EpiReview: Meningococcal disease in NSW, 1991-2011: trends in relation to meningococcal C vaccination.

Aim: To review the epidemiology of invasive meningococcal disease in NSW for the period 1991-2011, in particular since the introduction of the meningococcal C vaccination program in 2003.

Methods: We undertook a descriptive analysis of NSW notifications of invasive meningococcal disease for the period 2003-2011, and explored long-term changes in the epidemiology of invasive meningococcal disease over the period 1991-2011.

Results: In the period 2003-2011, there were 1009 notifications of invasive meningococcal disease in NSW, an average annual rate of 1.6 per 100000 population. Notification rates were highest in the 0-4 and 15-19-year age groups (8.5 and 3.6 per 100000 population respectively). In the period 1991-2011, invasive meningococcal disease notifications increased between 1991 and 2000, peaking at 3.8 notifications per 100000 population in 2000. Notifications have decreased since that time to 1.0 per 100000 population in 2011, most markedly for serogroup C disease since the introduction of the meningococcal C vaccination program in 2003. Meningococcal C notifications reduced from 54 in 2002 (0.8 per 100000 population) to two in 2011 (0.03 per 100000 population). Meningococcal C deaths have also decreased, from nine in 2002 to zero in 2011. The greatest reduction in meningococcal C notifications has been in those aged 1-19 years, the target group for the vaccination program. Meningococcal B notifications have also decreased over the study period, however serogroup B remains the predominant serogroup for invasive meningococcal disease in NSW.

Conclusion: Notification rates of invasive meningococcal disease have decreased in NSW since 2000. Rates of serogroup C disease have decreased since the introduction of the meningococcal C vaccination program in 2003. Most of the burden of invasive meningococcal disease in NSW is now due to serogroup B disease.