INSIGHT-GSK vaccine ingredient scrutinised for narcolepsy clues

Fri Feb 8, 2013 4:31am EST
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By Kate Kelland, Health and Science Correspondent

LONDON Feb 7 (Reuters) - Mounting evidence of a link between GlaxoSmithKline's Pandemrix flu shot and a spike in narcolepsy cases among children in Europe is putting one of the vaccine's key ingredients, AS03, under intense scrutiny.

The ingredient is one of a class of pharmaceuticals known as adjuvants, or boosters, designed to turbo charge the potency of a vaccine and the body's immune response to it.

AS03 was widely used in Europe during the 2009-2010 H1N1 flu pandemic and is also contained in a GSK adjuvanted flu vaccine which in November last year became the first of its kind to be recommended for approval by the normally adjuvant-wary United States Food and Drug Administration (FDA)

There's little doubt AS03 does its job well.

Pandemrix, the flu vaccine under suspicion for the narcolepsy link, needs only a fraction of the antigen - the part that actually does the immunisation - of other flu shots to give sufficient protection.

This means the manufacturer - in this case GSK - can produce multiple times the number of vaccine doses without needing to spend valuable time making large amounts of the antigen.

In a pandemic situation in which the lives of millions around the world are under threat, that could make the difference between having enough vaccines to protect entire populations, or having to decide how to ration them out.

Yet some experts believe the turbo-charged immune response AS03 generates, or the ingredients that drive it, may also be the answer to why almost 800 cases of the incurable sleeping disorder narcolepsy have been linked to Pandemrix's use in Europe during the 2009/2010 H1N1 pandemic.   Continued...