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Thursday, July 14, 2011

Study: Adjuvanted H1N1 vaccines had little effect on GBS risk

From Robert Ross at CIDRAP :

" A five-country study from Europe indicates that the use of adjuvanted vaccines against the pandemic H1N1 influenza virus probably did not increase the risk of Guillain-Barre syndrome (GBS), but the investigators could not firmly rule out a slightly greater chance of suffering the paralytic condition.

Writing in BMJ, the European researchers report that the adjusted odds ratio (OR) for GBS in those who were vaccinated was 1.0, indicating no higher risk, but the 95% confidence interval (CI) was 0.3 to 2.7, leaving the possibility open.

"The risk of occurrence of Guillain-Barre syndrome is not increased after pandemic influenza vaccine, although the upper limit does not exclude a potential increase up to 2.7-fold or three excess cases per one million vaccinated people," the report states.

GBS associated with flu vaccination has been a concern since the aborted US swine flu vaccination campaign of 1976, when almost one extra GBS case was reported per 100,000 vaccinations. Since then, studies of seasonal flu campaigns have shown no increase or only a slightly increased risk of 1 to 2 extra cases per million vaccinees, according to an editorial accompanying the BMJ report.

In Europe, the 2009 pandemic triggered the first widespread use of flu vaccines containing adjuvants: GlaxoSmithKline's Pandemrix and Novartis's Focetria, which were the most widely used vaccines there. The public's unfamiliarity with adjuvants has been cited as a factor in the generally low vaccine uptake during the pandemic in Europe. Adjuvants have not been used in US flu vaccines.

The European study was a case-control investigation conducted in Denmark, France, the Netherlands, Sweden, and the United Kingdom by the Vaccine Adverse Events Surveillance & Communication (VAESCO) consortium. The study period was November 2009 through March 2010."

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