Influenza (''flu'') is a contagious disease that spreads around the United States every winter, usually between October and May.
Flu is caused by the influenza virus, and can be spread by coughing, sneezing, and close contact.
Anyone can get flu, but the risk of getting flu is highest among children. Symptoms come on suddenly and may last several days. They can include:
runny or stuffy nose
Flu can make some people much sicker than others. These people include young children, people 65 and older, pregnant women, and people with certain health conditions-such as heart, lung or kidney disease, or a weakened immune system. Flu vaccine is especially important for these people, and anyone in close contact with them.
Flu can also lead to pneumonia, and make existing medical conditions worse. It can cause diarrhea and seizures in children.
Each year thousands of people in the United States die from flu, and many more are hospitalized. Flu vaccine is the best protection we have from flu and its complications.
Flu vaccine also helps prevent spreading flu from person to person.
There are two types of influenza vaccine:
You are getting a live, attenuated influenza vaccine (called LAIV), which is sprayed into the nose. ''Attenuated'' means weakened. The viruses in the vaccine have been weakened so they can't make you sick.
A different vaccine, the ''flu shot,'' is an inactivated vaccine (not containing live virus). It is given by injection with a needle. This vaccine is described in a separate monograph, Influenza Vaccine, Inactivated.
Flu vaccine is recommended every year. Children 6 months through 8 years of age should get two doses the first year they get vaccinated.
Flu viruses are always changing. Each year's flu vaccine is made to protect from viruses that are most likely to cause disease that year. While flu vaccine cannot prevent all cases of flu, it is our best defense against the disease. LAIV protects against 4 different influenza viruses.
It takes about 2 weeks for protection to develop after the vaccination, and protection lasts several months to a year.
Some illnesses that are not caused by influenza virus are often mistaken for flu. Flu vaccine will not prevent these illnesses. It can only prevent influenza.
LAIV may be given to people 2 through 49 years of age, who are not pregnant. It may safely be given at the same time as other vaccines.
LAIV does not contain thimerosal or other preservatives.
Tell the person who gives you the vaccine:
If you have any severe (life-threatening) allergies, including an allergy to eggs. If you ever had a life-threatening allergic reaction after a dose of flu vaccine, or have a severe allergy to any part of this vaccine, you should not get a dose.
If you ever had Guillain-Barre Syndrome (a severe paralyzing illness, also called GBS). Some people with a history of GBS should not get this vaccine. This should be discussed with your doctor.
If you have gotten any other vaccines in the past 4 weeks, or if you are not feeling well. They might suggest waiting. But you should come back.
You should get the flu shot instead of the nasal spray if you:
have a weakened immune system
have certain long-term health problems
are a young child with asthma or wheezing problems
are a child or adolescent on long-term aspirin therapy
have close contact with someone who needs special care for an extremely weakened immune system
are younger than 2 or older than 49 years. (Children 6 months and older can get the flu shot. Children younger than 6 months can't get either vaccine.)
The person giving you the vaccine can give you more information.
With a vaccine, like any medicine, there is a chance of side effects. These are usually mild and go away on their own.
Serious side effects are also possible, but are very rare. LAIV is made from weakened virus and does not cause flu.
Mild problems that have been reported following LAIV:
Children and adolescents 2-17 years of age:
runny nose, nasal congestion or cough
headache and muscle aches
abdominal pain or occasional vomiting or diarrhea
Adults 18-49 years of age:
runny nose or nasal congestion
cough, chills, tiredness/weakness
Severe problems that could follow LAIV:
A severe allergic reaction could occur after any vaccine (estimated less than 1 in a million doses).
The safety of vaccines is always being monitored. For more information, visit: http://www.cdc.gov/vaccinesafety/ .
What should I look for?
Look for anything that concerns you, such as signs of a severe allergic reaction, very high fever, or behavior changes.
Signs of a severe allergic reaction can include hives, swelling of the face and throat, difficulty breathing, a fast heartbeat, dizziness, and weakness. These would start a few minutes to a few hours after the vaccination.
What should I do?
If you think it is a severe allergic reaction or other emergency that can't wait, call 9-1-1 or get the person to the nearest hospital. Otherwise, call your doctor.
Afterward, the reaction should be reported to the Vaccine Adverse Event Reporting System (VAERS). Your doctor might file this report, or you can do it yourself through the VAERS web site at
, or by calling
VAERS is only for reporting reactions. They do not give medical advice.
The National Vaccine Injury Compensation Program (VICP) is a federal program that was created to compensate people who may have been injured by certain vaccines.
Persons who believe they may have been injured by a vaccine can learn about the program and about filing a claim by calling
Ask your doctor.
Call your local or state health department
Contact the Centers for Disease Control and Prevention (CDC): call
Live Attenuated Influenza Vaccine Information Statement. U.S. Department of Health and Human Services/Centers for Disease Control and Prevention National Immunization Program. 7/26/13.
Last Revised - 08/15/2013
AHFS® Consumer Medication Information. © Copyright, 2014. The American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.