Influenza (Flu) Fact Sheet
Last Reviewed: September 2012
What Everyone Should Know About Flu and the Flu Vaccine
What is the flu?
The flu is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. Some people, such as older people, young children, and people with certain health conditions, are at high risk for serious flu complications.
Every year in the United States:
- ~ 5% to 20% of the population gets the flu;
- on average more than 200,000 people are hospitalized from flu complications, and;
- over 23,600 people die from flu (with a range of 3,349-48,614 people); about 90% of such deaths occur in persons aged 65 years and older.
The best way to prevent this illness is by getting a flu vaccination.
What are the symptoms of the flu?
The flu usually starts suddenly and may include these symptoms:
- Fever* or feeling feverish/chills
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- 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.
Are some people at higher risk for complications than others from getting the flu?
Yes. People at higher risk for serious flu complications include older people, young children, and people of any age with certain health conditions.
What are the complications associated with the flu?
Some of the complications caused by flu include pneumonia, dehydration, and worsening of chronic medical conditions, such as heart or lung disease, asthma or diabetes. Children may get sinus problems and ear infections.
How is the flu spread?
The flu is spread in droplets released by coughing and sneezing. It usually spreads from person to person, though occasionally people may be infected by touching something with virus on it and then touching their mouth or nose.
When and for how long is a person able to spread the flu?
People with flu are contagious (able to infect others) beginning one day before getting symptoms. Adults remain contagious up to seven days after getting sick and children can remain contagious for even longer. That means that you can give someone the flu before you know you're sick as well as when you are sick.
Cold Versus Flu
What is the difference between a cold and the flu?
The flu and the common cold are both respiratory illnesses but they are caused by different viruses. Because colds and flu share many symptoms, it can be difficult (or even impossible) to tell the difference between them based on symptoms alone. Most people who have flu symptoms will not be tested, and do not need to be tested, because test results usually do not change how a patient is treated. Treatment, if decided upon by the health care provider, will usually be based on severity of symptoms and how likely a person is to have complications of flu – not on the basis of a test result.
What are the symptoms of the flu versus the symptoms of a cold?
In general, the flu is worse than the common cold, and symptoms such as fever, body aches, extreme tiredness and dry cough are more common and intense. Colds tend to develop gradually, while the flu tends to start very suddenly. Colds are usually milder than the flu. People with colds are more likely to have a runny or stuffy nose. Colds generally do not result in serious health problems, such as pneumonia, bacterial infections, or hospitalizations.
Preventing the Flu
What can I do to protect myself against the flu?
The single best way to prevent the flu is to get a flu vaccination each fall. There are two types of vaccines:
- The "flu shot" is an inactivated vaccine (containing killed virus) that is given with a needle. It can be given in the muscle or just under the skin. The flu shot that is given in the muscle is approved for use in people older than 6 months, including healthy people and people with chronic medical conditions. The flu shot that is given below the skin is for those 18-64 years of age.
- The nasal-spray flu vaccine is a vaccine (sometimes called LAIV for "Live Attenuated Influenza Vaccine") made with live, weakened flu viruses that do not cause the flu. LAIV is approved for use in healthy people 2 years to 49 years of age who are not pregnant.
Talk to your provider to find out which vaccine is right for you and your family.
About two weeks after vaccination, antibodies develop that protect against influenza virus infection for the entire year. Flu vaccines will not protect against illnesses caused by other viruses, such as the common cold.
Who should get the flu vaccine?
Everyone 6 months of age and older should get vaccinated against the flu. Vaccination should begin as soon as the vaccine is available.
Those people at greatest risk for complications of the flu and those most likely to get or spread the flu should be vaccinated with the flu vaccine as soon as it is available. The list below includes the groups of people more likely to get flu-related complications if they get sick from influenza:
People at High Risk for Developing Flu-Related Complications
- Children younger than 5, but especially children younger than 2 years old
- Adults 65 years of age and older
- Pregnant women
- Also, American Indians and Alaskan Natives seem to be at higher risk of flu complications
People who have medical conditions including:
- Neurological and neurodevelopmental conditions [including disorders of the brain, spinal cord, peripheral nerve, and muscle such as cerebral palsy, epilepsy (seizure disorders), stroke, intellectual disability (mental retardation), moderate to severe developmental delay, muscular dystrophy, or spinal cord injury].
- Chronic lung disease (such as chronic obstructive pulmonary disease [COPD] and cystic fibrosis)
- Heart disease (such as congenital heart disease, congestive heart failure and coronary artery disease)
- Blood disorders (such as sickle cell disease)
- Endocrine disorders (such as diabetes mellitus)
- Kidney disorders
- Liver disorders
- Metabolic disorders (such as inherited metabolic disorders and mitochondrial disorders)
- Weakened immune system due to disease or medication (such as people with HIV or AIDS, or cancer, or those on chronic steroids)
- People younger than 19 years of age who are receiving long-term aspirin therapy
- People who are morbidly obese (Body Mass Index, or BMI, of 40 or greater)
Does my child need to receive more than one dose of flu vaccine this season?
Some children aged 6 months through 8 years require two doses of influenza vaccine (given a minimum of four weeks apart). Children in this age group who are getting vaccinated for the first time will need two doses. If this is not the first season that your child is receiving flu vaccine, talk with your child's provider to determine how many doses your child needs to protect them from the flu this year.
Who should NOT be vaccinated?
There are some people who should not be vaccinated. They include:
- People who have had a severe reaction to an influenza vaccination in the past;
- People who developed Guillain-Barré syndrome (GBS) within six weeks of getting an influenza vaccine previously;
- Children less than 6 months of age.
Some people should wait to get vaccinated until they talk with their provider. They include:
- People who have a severe allergy to chicken eggs;
- People who are sick with a fever. (These people can get vaccinated once their symptoms lessen. People with a mild illness can usually get the vaccine.)
Can the flu be treated?
Yes. There are influenza antiviral drugs that can be used to treat flu illness. While NYSDOH recommends influenza vaccination as the first and most important step in preventing flu, antiviral drugs are a second line of defense against the flu. Antiviral drugs are not sold over-the-counter and are different from antibiotics. You can only get them if you have a prescription from your doctor or health care provider. Your health care provider can help decide whether you should take an antiviral drug and, if so, which one you should take.