The vaccines used in the U.S. against the pandemic H1N1 flu were associated with a modestly increased risk of Guillain-Barré syndrome, researchers reported. A meta-analysis of data from six vaccine safety surveillance systems showed that incidence of Guillain-Barré among vaccinated people more than doubled in the few weeks after the shot, compared with a longer time period after the shot, according to Daniel Salmon, PhD, of Johns Hopkins Bloomberg School of Public Health, and colleagues.
