The common names we assign to illnesses are confusing, aren't they?

The "flu shot" protects against influenza--an infection caused by the influenza virus, which affects mostly the nose, throat, bronchi, and sometimes lungs. According to the World Health Organization,

"Infection usually lasts for about a week, and is characterized by sudden onset of high fever, aching muscles, headache and severe malaise, non-productive cough, sore throat and rhinitis."

While the symptoms are similar to those of the common cold, influenza is much more severe, and takes longer to recover from. And, of course, it can be deadly. According to the US Centers for Disease Control (CDC),

"Every year in the United States, on average 5% to 20% of the population gets the flu; more than 200,000 people are hospitalized from flu complications, and; about 36,000 people die from flu. Some people, such as older people, young children, and people with certain health conditions, are at high risk for serious flu complications."

"Stomach flu," medically known as viral gastroenteritis, could be caused by any of a whole bunch of viruses (rotaviruses, adenoviruses, Norwalk-type viruses, etc.) and affects the stomach and small intestine. Symptoms usually last 1-3 days.

Don't give up on flu shots because you've come down with gastroenteritis. It's kind of like saying you're not getting your tetanus shot because it didn't protect you against the chicken pox.

Hope you're feeling better soon.

Let's see: you're healthy and young, and you've had the flu twice in 4 years... Not exactly a great argument for not getting the shot! :)

You certainly have the right to refuse a flu shot. And you're not considered part of a high-risk category of people in any case. But what if you lived with or had a lot of contact with an elderly or infant relative? They don't have the same level of immunity and immune response as you do, and the complications can be dangerous for them.

Some people DO need flu shots.

I hear this a lot, but it just isn't so.

One risk associated with the flu shot is an increased chance of developing Guillain-Barre syndrome. (A recent study shows that a flu shot seems to increase the risk of Guillain-Barre by about 45%.) But the absolute risk of developing Guillain-Barre, even with a flu shot, is very, very low, while the benefit of getting a flu shot, in terms of preventing illness and lost work/school time, is high. (Here's what the CDC says about influenza vaccination and Guillain-Barre.)

Many people also worry about thimerosal (a preservative) in vaccines. According to the CDC,

"Today, all routinely recommended licensed pediatric vaccines that are currently being manufactured for the U.S. market, with the exception of influenza vaccine, contain no thimerosal or only trace amounts. Thimerosal preservative-free influenza vaccines are available, but in limited quantities. The total amount of inactivated influenza vaccine available without thimerosal as a preservative will continue to increase as manufacturing capabilities are expanded.

The majority of influenza vaccines distributed in the United States currently contain thimerosal as a preservative. However, some contain only trace amounts of thimerosal and are considered by the Food and Drug Administration (FDA) to be preservative-free. Manufacturers of preservative-free flu vaccine use thimerosal early in the manufacturing process. The thimerosal gets diluted as the vaccine goes through the steps in processing. By the end of the manufacturing process there is not enough thimerosal left in the vaccine to act as a preservative and the vaccine is labeled ‘preservative-free'.

At the current time, sanofi pasteur is projecting that 8 million to 9 million doses of thimerosal-free vaccine in pre-filled syringes or vials will be produced for the 2006-07 influenza season. The majority of this vaccine will be in 0.25 mL syringes (indicated for ages 6-35 months) with the remainder in 0.5 mL vials or syringes (indicated for ages 36 months and older). In addition, GlaxoSmithKline’s influenza vaccine for adults 18 years of age and older is preservative-free vaccine and Novartis (formerly Chiron) has a preservative-free preparation for persons 4 years of age and older. Also, the nasal-spray influenza vaccine (sold commercially as FluMist®) does not contain any thimerosal and can be given to healthy people 5 to 49 years of age who are not pregnant."

If you're young and healthy, and have no other high risk factors for influenza, you could skip the shot and not think too much about it. But if you have contact with people in higher risk groups, especially people who can't be vaccinated themselves for one reason or another, then you really should consider it.