Guillain-Barré Syndrome and Vaccines

Questions and Concerns

Guillain-Barré syndrome (GBS) is a rare disorder where the body’s immune system damages nerve. The damage to the nerves causes muscle weakness and sometimes paralysis. While its cause is not fully understood, the syndrome often follows infection with a virus or bacteria. Each year in the United States, an estimated 3,000 to 6,000 people develop GBS. Most people fully recover from GBS, but some have permanent nerve damage.

GBS is rare.

Anyone can develop GBS, but people older than 50 are at greatest risk. About two-thirds of people with GBS were sick with diarrhea or respiratory illness days or weeks before developing symptoms. Infection with the bacteria Campylobacter jejuni, which causes gastroenteritis (including symptoms of nausea, vomiting and diarrhea), is one of the most common risk factors for GBS. People also can develop GBS after having the flu or other infections such as cytomegalovirus and Epstein-Barr virus. On very rare occasions, people develop GBS in the days or weeks after getting a vaccination.

To study whether a new vaccine might be causing GBS, CDC compares the usual rate of GBS to the observed rate of GBS in vaccinated people. This helps to determine whether a vaccine could be causing more cases.

GBS and the link to flu vaccine

In response to a potential pandemic strain of a flu virus in 1976, there was a national campaign for people to get the swine flu vaccination. Over 45 million people were vaccinated and there were increased reports of GBS following vaccination. Those who received the 1976 swine flu vaccine had a slight increased risk for developing GBS of approximately one additional case of GBS for every 100,000 people who got the swine flu vaccine. Scientists have several theories about the cause, but the exact reason for this link remains unknown.

CDC monitors GBS cases during each flu season. From data collected, the association between seasonal flu vaccine and GBS has been found to vary from season to season. When there has been an increased risk, it has consistently been in the range of 1-2 additional GBS cases per million flu vaccine doses administered.

Additional studies have been conducted on the risk of GBS following flu vaccination. Results of these studies suggest that it is more likely that a person will get GBS after getting the flu than after vaccination. It is important to keep in mind flu infection can potentially cause severe illness and death. The best way to prevent flu infection and its complications is to get the flu vaccine.

CDC and FDA closely monitor the safety of all vaccines.

CDC and the Food and Drug Administration (FDA) are committed to ensuring that all vaccines are as safe as possible. Once vaccines are licensed in the United States, they are continuously monitored through several safety systems and programs. Learn more about the nation’s vaccine safety efforts.

Related Scientific Articles