Data published recently in the British Medical Journal found that children in England who received GSK’s Pandemrix vaccine during the 2009-10 H1N1 swine flu pandemic had a 14-fold heightened risk of developing narcolepsy, a chronic and potentially debilitating sleep disorder that can cause hallucinations, daytime sleepiness and cataplexy, a form of muscle weakness precipitated by strong emotion.
Authors of the study – whose results echo those of similar studies in Sweden, Finland and Ireland – said the data had implications for the approval and use of future vaccines that, like Pandemrix, contain AS03, a new adjuvant, or booster, that turbo-charges the body’s immune response to the vaccine.
Scientists believe AS03 may be the culprit in the narcolepsy cases though they have yet to decipher the precise nature of the association.
That uncertainty poses a challenge for the U.S. Food and Drug Administration, which is considering an AS03-containing vaccine for use in the event of an H5N1 bird flu epidemic. Like Pandemrix, which has not been approved in the United States, it is made by GSK and is almost identical in structure.
A 14-member panel of advisors to the FDA voted unanimously in November to recommend the vaccine to protect against bird flu. The panel considered early studies from Europe showing an increase in the number of narcolepsy cases but concluded that the potential benefit of the vaccine outweighed the risk.