09/15/26 Public Health Education Topic: Influenza
Per CDC
Key points
Flu is a contagious respiratory illness caused by influenza viruses
Flu can cause mild to severe illness. Some people are at higher risk for more serious flu illness.
Most experts believe that influenza viruses spread mainly by droplets made when people with flu cough, sneeze, or talk
Getting a flu vaccine has been shown to reduce the risk of flu and serious flu complications.
Symptoms
Flu can cause mild to severe illness, and at times can lead to death. Flu symptoms usually come on suddenly. People who have flu often feel some or all of these signs and symptoms:
fever* or feeling feverish/chills
cough
sore throat
runny or stuffy nose
muscle or body aches
headaches
fatigue (tiredness)
some people may have vomiting and diarrhea, though this is more common in children than adults.
*It's important to note that not everyone with flu will have a fever.
Not everyone with flu has symptoms
Period of Contagiousness
You may be able to spread flu to someone else before you know you are sick, as well as when you have symptoms.
Studies have shown:
People with flu are most contagious during the first three days of their illness.
Some otherwise healthy adults may be able to infect others beginning one day before symptoms develop and five to seven days after becoming sick.
Some people, including young children and people with weakened immune systems, may be contagious for longer periods of time.
Onset of Symptoms
The time from when a person is exposed and infected with influenza virus to when symptoms begin is about two days but can range from about one to four days.
To learn more please visit: About Influenza | Influenza (Flu) | CDC
