Guillain-Barré syndrome reported in few Johnson & Johnson vaccine recipients: What is the rare nerve disorder?

A new warning from the Food and Drug Administration (FDA) over an elevated risk of a rare autoimmune nerve disorder among a small fraction of Johnson & Johnson COVID-19 vaccine recipients has sparked concern: What is Guillain-Barré syndrome?

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Guillain-Barré syndrome (GBS) occurs when a person’s immune system and inflammation damage the nerves, spurring muscle weakness and in some severe cases, paralysis, according to the Centers for Disease Control and Prevention (CDC).  It is a rare neurological disorder estimated to affect 3,000 to 6,000 Americans annually, per the FDA.

Triggers for the syndrome include recent respiratory or gastrointestinal infection weeks before symptoms, or other viral infections like the flu and Zika virus. The first symptoms typically involve weakness and tingling in the extremities, according to the Mayo Clinic, which notes no known cure and an estimated mortality rate ranging from 4% to 7%. Treatment typically requires hospitalization and involves plasma exchange and antibody infusions to alleviate symptoms and help speed up recovery.

Symptoms can last for several weeks to years, and while most will go on to fully recover, some are left with permanent nerve damage. 

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"Very rarely, people have developed GBS in the days or weeks after receiving certain vaccines," the CDC states. The FDA specifically notes the disorder has been observed at increased rates with certain seasonal influenza vaccines and a vaccine meant to prevent shingles.

The syndrome is estimated to affect about 1 in 100,000 people, and in the U.S. it is more common among men and individuals above age 50. It is not contagious but outbreaks of germs linked to GBS can result in clusters. 

The latest warning from the FDA advises seeking immediate medical attention upon symptoms post-vaccination like "weakness or tingling sensations (especially in the legs or arms) worsening or spreading to other parts of the body, difficulty walking, difficulty with facial movements including speaking, chewing or swallowing, double vision or inability to move eyes, or difficulty with bladder control or bowel function."

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The warning comes after about 100 preliminary reports of Guillain-Barré cases occurred against a backdrop of about 12.5 million Johnson & Johnson doses administered, the FDA said in a statement Monday. Of the total, 95 cases were serious and involved hospitalization, with one reported death. However, the FDA stopped short of pinning a causal relationship between the vaccine and the rare disorder.

"Although the available evidence suggests an association between the Janssen vaccine and increased risk of GBS, it is insufficient to establish a causal relationship," the statement reads, later adding, "Importantly, the FDA has evaluated the available information for the Janssen COVID-19 Vaccine and continues to find the known and potential benefits clearly outweigh the known and potential risks."