The World Health Organisation has called for a closer look at a potential link between GlaxoSmithKline's pandemic swine flu vaccine Pandemrix and the development of the chronic sleep disorder narcolepsy.

The group's Global Advisory Committee on Vaccine Safety said in a statement that "further investigation is warranted" after a 12 different countries reported cases of the condition in children and adolescents following vaccination with GSK's product.

But, interestingly, rates reported from Iceland, Sweden and Finland "have been notably higher than those from other countries", the Committee said. According to GSK, over 31 million doses of its vaccine have been administered in 47 countries. A total of 162 cases of narcolepsy in people vaccinated with Pandemrix have been reported to the drugmaker, of which 70% originated from Finland and Sweden.

Just last week, a systemic review in Finland found a higher risk of narcolepsy among those aged four-19 years old who had received the vaccine compared with those who had not, and concluded that the risk of developing the condition was about nine times higher, equating to an overall risk of about one case of narcolepsy per 12,000 vaccinated in this age group.

The National Institute for Health and Welfare of Finland thinks it probable that Pandemrix was a contributing factor to the increase, and so called for further investigation of other co-factors that could boost this risk. According to the Institute, it is likely that GSK's vaccine raised the risk of narcolepsy in those genetically disposed to the condition alongside some other, as yet undetermined, genetic and/or environmental factor.

Local phenomenon?

GACVS has agreed that a further investigation into the potential relationship is needed, but notes that, even at this stage, "it does not appear that narcolepsy following vaccination against pandemic influenza is a general worldwide phenomenon and this complicates interpretation of the findings in Finland". 

In an emailed statement to PharmaTimes World News, a spokesman for GSK said "it would be premature to draw any conclusions on a potential association between Pandemrix and narcolepsy" until an ongoing investigation by the European Medicines Agency, separate from that in Finland, is complete.