420 - Increasing Rates of Invasive Pneumococcal Disease in Children Vaccinated Against Streptococcus pneumoniae

Publication Number: 2408.420

Declan Quinn, University of Chicago, Elmhurst, IL, United States; Lilly H. Cheng-Immergluck, University of Chicago Vaccine Center of Excellence, Chicago, IL, United States; Mahima Sinha, University of Chicago Division of the Biological Sciences The Pritzker School of Medicine, Chicago, IL, United States; Angelica Moran, University of Chicago Division of the Biological Sciences The Pritzker School of Medicine, Chicago, IL, United States; Randee Estes, University of Chicago Division of the Biological Sciences The Pritzker School of Medicine, Chicago, IL, United States; Andrew Travis, University of Chicago Pritzker School of Medicine, Chicago, IL, United States; Sophie Ginsberg, University of Chicago, Chicago, IL, United States; Nathaniel Stuit, Comer Children's Hospital at University of Chicago Medical Center, Chicago, IL, United States; Sadia Firoza Chowdhury, Comer Children's Hospital at University of Chicago Medical Center, Chicago, IL, United States

Background: Streptococcus pneumoniae (SP) causes severe and invasive disease (pneumonia, meningitis, sepsis.) SP is the leading cause of bacterial pneumonia and pneumonia-related deaths in children < 5 years of age. Routine immunization with pneumococcal conjugated vaccines (PCV) has led to a decrease of infections. The CDC reports that there has been a 95% decrease in invasive Pneumococcal disease in children < 5 between the years 1998-2021, including a 99% decrease in disease caused by the serotypes covered in the PCV13 vaccine. Recently, we observed increasing trends of healthy children (≥5 years) developing serious/invasive pneumococcal disease (SIPD). There is currently no routine surveillance of IPD in this age group.

Objective: Identify and compare hospitalized children at an urban medical center with SIPD who are < 5 years to those ≥5 years during 3 periods: before/during/after the COVID-19 pandemic and determine their PCV vaccination rates.

Design/Methods: Retrospective data analysis of hospitalized children with SIPD from 1/2017 - 12/2024. Data was extracted from electronic health records; with a subset of SP isolates available for molecular testing (1/2023-1/2025). Population characteristics and risk factors, including age, race, sex, and insurance status between the two age groups will be compared, as well as molecular characterization of the isolates (serotyping and whole genomic sequencing). Pneumococcal immunization status will be compared after the molecular characterization of the isolates.

Results: Between the years 2017 and 2024 there were a total of 101 IPD cases at the medical center. Of the 101 cases, there were 46 pediatric admissions for IPD, and 18 (39%) were ≥5 years old. Prior to the COVID-19 pandemic a majority of IPD cases did not require hospital admission, however this trend reversed post-pandemic. The most common IPD diagnosis was sepsis due to Streptococcus pneumoniae (52%), followed by pneumonia and meningitis. Levels of admissions spiked after the pandemic, from 9 total admissions in 2020-2022 to 14 admissions in 2023 alone.

Conclusion(s): There is a significant prevalence of children older than 5 years of age who received PCV13 and suffer from SIPD. The rates and severity of infections are similar to those < 5 years. The persistent rise of SIPD in children highlights the need for ongoing surveillance and perhaps updated vaccination recommendations to address those older children with SIPD.

Number of Admitted Patients (2017-2024)
Number of admitted patients by year split into the two age groups ( <5 and 5-18)

Nan-Admitted vs. Admitted Patients (2017-2024)
Number of IPD cases that required hospital admission versus those that did not result in a hospital admission

Diagnoses of Admitted Patients
Breakdown of admitted patients diagnoses (sepsis, meningitis, and pneumonia due to Streptococcus pneumoniae)