Surveillance identifies few serious adverse events, no increased risk of Guillain-Barré
WEDNESDAY, Feb. 2 (HealthDay News) -- Adverse events associated with influenza A (H1N1) vaccine appear to be limited and relatively rare, and there is no evidence of an increased risk of Guillain-Barré syndrome associated with the virus, according to research published online Feb. 2 in the New England Journal of Medicine.
Xiao-Feng Liang, M.D., Ph.D., of the Chinese Center for Disease Control and Prevention in Beijing, and colleagues collected data on 89.6 million doses of H1N1 vaccine administered in 2009 and 2010 to assess the safety of China's vaccination program.
The researchers identified 8,067 adverse events, or 90 per one million doses. Adverse events were higher in children aged 9 or younger and lower in adults over 60, at 130.6 and 31.4 per one million doses, respectively. A total of 6,552 of the adverse events (81.2 percent) were confirmed as vaccine reactions, and 13.4 percent of the adverse events were identified as rare and more serious; almost all of these were allergic reactions. The rate of Guillain-Barré syndrome reported -- 0.1 per one million doses -- was lower than China's background rate.
"No pattern of adverse events that would be of concern was observed after the administration of influenza A (H1N1) vaccine, nor was there evidence of an increased risk of the Guillain-Barré syndrome," the authors write.