Epidemiology of meningococcal disease in California, 2001-2007

Learning Objectives for this Presentation:
By the end of this presentation participants will be able to describe the epidemiology of meningococcal disease in California before and after the licensure of quadrivalent meningococcal conjugate vaccine (MCV4).

Background:
MCV4 was licensed in the United States in January 2005 for individuals aged 11-55 years. In May 2005, the ACIP recommended MCV4 for certain subgroups primarily during adolescence and in June 2007 revised the recommendations to include routine vaccination of all persons aged 11-18 years. In October 2007, licensure was expanded to include children aged 2-10 years.

Objectives:
To describe meningococcal disease epidemiology in California.

Methods:
We analyzed surveillance data in California from July 2001-June 2007, examining rates of meningococcal disease and death by age and serogroup both before and after the licensure of MCV4. We consider the time period of July 2001-June 2005 to be “pre-MCV4” and July 2005-June 2007 to be “post-MCV4”.

Results:
1129 cases of meningococcal disease were reported during the study period for overall incidence and mortality rates of 0.52 cases and 0.049 deaths per 100,000 population. Rates were highest for infants under 1 year and for adults 65 years and older. Of the 900 cases with serogroup information, 460 (51.1%) were a vaccine-preventable serogroup and 423 (47.0%) were serogroup B. Overall incidence declined pre-MCV4 to post-MCV4 from 0.55 to 0.46 cases per 100,000 population and declined across all age groups except adults 65 years and older. Mortality rates declined overall from 0.058 to 0.032 and from 0.032 to 0.018 per 100,000 population in vaccine-preventable serogroups. Serogroup-specific trends were difficult to interpret because serogroup identification improved over this time period and earlier data were incomplete.

Conclusions:
The overall incidence and mortality rates of meningococcal disease have declined since the licensure of MCV4. This analysis provides good baseline data for comparison of future trends of disease as vaccine uptake increases.