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Flu Vaccine FAQ

What the CDC Wants You to Know About the 2010-2011 Flu Vaccine

I got a flu shot a few years ago -- and a few days later I came down with the flu. Instead of risking this again, wouldn't I be safer just avoiding sick people? continued...

Keep in mind that the flu shot cannot produce a flu infection. It is dead -- it's just protein, with nothing live in it. So a lot of this is just coincidence -- either the vaccine did not have time to work, or you got something like the flu.

But this is a very common perception, linking your flu shot to getting the flu. Even some doctors and nurses have this perception. The way our brains work is to have two things happen in sequence, and to conclude that the two things are connected by cause and effect. Vaccination is memorable, and the illness is memorable, and it is human nature to think one caused the other. But it is a perceptual problem rather than reality.

What about the FluMist inhaled vaccine? Isn't that a live virus? Can't that give me the flu?

FluMist is a really good option for people who are healthy and under 50 and not pregnant. It is live, but it has been modified so it only grows in a person's nose or throat. It does not get down into the lung. It is modified so it does not cause lung infection.

This means the virus in FluMist does not cause flu the way we think of it as a respiratory infection. It can cause a sore throat for a day or two, but not flu with cough or fever. It really does not do that.

Flu season again? I got my shots last year and the year before. Why do I need another one?

The problem is the flu virus: It changes all the time. This means we have to change the vaccine all the time to keep up.

Last year's vaccine is not like this year's vaccine. There are three different viruses that can cause flu. Vaccines that protect against each one are included in the 3-in-1 seasonal flu vaccine. One or more of these components is changed every year because the virus we are trying to prevent has changed.

Unfortunately, being immune to one of last year's viruses may not protect you against this year's virus. It is a constant job of catch-up. And there probably is some waning of immunity over time, too, particularly with the shots.

Researchers are looking for a way to make a vaccine that is not so sensitive to change in the virus. We are looking for a one-shot vaccine that will protect for years after a single dose. That is what we would all like, a flu vaccine you could get every five or 10 years. But that vaccine has yet to be invented.

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