March 13, 2013
1 min read

Slight risk for Guillain-Barré syndrome attributed to H1N1 vaccine

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Data from a meta-analysis show that there may be a slight risk for Guillain-Barré syndrome associated with the influenza A (H1N1) 2009 monovalent inactivated vaccine.

“On an individual level, we cannot predict with certainty who will contract influenza, who will have a serious complication or die from the disease, or who will have a very rare but serious adverse event from the vaccine,” Daniel Salmon, PhD, MPH, of the National Vaccine Program Office, said in a press release. “The safety monitoring program for influenza A (H1N1) 2009 monovalent inactivated vaccine did not identify any other serious adverse events associated with the vaccine.”

Salmon and colleagues used data from six different adverse event monitoring systems to conduct the analysis, which included approximately 23 million people who received the influenza A (H1N1) vaccine. They identified 77 cases of Guillain-Barré syndrome. The incidence rate ratio was 2.35 (95% CI, 1.42-4.01). When assuming a background rate of one case per 100,000 person-years, the rate ratio translated to 1.6 excess cases per 1 million vaccinations.

“About 61 million cases of influenza A (H1N1) disease were reported in the US during the 2009 pandemic, which included about 274,000 H1N1-related admissions and about 12,470 deaths,” Salmon said. “Clinicians, policymakers and those eligible for vaccination must consider the overall risks and benefits of vaccination, as defined by epidemiological studies, but should be assured that the benefits of influenza A (H1N1) 2009 monovalent inactivated vaccines greatly outweighed the risks.”

Disclosure: Salmon reports no relevant financial disclosures.