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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?

The The H1N1 swine flu vaccine, both the shots and the nasal spray, are made the same way as the seasonal flu vaccine.

Every year or so, the seasonal vaccine -- which includes a component based on the seasonal H1N1 virus -- is tweaked to match a flu virus that has changed its genetic makeup. The same kind of tweaking resulted in the H1N1 swine flu vaccine.

That's why the FDA approved it: They considered it just a strain change, and not a brand new vaccine.

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.

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