Can you catch the flu from someone who doesn’t seem sick?
Unfortunately, yes. Most healthy adults can infect others starting one day before symptoms appear — and they remain contagious for several days afterward.
4. How long is someone contagious with the flu?
Most people remain contagious for about five to seven days after becoming sick. Children and those with compromised immune systems may pass the virus for longer than seven days.
5. Can you get the flu from the flu shot?
No, you cannot get the flu from a flu shot. The flu shot is made from an inactivated virus that can’t transmit infection. Some people become sick shortly after receiving a flu vaccine because they were exposed to a virus before the vaccine had time to provide protection, or because they became ill from another respiratory virus. It takes a week or two to get protection from the vaccine. But people often assume that because they got sick after getting the vaccine, the shot caused their illness.
Unlike the flu shot, the nasal spray flu vaccine uses a live attenuated (weakened) flu virus that can replicate only in the cooler temperatures of the nasal passages; it cannot survive in the warmer body. Healthy people are not at risk of catching the flu from the nasal spray vaccine though they may get mild, temporary nasal symptoms — like congestion or a runny nose — one or two days after receiving the spray.
6. How can you reduce your chances of catching the flu?
Get your annual flu shot. People who get the flu shot are less likely to get sick with the flu, less likely to need medical care if they do get the flu, less likely to be hospitalized, and more likely to survive if they do get sick.
Wash your hands often and make sure any children in your house do the same. Wash your hands often with soap and water for at least 20 seconds and encourage children to do the same. If soap and water are not available, use an alcohol-based hand sanitizer.
Stay away from sick people. The CDC recommends avoiding sick people and staying home if you’re sick.
Regularly disinfect high-touch surfaces. This includes at home and at work. High-touch surfaces include smartphones, faucets, doorknobs, handles of any type (toilet, refrigerator, etc.), light switches, remote controls, and computer keyboards.
Practice good hygiene if someone in your household has the flu. Linens, eating utensils, and dishes belonging to those who are sick should not be shared without washing thoroughly first.
Use a humidifier when the weather is cold and dry. If the humidity drops below 40%, it’s a lot easier for germs to survive in the air. Aim to keep the humidity inside your home between 40% and 60%. (but not higher— too humid and you risk fostering mold growth.)
