Europe’s drug regulator has opened an investigation into the safety of a swine-flu vaccine to see if it is linked to suspected cases of narcolepsy.
Narcolepsy is a rare disorder that causes people to fall asleep suddenly.
The European Medicines Agency opened the inquiry after 27 suspected cases were reported in Sweden, Finland and France by people who had received the shot known as Pandemrix.
Pandemrix is produced by the British pharmaceuticals giant GlaxoSmithKline.
Dr Carmen Kreft-Jais, an official with the French Pharmaceutical Safety Agency, said there had been six cases of narcolepsy reported in France by people who had used Pandemrix.
The bulk of cases have been reported in Sweden and Finland where authorities are conducting their own investigation into the vaccine.
30 million Europeans have received the jab since the European Medicines Agency approved
its use last September.
The precise cause of narcolepsy is unknown but it is believed to be triggered by genetic and environmental factors such as infections.
GlaxoSmithKline said in a statement: “The currently available information is insufficient to assess the likelihood of a causal relationship between Pandemrix and narcolepsy.”