Changing Trends of Invasive Pneumococcal Disease in the Era of Conjugate Pneumococcal Vaccination in Olmsted County: A Population-Based Study

Abstract

ObjectiveTo estimate the incidence of invasive pneumococcal disease (IPD) in the pre–13-valent pneumococcal conjugate vaccine (pre-PCV13; 7-valent pneumococcal conjugate vaccine era, 2002-2010) and post-PCV13 (2011-2018) time periods. Patients and MethodsUsing the Rochester Epidemiology Project, we conducted a population-based cohort study of all IPD cases in Olmsted County, Minnesota, from January 1, 2002, to December 31, 2018. ResultsOverall, 187 cases of IPD were identified. The incidence of IPD decreased significantly from 11.1 (95% CI, 9.1 to 13.2) to 5.6 (95% CI, 4.3 to 6.9) per 100,000 person-years when the pre- and post-PCV13 periods (2002-2010 vs 2011-2018) were compared (P<.001). Of the 187 patients with IPD, 112 (59.9%) had previously received at least 1 dose of pneumococcal vaccine. Among the IPD cases in the post-PCV13 period, there was an increase in non-PCV13 serotypes, mainly 11A (from 1.0% [1 of 105] to 6.2% [4 of 64]) and 33F (from 2.9% [3 of 105] to 15.6% [10 of 64]), while PCV13/non–7-valent pneumococcal conjugate vaccine serotypes declined from 38.1% (40 of 105) to 15.6% (10 of 64). At 30 days after an IPD diagnosis, the survival rate was 88.8% (95% CI, 84.4% to 93.4%). ConclusionA marked decline in IPD incidence occurred during the post-PCV13 era. Because of the observed increase in non-PCV13 serotypes, coupled with multiple factors that impact the epidemiology of IPD, ongoing surveillance of patients with IPD, particularly due to non-PCV13 serotypes, is warranted.