Objective: Review of case reports of possible adverse events following immunization (AEFI) after vaccination with an influenza vaccine in the past three years.
Design: Descriptive, retrospective.
Method: Lareb (Netherlands Pharmacovigilance Centre) investigated and reviewed reports of possible AEFI after vaccination with an influenza vaccine over seasons 2010-2011, 2011-2012 and 2012-2013.
Results: Over the three seasons we received a total of 531 reports after administration of seasonal influenza vaccination. Each year the number of reports increased, especially the reports directly from vaccinees. In 32 cases (6%) the report was considered 'serious', in most cases it was associated with hospitalization. Two reports mentioned that the patient died but a causal relationship with the vaccination was considered unlikely. There were three reports of acute severe reactions, with anaphylaxis, angio-oedema and cardiac arrest. A total of 961 possible AEFI were reported. In 256 (over 25%) AEFI inflammatory symptoms occurred at the injection site. Besides the injection site reactions, headache (101), myalgia (90) and pyrexia (86) were the most reported AEFI. Notably, there were 26 reports of extensive limb swelling, in which injection site inflammation extends beyond shoulder or elbow or around the upper arm. The clinical picture resembles cellulitis or an allergic reaction and usually disappears with symptomatic treatment. Its aetiology is unknown.
Conclusion: Apart from extensive swelling of the limb, we did not find signs of unknown side effects of influenza vaccination. Based on the reported AEFI, influenza vaccines seem to be safe.