An influenza vaccine protects you against the flu. A new form of the flu vaccine needs to be made most years to protect you against the exact strains that are expected to be most common.
Vaccine - influenza; Immunization - influenza; Flu shot; Flu vaccine
The flu is a contagious respiratory disease caused by an influenza virus. Thousands of people in the U.S. die each year from the flu or its complications. Most of those who die are the elderly, young children, or people with weakened immune system.
The flu vaccine that will be given this fall and winter will also protect you against H1N1 (swine) flu. You do not need a separate vaccine.
There are two types of flu vaccines: a flu shot and a nasal spray.
- The flu shot contains killed (inactive) viruses, so you cannot get the flu from this type of vaccine. However, some people do get a low-grade fever for a day or two after the shot. The flu shot is approved for people age 6 months and older.
- There is also a high-dose version of the flu shot approved for people 65 and older. However, it is not known if the higher dose vaccine is better at protecting from the flu.
- A nasal spray flu vaccine called FluMist uses a live, weakened virus instead of a dead one. It is approved for healthy people aged 2 to 49 who are not pregnant. It should not be used in those who have asthma or children under age 5 who have repeated wheezing episodes.
Flu vaccines are generally given at the beginning of the "flu season" -- usually around October in the U.S. However, they may be given as late as March, and still provide some benefit.
People traveling to other countries should be aware that the flu may occur at different times of the year from the U.S.
WHO SHOULD GET THE VACCINE
The Centers for Disease Control and Prevention (CDC) recommend that everyone 6 months and older should receive the flu vaccine. Some people are more likely to get the flu or to have a severe infection if they catch it. People at risk for more serious flu infections should always get a flu vaccine every year. The CDC recommends extra efforts to vaccinate the following people:
- Pregnant women or women who will be pregnant during the flu season
- Children younger than 5 years and especially those under 2 years (but 6 months or older)
- Household contacts and caregivers of children under the age of 6 months, including breastfeeding women
- Health care workers or those who live with a health care worker
- People who have chronic lung or heart disease
- People who have sickle cell anemia or other hemoglobinopathies
- People who live in a nursing home or extended care facilities
- People who live with someone who has chronic health problem
- People who have kidney disease, anemia, severe asthma, diabetes, or chronic liver disease
- People who have a weakened immune system (including those with cancer or HIV/AIDS)
- People who take long-term treatment with steroids for any condition
Older children and adults only need a single flu shot each year. However, children under age 9 should get two shots 1 month apart unless they have received two vaccinations for seasonal influenza since July 1, 2010. Be sure to ask your child’s doctor for more specific information.
Most people are protected from the flu about 2 weeks after receiving the vaccine.
RISKS AND SIDE EFFECTS
Most people have no side effects from the flu shot. Soreness at the injection site or minor aches and low grade fever may be present for several days.
As is the case with any drug or vaccine, there is a rare possibility of allergic reaction.
The regular seasonal flu shot has been shown to be safe for pregnant women and their babies.
Normal side effects of the nasal spray flu vaccine include fever, headache, runny nose, vomiting, and some wheezing. Although these symptoms sound like symptoms of the flu, the side effects do not become a severe or life-threatening flu infection.
WHO SHOULD NOT RECEIVE A FLU VACCINE
Some people should not be vaccinated without first talking to their doctor. The vaccine is not approved for people under 6 months of age. In general, you should not get a flu shot if you:
- Had a severe allergic reaction to chickens or egg protein (most people with a mild egg allergy can receive the flu shot safely)
- Have a fever or illness that is more than "just a cold"
- Had a moderate to severe reaction after a previous flu vaccine
- Developed Guillain-Barre syndrome within 6 weeks after receiving a flu vaccine
If you meet any of the above criteria, ask your doctor if a flu vaccine is safe for you.
Centers for Disease Control and Prevention (CDC). Prevention and Control ofI nfluenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2012. MMWR. 2012 Aug 17;61(32):613-618.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.
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