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.

Neisseria meningitidis carriage during an outbreak of serogroup C disease.

During 2001, an outbreak of serogroup C meningococcal disease led to immunization of individuals aged 13-29 years in Abbotsford, British Columbia, Canada. This study addresses the distribution of Neisseria meningitidis carriage in this population and the implications of that distribution for the targeting of the immunization campaign. Pharyngeal swabs were obtained at immunization from 2004 people. Colonies were identified and serogrouped using standard agglutination methods and by PCR. Isolates were characterized using pulsed-field gel electrophoresis (PFGE). The prevalence of N. meningitidis carriage was 153 carriers per 2004 subjects (7.6%; 95% confidence interval, 6.5%-8.9%). Only 6 (4%) of the isolates from these carriers were found to be serogroup C by agglutination or PCR testing, and all of these were from individuals within the age group targeted for immunization. Only 1 of these 6 isolates was found to be identical to the outbreak strain by PFGE. The observation that a virulent strain is not circulating widely suggests the possibility of low background immunity in the population at risk and emphasizes the importance of vaccination in controlling epidemic group C meningococcal disease.