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Content on this page was developed during the 2009-2010 H1N1 pandemic and has not been updated.

  • The H1N1 virus that caused that pandemic is now a regular human flu virus and continues to circulate seasonally worldwide.
  • The English language content on this website is being archived for historic and reference purposes only.
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Fact Sheet: Guillain-Barré Syndrome (GBS)

December 15, 2009, 3:30 PM ET

Guillain-Barré syndrome is rare

Guillain-Barré syndrome (GBS) is a rare disorder in which a person’s own immune system damages the nerves, causing muscle weakness and sometimes paralysis. GBS can cause symptoms that last for as little as a few weeks, or go on for several months. Most people recover fully from GBS, but some people have nerve damage that does not go away. In rare cases, people have died of GBS, usually from not being able to breathe due to weakness of their breathing muscles.

GBS may have several causes

While it is not fully known what causes GBS, it is known that about two-thirds of people who get GBS do so several days or weeks after they have been sick with diarrhea or a lung or sinus illness. An infection with the bacteria Campylobacter jejuni, which can cause diarrhea, is one of the most common illnesses linked to GBS. Although rare, people can also get GBS after having the flu or other infections such as Epstein Barr virus. Except for the swine flu vaccine used in 1976, no other flu vaccines have been clearly linked to GBS.

GBS is more common in older adults

Anyone can get GBS, but it is far more common in adults than children. Adults over 50 years of age are 2-3 times more likely to get GBS than younger people. Each year, between 6,000 and 9,100 people in the United States get GBS. This means that about 140 people get GBS every week.

Getting GBS from a vaccination is very rare

In very rare cases, someone may develop GBS in the days or weeks after getting a vaccination. In 1976, there was a small increased chance of GBS after getting a flu (swine flu) vaccination. This means about 1 more case per 100,000 people who got the swine flu vaccine.

Many studies have looked at seasonal flu vaccines and GBS

Since 1976, many studies have been done to see if other flu vaccines may cause GBS. In most studies no link was found between the flu vaccine and GBS. However, two studies did suggest that about 1 more person out of 1 million people vaccinated with seasonal flu vaccine may develop GBS. This continues to be studied.  For the most part, the chance of getting very ill from flu is far higher than the chance of getting GBS after getting the flu vaccine.

CDC has many systems to identify GBS cases

Since GBS is a serious disorder that people get every year, CDC has developed several GBS surveillance systems. These are tracking systems to better see whether some GBS cases are linked to flu vaccinations. During the 2009-2010 flu season, CDC and FDA are closely looking at reports of serious problems, including GBS, which may be linked to the use of the 2009 H1N1 flu vaccine and to the seasonal flu vaccine. These systems include the Vaccine Adverse Event Reporting System (VAERS), the CDC Emerging Infections Program, and a partnership with the American Academy of Neurology, which includes doctors who are most likely to see people with GBS. None of these systems existed in 1976. Through these systems, CDC and FDA are able to find any possible link between GBS and seasonal or 2009 H1N1 flu vaccines as early as possible and take appropriate action.

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