A swine flu jab has been linked to rare cases of a sleeping disorder and should be the last line of protection for young people, European regulators say.
The European Medicines Agency (EMA) said Pandemrix should only be given to children and teenagers at risk of H1N1 flu if other jabs are unavailable.
More than six million doses of the vaccine have been given in the UK.
Ten suspected cases of narcolepsy linked to the vaccine have been reported to the UK’s drug regulator.
Pandemrix, made by GlaxoSmithKline (GSK), was the most widely used in the UK during the 2009/10 flu pandemic.
However, the vaccine is no longer in use and the remaining stocks will be destroyed this autumn.
The EMA’s investigation followed reports, mainly from Finland and Sweden but also from Iceland and the UK, of children and adolescents suffering the sleep disorder narcolepsy, which causes people to fall asleep suddenly and unexpectedly.
It said studies had shown a six to 13-fold increased risk of narcolepsy in children and adolescents vaccinated with Pandemrix compared with unvaccinated children.
In a statement, the EMA said it had “noted that the vaccine is likely to have interacted with genetic or environmental factors which might raise the risk of narcolepsy, and that other factors may have contributed to the results.”