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Flu vaccines do work, but are not 100 percent effective in preventing seasonal influenza and will not protect us against pandemic flu. But getting a flu shot might lessen the severity of the flu and keep you from infecting people who are at high risk of suffering deadly, flu-related complications.
Flu viruses are constantly changing. Generally, new influenza virus strains circulate every flu season, so the vaccine is changed each year. When the viruses in the vaccine and circulating viruses are similar, the flu vaccine is about 70 to 90 percent effective in preventing flu among healthy adults.
Flu shots are recommended for all those at risk (see Key Point 1), plus anyone who shares a household or cares for someone at high risk of complications from flu. But, if people who are "not on the endangered list" also got flu shots, life could be a whole lot better for thousands of us during flu season.
Why doesn't everyone get a flu shot? There are lots of myths that make people hesitate.
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The Myth |
The Facts |
| Flu shots don't work |
In an average year, the flu vaccine is about 70 to 90 percent effective in preventing flu among healthy adults. See more about this topic below. |
| Getting the flu vaccine can give you the flu |
You may coincidentally get sick with a non-flu virus that has flu-like symptoms or you may get the flu after a shot because you were actually exposed to the flu virus prior to building sufficient antibodies. The most likely side effect of getting a flu shot is a sore arm. The alternative nasal spray 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. |
| Flu vaccine is dangerous |
There are some people who shouldn't get a flu shot, but for most people, the risk of a rare allergic reaction is far less than the risk of severe complications from influenza. People who shouldn't get a flu shot are:
- Anyone allergic to chicken eggs.
- Anyone who has had a severe reaction to a flu vaccine in the past.
- Children under 6 months of age.
- Anyone who has a fever or other severe illness.
- Anyone with Guillain-Barre syndrome that developed six weeks or less after receiving a flu vaccine.
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Additionally, people assume they won't be able to get a flu shot because of vaccine shortages. That's been the case over the past couple of years, but the Centers for Disease Control expects there will be enough vaccine to meet demands this year.
A flu shot gives you the best chance for avoiding the seasonal flu. But why can't it guarantee that you won't get sick?
First and foremost, no biological product is 100 percent effective. Plus there are many complexities when it comes to flu viruses. Influenza viruses change over time. Each year the vaccine is updated to include the viruses that are most likely to circulate in the upcoming influenza season. There are usually more types of flu out there than are covered by the vaccine. They can vary by region. They can even mutate, taking on new characteristics during the season. It takes time to produce vaccines, so a new one can't be instantly produced when a new strain of flu shows up.
The flu vaccine may be less effective in preventing illness than it is in preventing serious complications and death in elderly or chronically ill people. These at-risk people may not produce enough of an antibody response or it may not last the entire flu season. In other words, the flu vaccine tends to work best in the people who need it the least.
What about avian (bird) flu or a pandemic flu? An annual shot for seasonal flu won't protect you from either, but it will reduce the risk of simultaneously contracting both seasonal flu and another variety. Scientists are working on ways to prevent the spread of the H5N1 subtype of avian flu. In the face of a pandemic outbreak, countries will most likely take measures such as border closures and travel restrictions to limit its spread.
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