The supercharged vaccines used to fight the H1N1 epidemic in 2009 may not have boosted the risk.
Guillain-Barre is a rare disorder which causes a person's immune system to damage nerve cells, resulting in muscle weakness and even paralysis.
In 1976, a vaccine used during a flu outbreak was linked to the disease, but a new study in the journal BMJ finds H1N1 posted little if any increased risk for the disease.