What is 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. The best way to prevent
the flu is to get a
flu vaccine each fall.
Every year in the United States, on average:
Some people are at high risk for serious flu
complications, such as older people, young children, and
people with certain health conditions, including
Symptoms & Complications of Flu
Symptoms of flu include:
- fever (usually high),
- extreme tiredness,
- dry cough,
- sore throat,
- runny or stuffy nose, and
- muscle aches.
- Gastro-intestinal symptoms, such as nausea,
vomiting, and diarrhea, are much more common among
children than adults.
Some of the complications caused by
flu include bacterial pneumonia, dehydration, and
worsening of chronic medical conditions, such as
congestive heart failure, asthma, or diabetes. Children
may get sinus problems and ear infections.
How Flu Spreads
The flu spreads in respiratory droplets caused by
coughing and sneezing. It usually spreads from person to
person, though occasionally a person may become infected
by touching something with virus on it and then touching
their mouth or nose.
Adults may be able to infect others beginning 1 day
before getting symptoms and up to 7
days after getting sick. That
means that you can give someone the flu before you know
you’re sick as well as while you are sick.
Preventing the Flu
The single best way to prevent the flu is to get a
flu vaccine each fall. There also are certain good
health habits that can help prevent the flu (see
below). In addition, antiviral medications may be
used to prevent the flu. (For more information, see
Antiviral Drugs and the Flu.)
There are two types of vaccines:
- The "flu shot" -- an inactivated vaccine
(containing killed virus) that is given with a
needle. The flu shot is approved
for use in people older than 6 months, including
healthy people and people with chronic medical
- The nasal-spray flu vaccine -- a vaccine made
with live, weakened flu viruses that do not cause
the flu (sometimes called LAIV for “Live Attenuated
Influenza Vaccine”). LAIV is approved for use in
healthy people 5 years to 49 years of age who are
About two weeks after vaccination, antibodies that
provide protection against influenza virus infection
develop in the body.
When to Get Vaccinated
October or November is the best time to get
vaccinated, but you can still get vaccinated in December
and later. Flu season can begin as early as October and
last as late as May.
Who Should Get Vaccinated?
Because of a shortfall in flu shot production for
this season, CDC is recommending that certain people be
given priority for getting the flu shot. People in the
following groups should seek vaccination this season:
- all children aged 6–23 months;
- adults aged 65 years and older;
- persons aged 2–64 years with underlying chronic
- all women who will be pregnant during the
- residents of nursing homes and long-term care
- children aged 6 months–18 years on chronic
- health-care workers involved in direct patient
- out-of-home caregivers and household contacts of
children aged <6 months.
These are people who are at high risk for serious flu
complications or are in contact with people at high risk
for serious flu complications.
People who are not included in one of the priority
groups listed above are asked to forego or defer
vaccination because of the vaccine supply situation.
Who Should Not Be Vaccinated
There are some people who should not be vaccinated.
- People who have a severe allergy to chicken
- People who have had a severe reaction to an
influenza vaccination in the past.
- People who developed
Guillain-Barré syndrome (GBS) within 6 weeks of
getting an influenza vaccine previously.
- Children less than 6 months of age.
- People who are sick with a fever. (These people
can get vaccinated once their symptoms lessen.)
Other Good Health Habits
- Avoid close contact.
Avoid close contact with people who are sick. When
you are sick, keep your distance from others to
protect them from getting sick too.
- Stay home when you are sick.
If possible, stay home from work, school, and
errands when you are sick. You will help prevent
others from catching your illness.
- Cover your mouth and nose.
Cover your mouth and nose with a tissue when
coughing or sneezing. It may prevent those around
you from getting sick.
- Clean your hands.
Washing your hands often will help protect you from
- Avoid touching your eyes, nose or mouth.
Germs are often spread when a person touches
something that is contaminated with germs and then
touches his or her eyes, nose, or mouth.