(AP Photo/Eduardo Verdugo)

The flu can leave you with a rare, but terrible, neurological condition known as Guillain-Barre syndrome (GBS). The immune system attacks the nervous system and eventually a small handful of people end up paralyzed, sometimes unable to breathe on their own. (Other things, including campylobacter jejuni bacteria, can lead to GBS too.)

Problem is, in rare cases, the flu vaccine may also increase the risk of developing GBS.

So if you're worried about the small chance of developing this horrible syndrome, do you take your chances with the flu or the flu vaccine? Health-care workers, in particular, cite GBS as a reason they avoid the vaccine--even though the syndrome affects only 1 in 100,000 people in the United States.

Researchers at the Ottawa Hospital Research Center have crunched the numbers and determined that, in most cases, you are better off getting the vaccine. For a hypothetical 45-year-old woman, they found, the vaccination actually decreased the risk of GBS by one chance in every 2.7 million vaccinations. For a 75-year-old man, it would be one fewer case for every 2.4 million people vaccinated,, according to their study, published Wednesday in the Centers for Disease Control and Prevention journal Emerging Infectious Diseases.

"We found that most of the time, getting the vaccine actually reduces your risk of GBS" over not getting it, said Kumanan Wilson, a professor of internal medicine at Ottawa Hospital. Only if you got a flu shot for a flu season when little virus was circulating would the numbers change substantially.

Wilson and his colleague, epidemiologist Steven Hawken, also have developed this nifty interactive scale that allows you to calculate your own GBS risk, accounting for gender, age and flu circumstances.

Fear of GBS and the vaccination date way back to 1976, when GBS increased among people who got the vaccine to protect against the swine flu virus. According to the CDC, scientists aren't entirely sure why. Given the potentially catastrophic nature of GBS--there are treatments but no cure--and the growing anti-vaccination movement, fear of the flu vaccine has grown out of proportion, Wilson and Hawken said.

"It is rare after the vaccine, but it scares a lot of people, and health-care workers," Wilson said.