- D3.531 - Diverse Infectious Disease Outcomes After SARS CoV 2 Infection in Children and Adolescents: A Nationwide Matched Cohort Study

The COVID-19 pandemic and subsequent relaxation of non-pharmaceutical interventions reshaped pediatric infectious disease epidemiology. Beyond changes in exposure, prior SARS-CoV-2 infection may alter children’s susceptibility to subsequent infections. We compared infectious disease–related healthcare utilization between pediatrics with and without SARS-CoV-2 infection to evaluate whether prior COVID-19 is associated with increased susceptibility to diverse infectious diseases.

Using nationwide claims data from the Korean Health Insurance Review and Assessment Service covering the period from March 2020 through October 2022, we conducted a nationwide matched cohort study of children and adolescents aged 0–18 years. Children and adolescents with a documented SARS-CoV-2 infection were matched 1:1 to uninfected children and adolescents on age, sex, and index date. Analyses were performed for the main study period from March 2020 through March 2022, as well as for a subsequent period following widespread relaxation of non-pharmaceutical interventions, spanning April through October 2022. Changes in infectious disease–related healthcare utilization from the pre- to post-index period were compared between infected and uninfected children and adolescents using a difference-in-differences approach with negative binomial regression. P values were adjusted for multiple comparisons using the false discovery rate.

Compared with matched uninfected children and adolescents, those with SARS-CoV-2 infection showed significantly greater relative increases in healthcare utilization for respiratory infections, including upper respiratory tract infections (+49.4%), lower respiratory tract infections (+60.4%), and pneumonia (+34.2%). In contrast, non-respiratory infectious diseases demonstrated heterogeneous patterns, with a relative reduction in Kawasaki disease (−32.8%) and no significant differential change in gastrointestinal infections (+6.6%). For pathogen-specific respiratory infections, differential relative increases were observed for influenza (+2393.9%), Mycoplasma pneumoniae (+27.8%), adenovirus (+81.1%), and Haemophilus influenzae (+28.0%). These relative differences persisted in analyses conducted during the subsequent period following widespread relaxation of non-pharmaceutical interventions, with larger relative increases observed for upper and lower respiratory tract infections and pneumonia.

This nationwide matched cohort study demonstrates that prior SARS-CoV-2 infection is associated with pathogen- and disease-specific differences in infectious disease–related healthcare utilization among children and adolescents. These findings suggest that SARS-CoV-2 infection history contributes to heterogeneity in post-pandemic pediatric infectious disease burden and underscore the importance of incorporating prior infection status into pediatric infectious disease surveillance, risk stratification, and healthcare resource planning at the population level.