ABSTRACT
BACKGROUND: The 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in 2010 in the U.S. and its impact on pneumococcal meningitis (PM) is unknown. We assessed the impact of PCV13 on PM hospitalization rates 4years after the vaccine was introduced. METHODS: This was a retrospective analysis of the National Inpatient Sample from 2008-2014. Patients with an ICD-9-CM code for PM (320.1) were identified and rates calculated using US Census data as the denominator. Data weights were used to derive national estimates. We examined three time periods: 2008-2009 (late post-PCV7), 2010 (transition year), and 2011-2014 (post-PCV13). RESULTS: During the study period, there were 10,493 hospitalizations due to PM in the U.S. Overall, PM incidence decreased from 0.62 to 0.38 cases per 100,000 over this time (39% decrease; P<0.01). Among children <2years, the average annualized PM rate decreased by 45% from 2.19 to 1.20 per 100,000 (P=0.10). Annual PM rates decreased in those aged 18-39years (0.25-0.15 cases per 100,000; P=0.02) and 40-64years (0.95-0.54 cases per 100,000; P=0.03). A total of 1016 deaths were due to PM, and the case fatality rate was variable over the study period (8.3%-11.2%; P=0.96). CONCLUSION: Following the introduction of PCV13, hospitalization rates for PM decreased significantly with no subsequent improvements in case-fatality rate.