Influenza (the flu) is a common seasonal respiratory illness. The flu is caused by influenza viruses that infect the nose, throat, and sometimes the lungs.
There are two types of influenza viruses: type A and type B. Avian (bird) and swine flu are type A flu variants, although each type includes a variety of strains that can change from year to year. Type A viruses tend to mutate at a faster rate and can spread from animals to humans. Type B viruses tend to mutate more slowly, which can result in more mild symptoms - although both types can lead to complications, especially for people in high-risk groups.
Symptoms can vary widely and range from mild to severe.
Symptoms:
- Infection with an influenza virus may cause mild or severe illness, and at times can lead to death. Symptoms usually appear suddenly and can include:
- Fever* or feeling feverish/chills
- *Not everyone with the flu will have a fever
- Cough
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- Headaches
- Fatigue (tiredness)
- Vomiting and diarrhea are common in some people
Click here for signs and symptoms of flu.
Transmission:
Flu spreads from person to person through respiratory droplets released when an infected person coughs, sneezes, or talks. These respiratory droplets may land in the mouths or noses of people within six feet of the infected person or may be inhaled into the lungs. Flu viruses are transmitted through direct contact. A person with the flu can begin spreading it to others one day before they get sick and up to seven days after developing symptoms. Although certain people (infants and people who have a weakened immune system) will remain contagious for longer.
Click here for more information about how flu spreads.
Prevention:
The best way to prevent the flu is to get a flu shot every year. Vaccination against the flu lowers the risk of serious flu complications, including hospitalization and death. Everyday actions may also help prevent the flu, including:
- Avoid close contact with those who are sick
- Stay home if you are sick for at least 24 hours after your fever goes away without using fever reducing medicines.
- Cover your mouth and nose with a tissue when coughing or sneezing, then dispose of the tissue.
- Wash your hands with soap and water, scrubbing for at least 20 seconds. If soap and water are not available, use an alcohol-based hand sanitizer.
- Avoid touching your mouth, nose, or eyes.
- Frequently clean and sanitize high-touched surfaces like doorknobs, handrails, and light switches, especially if someone is sick.
Click here for more information about preventing seasonal flu.
What to do if you get sick:
Typically, people with the flu will experience a mild illness and not require medical care or antiviral medicine. If you are experiencing flu symptoms, generally, you should stay home and avoid contact with other people except to get medical care. However, if you experience emergency warning signs, seek medical care right away. Emergency warning signs can vary between children and adults. Learn more about the signs here.
The Center for Disease Control (CDC) recommends that people at higher risk for serious flu-related complications should get antiviral treatment as early as possible, because benefit is greatest if treatment is started within two (2) days after illness onset.
Click here for more information about what to do if you get sick with the flu.
High Risk Populations
- Although the flu can impact anyone, certain people have a higher risk of developing complications. These populations include:
- Adults 65 years and older
- Children younger than 2 years old1
- People with asthma or chronic lung disease (examples: chronic obstructive pulmonary disease [COPD] and cystic fibrosis)
- People with neurologic and neurodevelopment conditions
- People with blood disorders (such as sickle cell disease)
- People with endocrine disorders (such as diabetes mellitus)
- People with heart disease (such as congenital heart disease, congestive heart failure and coronary artery disease)
- People with kidney disorders
- People with liver disorders
- People with metabolic disorders (such as inherited metabolic disorders and mitochondrial disorders)
- People with a body mass index (BMI) of 40 kg/m2 or higher
- People younger than 19 years old on long-term aspirin- or salicylate-containing medications.
- People with a weakened immune system due to disease (such as people with HIV or AIDS, or some cancers such as leukemia) or medications (such as those receiving chemotherapy or radiation treatment for cancer, or persons with chronic conditions requiring chronic corticosteroids or other drugs that suppress the immune system)
- People who have had a stroke
- People with certain disabilities—especially those who may have trouble with muscle function, lung function, or difficulty coughing, swallowing, or clearing fluids from their airways.
For more information about people at increased risk for flu complications.
Treatment and Care
If you get sick, a doctor may prescribe antiviral medication. These medications work best when started in the first two days of becoming ill and can shorten the length of your illness, ease symptoms, and prevent flu complications. Contact your healthcare provider if you have flu symptoms and are at higher risk for severe flu illness, if you're feeling very ill, or if you are concerned about your health.
If you get sick:
- If your doctor prescribes antivirals, take them as directed.
- Monitor symptoms, rest, and drink plenty of fluids.
- Stay home and away from others to avoid spreading the illness unless you need medical attention.
- When you sneeze or cough, cover your mouth and nose with a tissue. After using the tissue, dispose of it in the trash.
- Use soap and water to frequently wash your hands. Use an alcohol-based hand rub in the absence of soap and water.
- Clean and disinfect surfaces and objects that may be contaminated.
Click here for a parent flu guide.