For years now, evidence has been mounting that a GlaxoSmithKline flu vaccine may have caused narcolepsy in nearly 800 Europeans who received the shot. Now the jab's adjuvant--designed to boost the potency of the vaccine--is under the microscope as the potential cause of the spike in cases of the sleeping disorder.
Though the European Medicines Agency declared last October that links between spikes in narcolepsy in European countries and a swine flu vaccine distributed in 2009 are insufficient, some experts still assert that the shot is to blame, and compelling evidence is growing.
The European Medicines Agency began a review of the vaccine's safety in 2010. On Friday, the agency announced that evidence presented so far does not lead to any new concerns regarding the safety of the vaccine.
Finnish researchers found that the chance of narcolepsy was much higher in children who received a certain flu vaccine.