Meningococcal control in the United States and Africa.

(See the articles by Mueller et al. and by Vu et al., on pages 812–20 and 821–8, respectively.) It is estimated that there are 1400–2800 cases of invasive meningococcal infections each year in the United States, and sero-groups B, C, and Y cause approximately one-third of the cases each [1]. The highest age-specific incidence occurs in young children, but a secondary peak is seen in adolescents [2]. Furthermore, morbidity and mortality caused by meningococcus are higher in older children than in younger children [3, 4]. College freshmen, especially those living in dormitories, have an increased incidence of systemic meningococcal infections, most of which are caused by serogroup C [5]. The Centers for Disease Control and Prevention and the American Academy of Pediatrics recommend that the quadriva-lent meningococcal polysaccharide vaccine (MPSV-4) be provided for these college students , to decrease their risk of developing meningococcal disease [6]. The length of protection after MPSV-4 administration has been debated, but 3–5 years is the general estimate. The first meningococcal conjugate vaccine (meningococcal polysaccharide–diph-theria toxoid conjugate vaccine [containing serogroup A, C, W-135, and Y polysaccha-rides]; MCV-4) was licensed in the United States in January 2005, on the basis of serum bactericidal antibody (SBA) titers for recipients of MCV-4 that were not inferior to those for recipients of the previously licensed MPSV-4 vaccine. Subsequently, MCV-4 was recommended for routine administration to children starting at age 11– 12 years, and a catch-up strategy was suggested for 15-year-olds or those entering high school [1, 7]. How long protection will persist after MCV-4 administration is also unknown, but in this issue of the Journal of Infectious Diseases, Vu et al. [8] have extended the findings previously reported from a 3-year follow-up study of adolescents who received MCV-4, MPSV-4, or no meningo-coccal vaccine [9]. These investigators used a convenience sample of adolescents who were an average of 14 years old at the time of vaccination and for whom adequate serum samples were available 3 years later. Vu et al. confirmed that the concentrations of antibodies to the capsules of serogroups C, W-135, and Y were equivalent in children vaccinated with either MCV-4 or MPSV-4, and both were significantly higher than those in unvaccinated adolescents of the same age. Furthermore, when an SBA assay with human complement (as opposed to rabbit complement) was used, a significantly greater proportion of adolescents vaccinated with either MCV-4 or MPSV-4 had an SBA titer …