Association between chest CT features and disease severity in children with human bocavirus mono-infection: a retrospective cohort study

Human bocavirus (HBoV) is an established cause of pediatric lower respiratory tract infection, but the clinical relevance of chest CT findings in HBoV mono-infection remains uncertain. We retrospectively studied hospitalized children (< 18 years) with PCR-confirmed HBoV mono-infection and LRTI between September 2022 and December 2023. Disease severity was classified as moderate, severe, or critical. Chest CT images were independently reviewed by two blinded pediatric radiologists. Associations between imaging findings and critical disease were evaluated using logistic regression. Viral genomic analysis was performed in a subset of patients. A total of 194 children were included, including 124 (63.9%) moderate, 46 (23.7%) severe, and 24 (12.4%) critical cases. GGO was the most common CT finding across all severity groups (> 90%) and showed no association with critical disease. In contrast, uneven lung inflation increased stepwise with severity (moderate, 24.2%; severe, 54.3%; critical, 66.7%; P < 0.001). Both uneven lung inflation and atelectasis were independently associated with critical illness after adjustment for age and sex (uneven lung inflation: adjusted OR, 3.74; 95% CI, 1.53–9.82; P = 0.005; atelectasis: adjusted OR, 3.51; 95% CI, 0.99–11.08; P = 0.038). Kaplan–Meier analysis further showed that uneven lung inflation was associated with longer hospitalization (log-rank P = 0.048), while atelectasis showed a similar but non-significant trend. In children with PCR-confirmed HBoV mono-infection, GGO was consistently observed across all severity groups and showed no association with critical disease. In contrast, imaging features reflecting ventilation heterogeneity, particularly uneven lung inflation and atelectasis, were independently associated with critical illness after adjustment for age and sex. Kaplan–Meier analysis further demonstrated that uneven lung inflation was associated with prolonged hospitalization, with a similar but non-significant trend observed for atelectasis.