Background: Conjugate meningococcal vaccines may decrease the incidence of disease. The staggered implementation of universal childhood meningococcal C conjugate (MenC) immunization programs across Canada offers an opportunity to evaluate the influence of these programs.
Methods: From 2002 to 2006, we conducted active, population-based surveillance for adult and pediatric hospital admissions related to meningococcal infections at the 12 centers of the Canadian Immunization Monitoring Program, Active (IMPACT), in collaboration with local public health officials.
Results: A total of 376 cases were reported during the 5 years of surveillance. Yearly totals were as follows: 96 in 2002, 73 in 2003, 81 in 2004, 58 in 2005, and 68 in 2006. Case fatality was 9.3% and adults had a significantly higher case fatality rate than children.
Average incidence per 100,000 was 0.62 (95% confidence interval [CI]: 0.50–0.76) in 2002 and 0.42 (95% CI: 0.32–0.53) in 2006. The highest rates were in children age 0 to 4 years, followed by adolescents age 15 to 19 years. Incidence of group C disease decreased significantly during the 5 years from 0.23 (95% CI: 0.16–0.32) in 2002 to 0.08 (95% CI: 0.04–0.14) in 2006, whereas incidence remained stable for groups B, Y, and W135. The decrease in group C disease was seen in provinces that first implemented MenC immunization programs.
Conclusions: A substantial decrease in group C incidence occurred in provinces with early MenC immunization programs. Serogroup C incidence remained stable in provinces without MenC programs. We found no evidence of serogroup replacement.