As the state sends mobile units from town to town to increase vaccination rates, the Johnson & Johnson shot is causing more worries. The FDA is now warning of a potential increased risk of a nerve complication called Guillain-Barré syndrome. Doctors say the roughly 100 cases reported after nearly 13 million shots should not be alarming, but health officials are closely monitoring the rare, yet serious, complications. Guillain-Barré syndrome is marked by muscle weakness and even paralysis. Doctors say it’s been linked to other vaccines like the flu shot.