Incidence of Meningococcal Disease Before and After Implementation of Quadrivalent Meningococcal Conjugate Vaccine in the United States.

Importance: In 2005, the US Advisory Committee on Immunization Practices recommended routine quadrivalent meningococcal conjugate (MenACWY) vaccine for all adolescents aged 11 to 12 years, and in 2010, a booster dose for adolescents aged 16 years. Measuring the association between MenACWY vaccination and the incidence of meningococcal disease in adolescents is critical for evaluating the adolescent vaccination program and informing future vaccine policy. Objective: To describe the association between MenACWY vaccination and the incidence of meningococcal disease in US adolescents. Design, Setting, and Participants: In this cohort study, analysis of surveillance data included all confirmed and probable cases of Neisseria meningitidis reported to the National Notifiable Diseases Surveillance System from January 1, 2000, to December 31, 2017. Statistical analysis was conducted from October 1, 2018, to August 31, 2019. Exposures: Routine MenACWY vaccination among US adolescents. Main Outcomes and Measures: Poisson segmented regression analysis was used to model the annual incidence of meningococcal disease among adolescents aged 11 to 15 years and 16 to 22 years before the introduction of the MenACWY vaccine (2000-2005), after the primary dose recommendation (2006-2010), and after the booster dose recommendation (2011-2017); 95% CIs were used to determine significant differences between time periods. Results: The national incidence of meningococcal disease declined from 0.61 cases per 100 000 population during the prevaccine period (2000-2005) to 0.15 cases per 100 000 population during the post-booster dose period (2011-2017). The greatest percentage decline was observed for serogroup C, W, and Y combined (CWY) among adolescents aged 11 to 15 years and 16 to 22 years in the periods after vaccine introduction. Incidence of serogroup CWY meningococcal disease among adolescents aged 11 to 15 years decreased by 16.3% (95% CI, 12.1%-20.3%) annually during the prevaccine period and 27.8% (95% CI, 20.6%-34.4%) during the post-primary dose period (P = .02); among adolescents aged 16 to 22 years, the incidence decreased by 10.6% (95% CI, 6.8%-14.3%) annually in the post-primary dose period and 35.6% (95% CI, 29.3%-41.0%) annually in the post-booster dose period (P < .001). An estimated 222 cases of meningococcal disease due to serogroup CWY among adolescents were averted through vaccination during the evaluation period. Conclusions and Relevance: After introduction of a primary and booster MenACWY dose, the rates of decline in incidence of meningococcal disease due to serogroup C, W, or Y accelerated nearly 2-fold to 3-fold in vaccinated adolescent age groups. Although the MenACWY vaccine alone cannot explain the decline of meningococcal disease in the United States, these data suggest that MenACWY vaccination is associated with reduced disease rates in adolescents.