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H1N1 Swine Flu Vaccine FAQ

WebMD provides a practical guide to the H1N1 swine flu vaccine.

Is the H1N1 swine flu vaccine safe? continued...

Even so, both long- and short-term clinical trials are under way. Results from the short-term studies already are here: Other than causing the usual soreness and perhaps redness at the site of injection, the vaccines cause no major side effects.

And like the seasonal flu vaccine, the H1N1 swine flu vaccine can't be taken by everybody. The vaccine is produced in hens' eggs, so people with egg allergies cannot take the vaccine.

Will there be long-term side effects? That's not likely -- but the CDC is taking no chances. The CDC and vaccine manufacturers have beefed up their safety monitoring process to look for anything unusual in people who get vaccinated against the new flu.

The most feared side effect of a flu vaccine is Guillain-Barre syndrome (GBS), a rare neurological condition that can result in paralysis and even death. Because the 1976 swine flu vaccine increased the risk of GBS, that vaccination program was aborted.

Seasonal flu vaccines slightly increase the risk of GBS by about one case per million people vaccinated. A June 2010 report from CDC found the 2009 H1N1 vaccine increased GBS risk by about the same amount: 0.8 cases per million people vaccinated.

An unprecedented level of safety monitoring -- including the military, an independent panel of experts, university campus health centers, and enhanced CDC surveillance -- has not revealed any unusual safety issues with the 2009 H1N1 flu vaccine.

Who should get the H1N1 swine flu vaccine?

Because Because it is a new virus to which humans have never before been exposed, everyone is vulnerable to H1N1 swine flu. That means everyone could benefit from the vaccine.

But certain groups are at particularly high risk of dangerous flu complications:

  • Children under age 5, especially those younger than 2 years old.
  • Adults age 65 and older
  • Pregnant women

In addition, certain medical conditions make it dangerous for a person to get the flu:

  • Asthma
  • Neurological and neurodevelopmental conditions including disorders of the brain, spinal cord, peripheral nerve, and muscle such as cerebral palsy, epilepsy (seizure disorders), stroke, intellectual disability (mental retardation), moderate to severe developmental delay, muscular dystrophy, or spinal cord injury  
  • Chronic lung disease (such as COPD and cystic fibrosis)
  • Heart disease
  • Blood disorders (for example, sickle cell disease)
  • Diabetes and other endocrine disorders
  • Kidney disorders
  • Liver disorders
  • Metabolic disorders
  • Weakened immune system due to disease or immune-suppressing therapy
  • People under age 19 on long-term aspirin therapy

If I think I've had swine flu, do I need the vaccine?

Even Even during a flu pandemic, colds and all kinds of flu-like illnesses circulate. In fact, most flu-like illnesses are NOT caused by the flu.

If you came down with a flu-like illness since April 2009, you may have had the H1N1 swine flu. But the only way to know for sure is if your doctor took a nasal or throat swab, sent it off to a lab, and had that lab confirm the infection.

If that didn't happen, it's not safe to assume you already had the flu. Especially if you're at risk of severe flu illness, it's a very good idea to get your H1N1 swine flu shot AND your seasonal flu shot. The vaccine is perfectly safe for people who actually had swine flu.

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