Reduction in invasive meningococcal disease in Queensland: a success for immunisation.

Since 2003, the Australian government has funded a conjugate serogroup C meningococcal vaccine for those aged over 1 year and born since 1 January 1984. This summary of the epidemiology of invasive meningococcal disease (IMD) in Queensland assesses the effect that the vaccination program has had on IMD notifications. In Queensland, IMD cases are notified to the Notifiable Conditions System by clinicians and laboratories. Additional surveillance data are collected by population health units from relatives of the case, the case and medical practitioners. In 2005, Queensland recorded its lowest number of cases and lowest incidence of IMD since statewide surveillance began. This remained low in 2006. The serogroup C rate in Queensland also declined to its lowest in 2006. The pattern of age specific incidence remains similar, though rates are lower in all but those aged less than 12 months. However, Indigenous rates are still twice non-Indigenous rates. The case fatality rate for IMD (all serogroups) has declined, possibly due to the reduced incidence of serogroup C and septicaemia cases. The program appears to have mostly achieved its aims of: reducing illness and death in the population at highest risk; inducing immunity in those who are vaccinated; and reducing the incidence of disease. However, there is considerable natural fluctuation in the rates of IMD and continued surveillance will be needed to monitor trends.