GSK’s pandemic flu vaccination significantly increases the risk of children developing a serious sleep problem, according to a study conducted by the U.K. Health Protection Agency. The study confirms findings that have been found in other European studies.


Over 30 million doses of GlaxoSmithKline plc (NYSE:GSK) (LON:GSK)’s Pandemrix swine flu vaccine were handed out during the H1N1 pandemic between 2009 and 2010. Today a research study published by scientists in the U.K. said the vaccine might have caused an adverse immune reaction in children who have a higher genetic tendency toward narcolepsy.

The study was published in the British Medical Journal, and it found that GSK’s vaccine carried a risk of one case of the sleep disorder for every 55,000 children who received the vaccine. That’s 14 times as high as the background risk for developing the disorder.

Narcolepsy is believed to be an autoimmune disease, and its most well-known symptom is sudden daytime sleepiness. There is no cure for the disorder.

The new study indicates that about 700 childhood cases of narcolepsy in Europe may be linked with GSK’s vaccine. The study did not find any indications that Pandemrix also increased the risk of adults developing the sleep disorder.

Researchers said the disorder seemed to develop within months of receiving GlaxoSmithKline plc (NYSE:GSK) (LON:GSK)’s Pandemrix vaccine. They said there was no sign that other flu vaccines were also linked with narcolepsy.

GlaxoSmithKline plc (NYSE:GSK) (LON:GSK) officials don’t believe there is a causal connection between the vaccine and the sleep disorder. Some experts have speculated that a powerful immune system booster added to the vaccine may play a role in triggering narcolepsy, but there is no concrete evidence to prove those speculations.