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Flu shot: Your best bet for avoiding influenza
Getting a flu shot often protects you from coming down with the flu. And while the flu shot doesn't always provide total protection, it's still worth getting.
By Mayo Clinic staffThe Food and Drug Administration (FDA) has approved vaccines for the 2008-2009 flu season. The flu shot vaccines are designed to protect against strains of flu virus expected to be in circulation this fall and winter. Six manufacturers have begun shipping vaccine for this year's flu season.
Influenza is a viral infection that sickens millions of people each year and can cause serious complications, especially in children and older adults. Fortunately, the flu vaccine — available in the form of a flu shot or a nasal spray — offers protection against the flu.
Here are the answers to common questions about flu shots.
When is the flu vaccine available?
The flu vaccine is generally offered between September and mid-November, which is typically before the late-fall to early winter start of flu season. However, getting a flu shot even later in the flu season may still protect you. It takes up to two weeks to build immunity following a flu shot.
What kind of protection does the flu vaccine offer?
According to the Centers for Disease Control and Prevention (CDC), when the match between flu vaccine and circulating strains of flu virus is close, a flu shot is between 70 and 90 percent effective in warding off illness in healthy people under age 65. For older adults who don't live in nursing homes and for people with chronic medical conditions, the flu vaccine is 30 to 70 percent effective in preventing hospitalization for flu or pneumonia. Among nursing home residents, a flu shot is 50 to 60 percent effective in preventing hospitalization and pneumonia, and 80 percent effective in preventing death from influenza.
In some cases, people who get a flu shot can still get the flu, but they may get a much less severe form of the illness and, most important, they'll have a decreased risk of flu-related complications — especially pneumonia, heart attack, stroke and death — to which older adults are especially vulnerable.
A study published in 2006 showed that the nasal spray flu vaccine (FluMist) was only between 30 and 57 percent effective in preventing the flu in adults. However, another study in 2006 found that giving nasal spray vaccine to school-age children helped reduce the spread of flu in the community. And in 2007, researchers compared the effectiveness of FluMist with the flu shot in children ages 6 months to 5 years. The children treated with FluMist experienced about half as many cases of flu as did those who received the shot. However, FluMist increases the risk of wheezing in this age group — especially in those who already have asthma or recurrent wheezing and in all children under age 2. FluMist is approved for children older than 2 years who don't have asthma or recurrent wheezing. Consult with your doctor about which form of vaccination may be best for you or your child.
Why do I need to get vaccinated every year?
You need annual flu protection because the influenza virus changes from year to year. The flu vaccine you got last year wasn't designed to fight the virus strains in circulation this flu season.
Influenza viruses mutate so quickly that they can render one season's vaccine ineffective by the next season. A CDC advisory committee meets early in the year to estimate which strains of influenza virus will be most prevalent during the upcoming flu season, and manufacturers produce vaccine based on those recommendations.
What are my options for the flu vaccine?
The flu vaccine comes in two forms:
- A shot. A flu shot contains an inactivated vaccine made of killed virus. The shot is usually given in the arm. Because the viruses in the vaccine are killed (inactivated), the shot won't cause you to get the flu, but it will enable your body to develop the antibodies necessary to ward off influenza viruses. You may have a slight reaction to the shot, such as soreness at the injection site, mild muscle ache or fever. Reactions usually last one to two days and are more likely to occur in children who have never been exposed to the flu virus.
- A nasal spray. Administered through your nose, the nasal spray vaccine (FluMist) consists of a low dose of live, but weakened, flu viruses. The vaccine doesn't cause the flu, but it does prompt an immune response in your nose and upper airways as well as throughout your body.
What are the main differences between the two types of flu vaccine?
Both the flu shot and the nasal spray help protect you from influenza. But there are differences to consider before deciding between the two.
| Flu shot | Nasal spray |
|---|---|
| Administered through a needle — you'll need a shot | Administered through a spray — you won't need a shot |
| Contains killed viruses — you can't pass the flu along to anyone else | Contains weakened live viruses that won't give you the flu but that can, in rare cases, be transmitted to others |
| Approved for use in people 6 months of age and older | Approved for healthy people ages 2 years to 49 years |
| Can be used in people at increased risk of flu-related complications, including pregnant women and those with chronic medical conditions | Given only to nonpregnant healthy people, not to those with chronic medical conditions, suppressed immune systems or to children and adolescents receiving aspirin therapy |
| May be available free to the uninsured and is usually covered by insurance | May not be covered by insurance |
Who should get the flu vaccine?
Most people who want to reduce the risk of getting influenza can get a flu shot. The CDC recommends the flu vaccine each year if you:
- Are age 6 months up to 19 years
- Are pregnant
- Are 50 years old or older
- Have a chronic medical condition such as asthma, diabetes, or heart, kidney or lung disease
- Have a weakened immune system such as from medications or HIV infection
- Are a resident of a nursing home or other long term care facility
- Are a child care worker or health care worker or live with or care for someone at high risk of complications from the flu
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