Impact of PCV-13 vaccine on invasive pneumococcal disease in hospitalis children: A multi-institutional analysis

Aim We aimed to describe changes in invasive pneumococcal disease (IPD) hospitalisations after introduction of the pneumococcal conjugate vaccine (PCV13). Methods This was a retrospective analysis of the Pediatric Health Information System (PHIS) database, including children with IPD pre-PCV13 (2004-2009) and post-PCV13 (2012-2017). Healthy children and those with chronic conditions were analysed separately. The primary outcome was IPD incidence. Secondary outcomes included length of stay, intensive care unit (ICU) admission, mechanical ventilation and mortality. Results 9160 hospitalisations for IPD were included. The IPD rate per 100 000 discharges was 180 pre-PVC13 and 150 post-PCV13 [17% decrease (P = 0.085)]. The observed IPD rate in 2017 was 45.5% lower than the rate predicted by the pre-PCV13 trend (95% CI: 44%-46%). While a significant decrease in IPD (32%, P = 0.026) was observed among healthy children, there was no change in those with chronic conditions (9%, P = 0.24). In the post-PCV13 period, more IPD patients had chronic conditions, ICU admissions and longer ICU stays. Conclusion Although there was no overall reduction in IPD after PCV13, we observed a significant decrease in IPD among healthy patients. Further research is needed to elucidate microbiology or other factors contributing to persistent IPD hospitalisations.