Solicited adverse events after influenza immunization among infants, toddlers, and their household contacts.

Objectives: We assessed adverse events, including oculorespiratory syndrome, following influenza immunization during the first year of a publicly-funded program for infants, toddlers and their household members in Canada.

Methods: Parents bringing infants and toddlers for influenza immunization to clinics in Quebec or British Columbia consented to structured telephone interview 5 to 10 days later. One adult provided information for all household members. Symptom experience commencing before and after immunization was assessed. Non-immunized persons also served as a comparison group for immunized household members.

Results: Sample included 690 immunized infants and toddlers and 1801 household members, 1374 immunized. Only fussiness, fever, decreased appetite, drowsiness, and nasal congestion/coryza were reported for >5% of infants/ toddlers within 72 hours of immunization, but only arm discomfort was reported among >5% of immunized household contacts. In multivariate analysis, muscle ache was the only systemic symptom reported more often by immunized household members compared to non-immunized persons. Oculorespiratory symptoms were infrequent and there was no difference between immunized and non-immunized household members in their report. Less than 1% of adults required time off work because of adverse events following influenza immunization in the household. Less than 2% of subjects experiencing an adverse event following influenza immunization were considered unlikely to be vaccinated again.

Conclusion: Influenza vaccine is well-tolerated by infants, toddlers and their household members. Post-marketing observational designs are an expedient way to assess adverse events following influenza immunization. These methods should be established and rehearsed annually in preparation for a pandemic.