Objective: To describe adverse events occurring after mass vaccination with conjugate and nonconjugate vaccines and to assess the incidence of serious adverse effects. Methods: A mass immunisation campaign against meningococcal C disease was conducted in two French administrative areas, Landes and Pyrenees atlantiques, for 2 months (from October to December 2002). Adverse events were reported by families and physicians by means of a specific reporting form returned to the pharmacovigilance centre 15 days after vaccination. Results: The target population was 260,630 individuals aged between 2 months and 24 years. About 179,000 children and young adults were vaccinated. A total of 92,711 report forms were received by the pharmacovigilance centre, and 12,695 subjects presented at least one adverse event. The most frequently involved systems/disorders were application site disorders (48.4%), whole-body general disorders (21.8%), central and peripheral nervous system disorders (14.6%), and gastrointestinal system disorders (4.7%). Most of these adverse events were transient and not serious. There were 13 serious adverse events: one each of syncope, fever, headache with fever, neuralgia, serum sickness, arthritis, purpura, facial paralysis, multiple sclerosis, lipoma, and meningism, and two cases of bronchospasm. No significant difference was found in rates of adverse event reports between both vaccines. The estimated incidence of serious adverse effect reports was 7 per 100,000. Conclusions: This campaign was the second immunisation campaign undertaken in France involving both physicians and families as reporters. Although unlabeled adverse effects were identified during this campaign, they were mostly nonserious and have been known to occur with other vaccines.
