New epidemiological characteristics of childhood IgA vasculitis in the post-COVID-19 era: a single-center retrospective cohort study.

Publication date: May 19, 2026

To compare hospitalization characteristics, clinical phenotypes, risk factors for IgA vasculitis nephritis (IgAVN), and prognostic outcomes in children with IgA vasculitis (IgAV) before and after the COVID-19, thereby elucidating the impact of the pandemic on the disease spectrum of IgAV to provide evidence for optimized disease management and precision medicine in the Post-COVID-19 era. A single-center retrospective cohort study was conducted involving children hospitalized with IgAV during two periods: Pre-COVID-19 (2017-2019) and the Post-COVID-19 endemic phase (2023-2025). We systematically compared general demographics, clinical phenotypes, and etiological profiles between the two cohorts. IgAV hospitalization proportions were calculated, and time-series models predicted crude hospitalization rates to assess burden trends. Furthermore, a 6-month follow-up was performed for newly-diagnosed non-nephritic patients to evaluate relapse rate and progression to IgAVN. Finally, multivariate logistic regression identified independent IgAVN risk factors. Compared to the Pre-COVID-19 period, patients in the Post-COVID-19 era exhibited significant alterations in humoral immunity and complement profiles, alongside increased rates of Mycoplasma pneumoniae infection. The disease burden intensified markedly: hospitalization duration, costs, and the proportion of IgAV admissions (including both newly-diagnosed and relapsed cases) surged, with the observed crude hospitalization rate significantly exceeding model predictions. Among newly-diagnosed cases, the proportion of the renal subtype increased significantly, while the cutaneous-only form decreased. Follow-up data revealed no significant difference in relapse rates between cohorts; However, the progression rate to nephritis was significantly elevated in the Post-COVID-19 group. Duration of rash emerged as the sole consistent independent predictor of IgAVN across both periods. In the post-COVID-19 era, childhood IgAV presents with new clinical characteristics, marked by an increased overall disease burden and a shift towards more severe clinical phenotypes. These changes may be associated with rising Mycoplasma pneumoniae infection and dysregulation of the complement-coagulation system. Notably, newly-diagnosed non-nephritic patients face a significantly higher risk of renal involvement, underscoring the need for enhanced early clinical monitoring and long-term follow-up. While the spectrum of risk factors for IgAVN has evolved, rash duration remains a critical predictor requiring close attention.

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