Guillain-Barré (ghee-yan bah-ray) syndrome is a disorder in which the body’s immune system attacks part of the peripheral nervous system. The first symptoms of this disorder include varying degrees of weakness or tingling sensations in the legs. In many instances, the weakness and abnormal sensations spread to the arms and upper body. These symptoms can increase in intensity until the muscles cannot be used at all and the patient is almost totally paralyzed. In these cases, the disorder is life-threatening and is considered a medical emergency. The patient is often put on a respirator to assist with breathing. Most victims, however, recover from Guillain-Barré syndrome, although many continue to exhibit weakness and are susceptible to reoccurrence.

While Guillain-Barré syndrome is relatively uncomon and can occur after surgery and viral infection, vaccination has been thoroughly documented as a primary cause of this disease.

The disorder can develop over the course of hours or days, or it may take up to 3 to 4 weeks, so it’s difficult to ascertain exactly how many cases follow vaccination and there has been no significant effort to try.