The European Commission asked the European Medicines Agency (EMEA) to investigate whether GlaxoSmithKline's flu jab, Panemrix is linked to a higher risk of developing narcoplepsy. The EMEA says the investigation is now underway. Some cases of narcolepsy were reported in Finland and Sweden - the EMEA says they were all "collected through spontaneous reporting systems".
Pandemrix has been in use since September 2009 for protection against H1N1 influenza (informally known as swine flu). Over 30 million Europeans have been given the shot, according to EMEA.
Narcolepsy is a chronic sleep disorder where the brain is unable to regulate the body's sleep-wake cycles. People with narcolepsy may feel an overwhelming urge to sleep at various points in the day, and they will often fall asleep spontaneously for a few seconds to a few minutes. In extreme cases, people with narcolepsy will remain asleep for over an hour. Currently, we do not know the exact causes of narcolepsy. Researchers have suggested that there may be a genetic role in the condition or something such as an infection that triggers the condition. There is also some evidence that a brain chemical called hypocretin plays a role in narcolepsy. Hypocretin helps regulate staying awake and keeps rapid eye movement (REM) sleep stable and occurring at the correct times. In people with narcolepsy, hypocretin levels are found to be very low. However, we do not know what causes damage to hypocretin cells - perhaps an infection or abnormal immune system response.
Although the narcolepsy cases that have been reported occurred a short time after the patients received a Pandemrix shot, the EMEA stresses that nobody knows what caused the disorder in those individuals. The CHMP (Committee for Medicinal Products for Human Use) will check all available data to determine whether there is evidence of a causal link.
The CHMP will check background epilepsy rates against the current ones where the flu shot has been used.
The EMEA says the Committee will consider at its September 2010 meeting whether there is a need for any provisional measures after experts have carried out their investigation.
The Agency is also in communication with the European Centre for Disease Prevention and Control (ECDC), international regulatory partners and the World Health Organization (WHO).
On 24th) August, the National Institute for Health and Welfare, Finland recommended that Pandemrix shots be halted until the suspected association with narcolepsy is thoroughly evaluated. (Link)
Written by Christian Nordqvist
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