High prevalence and clinical impact of microbial co-detection in hospitalized children with human parainfluenza virus type 1.

Human parainfluenza virus type 1 (HPIV-1) is an important but underrecognized pathogen associated with acute respiratory infections (ARI) in children, although its clinical impact remains poorly defined, particularly with microbial co-detection. This study enrolled hospitalized children with ARI who underwent targeted next-generation sequencing (tNGS). Clinical features were compared between HPIV-1 mono-detection and co-detection groups, as well as between patients with severe and non-severe pneumonia. Among 9,394 enrolled children, HPIV-1 was detected in 1.7%, predominantly in those aged 6 months to 2 years. Co-detection with other respiratory pathogens was observed in 95.7% of HPIV-1-positive cases, with viral-bacterial co-infection being the most common pattern. IMPORTANCE: Human parainfluenza virus type 1 (HPIV-1) is an underrecognized contributor to pediatric acute respiratory infections (ARI), yet its clinical impact remains unclear, particularly regarding co-detection with other microbes. Based on targeted next-generation sequencing (tNGS), this study demonstrates that HPIV-1 detection in hospitalized children with ARI is characterized by a high rate of microbial co-detection, which is associated with greater disease severity. Elevated inflammatory markers (procalcitonin [PCT] and erythrocyte sedimentation rate [ESR]), prolonged fever, complication occurrence, and need for respiratory support serve as key predictors of progression to severe pneumonia in these children. These findings offer important clinical evidence to support the development of a predictive model for severe pneumonia in HPIV-1-positive children and provide valuable guidance for optimizing diagnostic and therapeutic strategies for HPIV-1-associated respiratory infections.