Passive surveillance of adverse events of an MF59-adjuvanted H1N1v vaccine during the pandemic mass vaccinations

Introduction: Systemic safety surveillance is an essential component of vaccination programs to elucidate the full safety profile of a vaccine and to detect previously unrecognized adverse reactions that might be related to new vaccines. This article summarizes the spontaneous adverse drug reactions (ADR) from approximately 12 million administered doses of the pandemic MF59-adjuvanted H1N1v vaccine (Focetria (R), Novartis Vaccines and Diagnostics) from the mass vaccination programs in Europe. Results: In the reporting period we received a total of 5,315 pandemic vaccine ADR reports, of which 19.9% were serious. The reporting rate was higher after H1N1 pandemic vaccines, i.e., 44.3 cases/100,000 doses, than for seasonal influenza vaccines covering the same time period, i.e., 1.7 cases/100,000 doses. The majority of reports included expected local and systemic postvaccination reactions. Rates for adverse events of special interest, for example, Guillain-Barre syndrome, anaphylaxis and convulsions showed no signs of disproportionality between the pandemic and the seasonal vaccines. There were 36 deaths reported after use of the pandemic vaccine; however, no evidence for a causal relationship with the vaccine was found. Methods: All ADR reports from October 2009 to March 2010 were included in the analyses and classified according to Medical Dictionary for Regulatory Activities. Adverse events of special interest were compared with pooled spontaneous case reports for seasonal influenza vaccines and signal detection analyses were performed. Conclusion: The analyses of the spontaneously reported adverse events support the good safety profile of the MF59-adjuvanted H1N1v pandemic influenza vaccine.