Seasonal Flu Shot
Questions & Answers
Visit 2012-2013 Season: What You Should Know for flu and flu vaccine information specific to the 2012-13 flu season.
What is the flu shot?
The flu shot is an inactivated vaccine (containing killed virus) that is given with a needle, usually in the arm. It contains three seasonal influenza viruses that are grown in eggs. The seasonal flu vaccine protects against three influenza viruses that research indicates will be most common during the upcoming season.
Is there more than one type of flu shot available?
Yes. There are three different flu shots available. In addition to the regular flu shot, there are other flu shots given with a needle, including a high-dose flu shot for people 65 and older and an intradermal flu shot for people 18 to 64 years of age.
- The regular seasonal flu shot is “intramuscular” which means it is injected into muscle (usually in the upper arm). It has been used for decades and is approved for use in people 6 months of age and older, including healthy people, people with chronic medical conditions and pregnant women. Regular flu shots make up the bulk of the vaccine supply produced for the United States.
- The high-dose vaccine is for people 65 and older which also is intramuscular.
- The intradermal vaccine is for people 18 to 64 years of age which is injected with a needle into the “dermis” or skin.
Who Should Get Vaccinated This Season?
Everyone who is at least 6 months of age should get a flu vaccine this season. It’s especially important for some people to get vaccinated. Those people include the following:
- People who are at high risk of developing serious complications like pneumonia if they get sick with the flu. This includes:
- People who have certain medical conditions including asthma, diabetes, and chronic lung disease.
- Pregnant women.
- People 65 years and older
- People who live with or care for others who are high risk of developing serious complications. This includes:
- household contacts and caregivers of people with certain medical conditions including asthma, diabetes, and chronic lung disease.
Use of the Nasal Spray Flu Vaccine
It should be noted that vaccination with the nasal-spray flu vaccine is always an option for healthy* persons aged 2 through 49 years who are not pregnant.
Who should not get a flu shot?
Talk with a doctor before getting a flu shot if you:
- Have ever had a severe allergic reaction to eggs
- Have ever had a serious reaction to a previous flu shot
- Have ever had Guillain-Barré Syndrome (a severe paralytic illness, also called GBS) that occurred after receiving influenza vaccine. Your doctor will help you decide whether the vaccine is recommended for you.
If you are sick with a fever when you go to get your flu shot, you should talk to your doctor or nurse about getting your shot at a later date. However, you can get a flu shot at the same time you have a respiratory illness without fever or if you have another mild illness.
How effective is the flu shot?
The ability of a flu vaccine to protect a person depends on the age and health status of the person getting the vaccine, and the similarity or “match” between the viruses or virus in the vaccine and those in circulation.
What are the risks from getting a flu shot?
The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot. The risk of a flu shot causing serious harm or death is extremely small. However, a vaccine, like any medicine, may rarely cause serious problems, such as severe allergic reactions. Almost all people who get influenza vaccine have no serious problems from it.
What are the side effects that could occur?
- Soreness, redness, or swelling where the shot was given
- Fever (low grade)
The intradermal flu shot may cause other additional mild side effects including:
- Toughness and itching where the shot was given
If these problems occur, they begin soon after the shot and usually last one to two days.
Can severe problems occur?
Life-threatening allergic reactions are very rare. Signs of serious allergic reaction can include breathing problems, hoarseness or wheezing, hives, paleness, weakness, a fast heartbeat, or dizziness. If they do occur, it is within a few minutes to a few hours after the shot. These reactions are more likely to occur among persons with a severe allergy to eggs, because the viruses used in the influenza vaccine are grown in hens’ eggs. People who have had a severe reaction to eggs or a flu shot in the past should not get a flu shot before seeing a physician.
Guillain-Barré syndrome: Normally, about one person per 100,000 people per year will develop Guillain-Barré syndrome (GBS), an illness characterized by fever, nerve damage, and muscle weakness. In 1976, vaccination with the swine flu vaccine was associated with getting GBS. Several studies have been done to evaluate if other flu vaccines since 1976 were associated with GBS. Only one of the studies showed an association. That study suggested that one person out of 1 million vaccinated persons may be at risk of GBS associated with the vaccine.
What should I do if I have had a serious reaction to seasonal influenza vaccine?
Call a doctor, or get to a doctor right away.
Tell your doctor what happened, the date and time it happened, and when you got the flu shot.
Ask your doctor, nurse, or health department to file a Vaccine Adverse Event Reporting System (VAERS) form, or call VAERS at 1-800-822-7967.
Can the flu shot give me the flu?
No, a flu shot cannot cause flu illness. The viruses contained in flu shots are inactivated (killed), which means they cannot cause infection. Flu vaccine manufacturers kill the viruses used in the flu shot during the process of making vaccine, and batches of flu vaccine are tested to make sure they are safe. In randomized, blinded studies, where some people got flu shots and others got saltwater shots, the only differences in symptoms was increased soreness in the arm and redness at the injection site among people who got the flu shot. There were no differences in terms of body aches, fever, cough, runny nose or sore throat.
More information about these studies is available at:
- Carolyn Bridges et al. (2000). Effectiveness and cost-benefit of influenza vaccination of healthy working adults: A randomized controlled trial .
- Kristin Nichol et al. (1995). The effectiveness of vaccination against influenza in healthy working adults. New England Journal of Medicine. 333(14): 889-893.
Why do some people not feel well after getting the flu shot?
The most common side effect of the flu vaccine in adults is soreness at the spot where the shot was given, which usually lasts less than two days. The soreness is often caused by a person’s immune system making protective antibodies to the killed viruses in the vaccine. These antibodies are what allow the body to fight against flu. The needle stick may also cause some soreness at the injection site. According to the Advisory Committee on Immunization Practices (ACIP), rare symptoms include fever, muscle pain, and feelings of discomfort or weakness. If these problems occur, they are very uncommon and usually begin soon after the shot and last 1-2 days.
What about people who get a seasonal flu vaccine and still get sick with flu-like symptoms?
There are several reasons why someone might get flu-like symptoms even after they have been vaccinated against the flu.
- People may be exposed to an influenza virus shortly before getting vaccinated or during the two-week period that it takes the body to gain protection after getting vaccinated. This exposure may result in a person becoming ill with flu before the vaccine begins to protect them.
- People may become ill from other (non-flu) viruses that circulate during the flu season, which can also cause flu-like symptoms (such as rhinovirus).
- A person may be exposed to an influenza virus that is not included in the seasonal flu vaccine. There are many different influenza viruses that circulate every year. The flu shot protects against the 3 viruses that research suggests will be most common.
- Unfortunately, some people can get infected with an influenza vaccine virus despite getting vaccinated. Protection provided by influenza vaccination can vary widely, based in part on health and age factors of the person getting vaccinated. In general, the flu vaccine works best among young healthy adults and older children. Some older people and people with certain chronic illnesses may develop less immunity after vaccination. However, even among people who tend to respond less well to vaccination, the flu vaccine can still help prevent influenza. Vaccination is particularly important for people at high risk of serious flu-related complications and for close contacts of high-risk people. For more information about the effectiveness of the flu vaccine, see How Well Does the Seasonal Flu Vaccine Work?
Flu Clinic Locations Open To The PublicVaccine Locator
*"Healthy" indicates persons who do not have an underlying medical condition that predisposes them to influenza.