domingo, 14 de agosto de 2011

Is pandemic influenza A vaccination linked to Guillain-Barré syndrome ?

These European researchers examined whether there is a link between pandemic influenza A (H1N1) vaccination in 2009 and Guillain-Barré syndrome. They enrolled 104 patients with Guillain-Barré syndrome and Miller- Fisher syndrome(a variant) matched to one or more matched controls in a case control study.

The researchers found: "Case recruitment and vaccine coverage varied considerably between countries. The most common vaccines used were adjuvanted (Pandemrix and Focetria). The unadjusted pooled risk estimate for all countries was 2.8. After adjustment for influenza-like illness/upper respiratory tract infection and seasonal influenza vaccination, receipt of pandemic influenza vaccine was not associated with an increased risk of Guillain-Barré syndrome (adjusted odds ratio 1.0). The 95% confidence interval shows that the absolute effect of vaccination could range from one avoided case of Guillain-Barré syndrome up to three excess cases within six weeks after vaccination in one million people."

The researchers concluded: "The risk of occurrence of Guillain- Barré syndrome is not increased after pandemic influenza vaccine, although the upper limit does not exclude a potential increase in risk up to 2.7-fold or three excess cases per one million vaccinated people. When assessing the association between pandemic influenza vaccines and Guillain-Barré syndrome it is important to account for the effects of influenza-like illness/upper respiratory tract infection, seasonal influenza vaccination, and calendar time."
Fuente:  BMJ 343:d3908, 12 July 2011 © 2011 BMJ Publishing Group Ltd.
Guillain-Barré syndrome and adjuvanted pandemic influenza A (H1N1) 2009 vaccine: multinational case-control study in Europe. Jeanne Dieleman, Silvana Romio, Kari Johansen

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