Facts about Flu (Influenza)
Printable version (PDF - 8/25/10)
Flu and You: Important Information for Older Adults (PDF - 8/24/10)
Influenza is a viral infection of the nose, throat, bronchial tubes and lungs. There are two main types of virus: influenza A and influenza B. Each type includes many different strains, which tend to change each year.
When does influenza occur?
Influenza is most common during the fall and winter months. Flu activity often increases during the late fall and early winter in the United States, but peak levels generally occur between late December and early March. Illnesses resembling influenza may occur during the summer months but they are usually due to other viruses.
Who gets influenza?
Anyone can get influenza, but it is most serious in the elderly, in young children, in people with chronic underlying health conditions such as asthma, diabetes or a weakened immune system.
How is influenza spread?
Influenza is highly contagious and is easily transmitted through contact with droplets from the nose and throat of an infected person during coughing and sneezing.
What are the symptoms of influenza?
Typical symptoms include fever, chills, aches, cough and sore throat. Intestinal symptoms, such as vomiting or diarrhea, are possible but uncommon. Although most people are ill for only a few days, influenza sometimes leads to more serious illness, such as pneumonia. Influenza-related illness, including pneumonia, causes approximately 36,000 deaths in the United States each year. Here in New York City, influenza causes an estimated 1,100 deaths, and respiratory infections cause more than 2,000.
How soon after infection do symptoms appear?
Influenza generally occurs within 1 to 4 days after exposure.
How is influenza diagnosed?
Doctors diagnose influenza by checking for common symptoms such as fever, chills, aches, cough and sore throat. Lab tests are sometimes used to confirm the diagnosis, but these tests are not necessary or useful in most instances.
What should I do if you I get flu-like symptoms?
Most people recover from flu on their own, without medical treatment. They don’t need to go to the hospital, but they do need to take steps to avoid spreading the infection. If you have a fever (100 degrees or higher), plus a cough or sore throat, be sure to take these steps:
- Stay home from work or school. Don’t return until you have been free of fever for 24 hours.
- Avoid close contact with other people. Stay away from crowded public places and avoid close face-to-face contact with household members.
- Cover your nose and mouth when you cough or sneeze
- Wash your hands often.
When should I call a doctor?
Some people are more likely than others to get very sick with the flu. People belong to any of the following higher risk groups should call a health care provider if they have flu-like symptoms or have had recent close contact with someone with flu-like symptoms:
- Pregnant women
- Women who have given birth, or had a miscarriage or abortion in the past 2 weeks
- People younger than 2 or 65 and over
- People with any of these medical conditions:
|Health Conditions that Increase the Risk of Severe Influenza|
- Asthma or any other chronic respiratory diseases
Heart, kidney or liver disease
- Hematologic diseases, such as sickle cell anemia
Metabolic disorders, such as diabetes
- Weakened immune system, from illness or medication
- Neuromuscular disorders that interfere with breathing or the discharge of mucus
- Long-term aspirin therapy in people under 19
- Morbid obesity
What is the treatment for influenza?
Rest and liquids are usually adequate, but antiviral medication can help prevent severe illness and complications in people at high risk. Four antiviral drugs – amantadine, rimantidine, zanamivir and oseltamivir – are available by prescription.
When should I go to the hospital?
Go to the hospital or call 911 right away if you have trouble breathing or experience any of these other severe symptoms:
- Pain or pressure in the chest or stomach
- Dizziness or confusion
- Increasing fever or vomiting that won’t stop
- Can’t eat or drink
- Extreme irritability (in a child)
How can I protect myself from influenza?
Getting vaccinated is the best way to avoid influenza. Influenza vaccines (flu shots) are available from private health care providers, from Health Department immunization clinics, and from most pharmacies.
Does past infection with influenza make a person immune?
The viruses that cause influenza frequently change, so people who have been infected or immunized in previous years may become infected with a new strain. To maintain your immunity, you need to get a seasonal influenza vaccine every year.
Who should get vaccinated against seasonal influenza?
Everyone aged 6 months and older should get an influenza vaccine every year. Vaccination is especially important for certain groups of people who can become extremely sick if they catch influenza or are at high risk of passing the virus to other people:
- Pregnant women
- All health care workers
- Anyone 6 months through 59 months of age
- Anyone 19 through 49 years of age who has an underlying health condition that increases risk (see the box above)
- Adults 50 and older
- Anyone who lives with or cares for infants under 6 months of age
How can I help prevent the spread of influenza?
- Cover your nose and mouth with a tissue when you cough or sneeze, and dispose of the tissue afterward.
- If you don't have a tissue, cough or sneeze into your sleeve, using the bend in your arm to cover your nose and mouth.
- Clean your hands after you cough or sneeze, using soap and warm water, or an alcohol-based hand cleaner.
- If you get the flu, avoid exposing others. Stay home from work or school.
back to top