Probe of suspected vaccine-narcolepsy link to take months

Sep 23, 2010 (CIDRAP News) – The European Medicine Agency (EMA) said today it is not clear if there is any link between narcolepsy cases and the Pandemrix vaccine for 2009 H1N1 influenza, and it will take 3 to 6 months to investigate the possibility fully.

The EMA's Committee for Medicinal Products for Human Use (CHMP) concluded that further studies are needed, the agency said in a news release. In the meantime, the panel agreed that there is no need to restrict the vaccine's use, as the benefit-risk balance continues to be positive.

The EMA launched a review of Pandemrix on Aug 27, in the wake of reports of narcolepsy in vaccinees, mainly from Sweden and Finland. The vaccine, which is made by GlaxoSmithKline and contains an adjuvant, was administered to 30.8 million Europeans during the H1N1 pandemic.

As of Sep 17, there were 81 reports from healthcare professionals suggesting narcolepsy, all collected through spontaneous reporting systems, the EMA said today. These included 34 from Sweden, 30 from Finland, 10 from France, 6 from Norway, and 1 from Portugal. Another 13 "consumer reports" have come from Sweden and 2 from Norway. Patients range from 4 to 52 years old.

"The ongoing review is complex and will take some three to six months to complete," the EMA said. "The Agency is working with experts from across the European Union to carefully scrutinize all available reports. Owing to a potential overlap of narcolepsy symptoms with several other neurological and psychiatric disorders, diagnosis is very often not confirmed until several years after symptom onset."

Recent reports of narcolepsy in children seem to outnumber those in previous years for some countries, but many uncertainties need to be clarified, the EMA said. Earlier diagnoses of narcolepsy might have contributed to the apparent increase, and the H1N1 pandemic itself might have influenced the numbers, the statement said.

About 2 weeks ago, Swedish regulators said their own preliminary investigation had shown no link between narcolepsy cases and Pandemrix.

On Sep 1 the US Centers for Disease Control and Prevention said it had reviewed information from the Vaccine Adverse Event Reporting System and found no signs of a connection between narcolepsy cases and the H1N1 and seasonal flu vaccines used in the United States, where Pandemrix is not licensed.

See also:

Sep 23 EMA news release

Sep 9 CIDRAP News story "Sweden finds no link between H1N1 vaccine, narcolepsy"

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