Influenza (''flu'') is a contagious disease
It is caused by the influenza virus, which can be spread by coughing, sneezing, or nasal secretions.
Anyone can get influenza, but rates of infection are highest among children. For most people, symptoms last only a few days. They include:
runny or stuffy nose
Other illnesses can have the same symptoms and are often mistaken for influenza.
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, can get much sicker. Flu can cause high fever and pneumonia, and make existing medical conditions worse. It can cause diarrhea and seizures in children. Each year thousands of people die from influenza and even more require hospitalization.
By getting flu vaccine you can protect yourself from influenza and may also avoid spreading influenza to others.
There are two types of influenza vaccine:
Inactivated (killed) vaccine, the ''flu shot,'' is given by injection with a needle.
Live, attenuated (weakened) influenza vaccine is sprayed into the nostrils. This vaccine is described in a separate monograph.
A ''high-dose'' inactivated influenza vaccine is available for people 65 years of age and older. Ask your doctor for more information.
Influenza viruses are always changing, so annual vaccination is recommended. Each year scientists try to match the viruses in the vaccine to those most likely to cause flu that year. Flu vaccine will not prevent disease from other viruses, including flu viruses not contained in the vaccine.
It takes up to 2 weeks for protection to develop after the shot. Protection lasts about a year.
Some inactivated influenza vaccine contains a preservative called thimerosal. Thimerosal-free influenza vaccine is available. Ask your doctor for more information.
All people 6 months of age and older should get flu vaccine.
Vaccination is especially important for people at higher risk of severe influenza and their close contacts, including healthcare personnel and close contacts of children younger than 6 months.
When should I get influenza vaccine?
Get the vaccine as soon as it is available. This should provide protection if the flu season comes early. You can get the vaccine as long as illness is occurring in your community.
Influenza can occur at any time, but most influenza occurs from October through May. In recent seasons, most infections have occurred in January and February. Getting vaccinated in December, or even later, will still be beneficial in most years.
Adults and older children need one dose of influenza vaccine each year. But some children younger than 9 years of age need two doses to be protected. Ask your doctor.
Influenza vaccine may be given at the same time as other vaccines, including pneumococcal vaccine.
Tell your doctor if you have any severe (life-threatening) allergies, including a severe allergy to eggs. A severe allergy to any vaccine component may be a reason not to get the vaccine. Allergic reactions to influenza vaccine are rare.
Tell your doctor if you ever had a severe reaction after a dose of influenza vaccine.
Tell your doctor if you ever had Guillain-Barré Syndrome (a severe paralytic illness, also called GBS). Your doctor will help you decide whether the vaccine is recommended for you.
People who are moderately or severely ill should usually wait until they recover before getting flu vaccine. If you are ill, talk to your doctor about whether to reschedule the vaccination. People with a mild illness can usually get the vaccine.
A vaccine, like any medicine, could possibly cause serious problems, such as severe allergic reactions. The risk of a vaccine causing serious harm, or death, is extremely small.
Serious problems from inactivated influenza vaccine are very rare. The viruses in inactivated influenza vaccine have been killed, so you cannot get influenza from the vaccine.
soreness, redness, or swelling where the shot was given
hoarseness; sore, red or itchy eyes; cough
If these problems occur, they usually begin soon after the shot and last 1–2 days.
Young children who get inactivated flu vaccine and pneumococcal vaccine (PCV13) at the same time appear to be at increased risk for seizures caused by fever. Ask your doctor for more information.
Tell your doctor if a child who is getting flu vaccine has ever had a seizure.
Life-threatening allergic reactions from vaccines are very rare. If they do occur, it is usually within a few minutes to a few hours after the shot.
In 1976, a type of inactivated influenza (swine flu) vaccine was associated with Guillain-Barré Syndrome (GBS). Since then, flu vaccines have not been clearly linked to GBS. However, if there is a risk of GBS from current flu vaccines, it would be no more than 1 or 2 cases per million people vaccinated. This is much lower than the risk of severe influenza, which can be prevented by vaccination.
One brand of inactivated flu vaccine, called Afluria, should not be given to children 8 years of age or younger, except in special circumstances. A related vaccine was associated with fevers and fever-related seizures in young children in Australia. Your doctor can give you more information.
The safety of vaccines is always being monitored. For more information, visit: http://www.cdc.gov/vaccinesafety/Vaccine_Monitoring/Index.html and http://www.cdc.gov/vaccinesafety/Activities/Activities_Index.html
What should I look for?
Any unusual condition, such as a high fever or unusual behavior. Signs of a serious allergic reaction can include difficulty breathing, hoarseness or wheezing, hives, paleness, weakness, a fast heart beat or dizziness.
What should I do?
Call a doctor, or get the person to a doctor right away.
Tell the doctor what happened, the date and time it happened, and when the vaccination was given.
Ask your doctor, nurse, or health department to report the reaction by filing a Vaccine Adverse Event Reporting System (VAERS) form. Or you can file this report through the VAERS web site at http://www.vaers.hhs.gov, or by calling
VAERS does not provide medical advice.
The National Vaccine Injury Compensation Program:
The National Vaccine Injury Compensation Program (VICP) was created in 1986.
People 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. They can give you the vaccine package insert or suggest other sources of information.
Call your local or state health department.
Contact the Centers for Disease Control and Prevention (CDC): call
Inactivated Influenza Vaccine Information Statement. U.S. Department of Health and Human Services/Centers for Disease Control and Prevention National Immunization Program. 7/2/12. 42 U.S.C. section 300aa-26
Last Revised - 10/15/2012
AHFS® Consumer Medication Information. © Copyright, 2013. 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.