New findings may ease fears about a connection between flu vaccines and Guillain-Barre Syndrome (GBS), French researchers say.
They found that people who received a flu shot were no more likely to get GBS than people who didn't get the shot. In fact, the flu virus itself, rather than the vaccine, "is a likely risk factor for GBS," they said in a report online in the American Journal of Epidemiology.
Using data from 25 neurology clinics in France from 2007 to 2010, Dr Lamiae Grimaldi-Bensouda at LA-SER and Institut Pasteur in Paris and colleagues identified 145 patients diagnosed with GBS. They compared these to 1,080 age-, gender-, and region-matched controls.
The researchers also looked at how many people had received either the seasonal flu shot or the H1N1 pandemic vaccine.
Overall, 17% of patients with GBS had received a flu vaccine within six months of the start of their symptoms. In comparison, 21% of controls had received the vaccine within six months of their last visit to the doctor.
The researchers also observed that people with GBS were more than twice as likely as controls to have had the flu or to have taken flu medication (suggesting they had a flu-like illness) in the two months prior to developing GBS.
The study does not necessarily rule out a connection between the vaccine and GBS, said Dr Roger Baxter of Kaiser Permanente in Oakland, California in an email. However, getting the flu is likely a bigger risk factor for GBS than getting the vaccine, he said.
Mindful of the association between GBS and the 1976 swine flu scare, which involved an influenza A/H1N1 strain from pigs that never did spread among people but spurred a mass-vaccination campaign, the French researchers expanded their canvassing of neurology clinics during the 2009 "novel H1N1" flu pandemic.
They hoped to be able to detect any spike in GBS cases that might be linked specifically to the new H1N1 vaccine. Instead, they found a very slightly lower risk for GBS among recipients of the pandemic vaccine compared to people receiving seasonal flu vaccines. (Reuters Health, June 2011)