Epidemiology of pediatric invasive pneumococcal disease in an inner-city tertiary care center: A 13-year study and post-pandemic insights

• Pediatric Invasive pneumococcal disease (IPD) remains a cause of morbidity. • Majority of patients with IPD and known immunization status were fully immunized. • The rise of IPD incidence caused by reduced vaccination and immunity debt. • Strengthening immunization programs and monitoring serotype trends are essential. Invasive pneumococcal disease (IPD) remains a significant cause of morbidity and mortality in children. While global IPD incidence declined during the COVID-19 pandemic due to mitigation measures, a resurgence followed the relaxation of these interventions. The primary objective is to describe the epidemiology of IPD at our institution after the introduction of PCV-13 and to compare trends before and after the COVID-19 pandemic. A retrospective chart review of IPD patients ≤21 years of age admitted between January 2010 - February 2024 at the Children’s Hospital of Michigan, Detroit. Patients were further categorized into 2 groups: pre-pandemic (2016-2020) and pandemic/post-pandemic (2020-2024). 143 cases were included. IPD incidence decreased during the pandemic (2020-2021) to 0.6-0.8 per 1000 hospital admissions but rebounded in 2022-2023 to 1.7-1.4 per 1,000 hospital admissions. Of 143 patients 99/143(69 %) had no known risk factor and 12/143 (8.3 %) had sickle cell disease. 73 % (90/143) were fully immunized. Pneumococcal antibodies were tested in 37 patients and 20/37(54 %) had low titers; 16/20 (80 %) were fully immunized. No statistically significant differences were observed between the two periods regarding age, gender, clinical presentation or clinical outcome ( p = >0.05). However, the proportion of unimmunized children was significantly higher in the post-pandemic period ( n = 8/43, 20.5 %) compared to pre-pandemic period ( n = 2/49, 4.8 %; p = 0.03). IPD incidence increased during the two years post COVID-19 pandemic, potentially due to decreased vaccination. Recognizing these epidemiological shifts and addressing vaccination gaps with use of updated vaccine are critical in preventing future IPD outbreaks.