Weighing Possible H1N1 Vaccine Risks

Many are concerned about whether a H1N1 vaccine will be safe. But now reports are out that a swine flu vaccine could cause GBS or Guillian-Barre Syndrome, a brain disorder.

CBS News medical correspondent Dr. Jennifer Ashton explained on "The Early Show" Monday the risk of GBS is very low -- one in every million vaccinations.

Ashton explained GBS is a rare, neurologic disorder that has elements of an auto-immune condition in that some trigger (usually an infection or rarely a vaccination against an infection) results in a progressive weakening of nerves. GBS starts in the legs and works its way up the body. Estimates are that it may occur one time out of 100,000 or one million vaccine doses. In most cases, Ashton said, patients recover approximately four weeks from the first symptoms, and 80 percent of people have a complete recovery. Some however, can die from GBS; the death rate is quoted as 2 to 3 people in 100.

And some did die from GBS in 1976 when an outbreak of swine flu at Fort Dix, N.J. prompted widespread vaccine use after one soldier died from influenza. As the flu spread through Fort Dix, it was discovered that there was the regular type of influenza, but also the swine flu. Some scientists thought it was an indication of a return of the deadly flu from 1918 that killed 50 million worldwide. They quickly developed a vaccine, but the epidemic they were fearing never happened.

However, according to Ashton, it was never determined that what happened in 1976 was caused by the vaccine. Forty million Americans were vaccinated, and 500 cases of GBS were reported with 25 deaths.

"This is actually less than -- or at most equal to -- the expected rate of this disease in the general population," Ashton told CBS News. "It is a difficult determination to make with 100 percent certainty, but for the people who were affected, and who thought it was due to the vaccine, obviously it was devastating."

But should you get the vaccine for H1N1 when it is scheduled for released in October?

Ashton said it should be a personal decision based up risk versus benefit.

"If you are at high-risk for serious complications of influenza, then if many people get H1N1, your risk of getting sick is probably greater than your risk of having a rare side effect. And the possible benefit may be life-saving for some people. You have to weigh the risks of getting influenza, and the risk of possibly dying from it."

The risk of death from H1N1, Ashton said, is roughly 1 in 1000 people. She said you should weigh that risk against getting vaccinate, which, however safe the vaccine may be, the risk is never zero.

"People need to make those difficult decisions for themselves with good education and information from reputable sources," Ashton said. "I respect both decisions. Ultimately it's up to the patient."