Abstract: Objective　To describe epidemiologic and clinical changes in human parainfluenza virus（HPIV） infection among hospitalized children before，during，and after the COVID-19 pandemic（2016—2019，2020—2022，and 2023—2025），and to analyze host risk factors for severe pneumonia among children hospitalized with single HPIV infection. Methods　We retrospectively reviewed clinical data of children hospitalized with acute respiratory tract infection（ARTI） who underwent respiratory virus nucleic acid testing at the Children’s Hospital of Soochow University from January 2016 to August 2025. Results　The HPIV positivity rate was 3.07%-3.61% in 2016—2019，which increased to 4.08%-10.57% in 2020—2022，and further rose to 7.21%-12.25% in 2023—2025. The peak gradually shifted from spring to autumn and summer，The higher rates in 2016—2019 were observed in children<2 years of age（1-2 years：4.56%；<1 year：4.22%），whereas rates were lower in preschool and school-age/adolescent groups. In the post-pandemic period，positivity rates increased across all age groups<6 years，with the preschool group reaching the highest rate in 2025（19.09%）. Among HPIV-positive cases，1，426（25.43%） had at least one additional respiratory virus detected，with human rhinovirus，bocavirus，and respiratory syncytial virus being most common. In the single-HPIV hospitalization cohort，fever was more frequent during and after the pandemic；upper respiratory symptoms increased，while wheeze-related manifestations decreased. Prematurity（adjusted OR=3.28，95%CI 1.51-7.13） and chronic underlying diseases（adjusted OR=8.24，95%CI 3.90-17.38） were independent risk factors for severe pneumonia，whereas age<3 years （adjusted OR=0.90，95%CI 0.39-2.08） and pandemic period were not significantly associated with the risk of severe diseases. Conclusion　After the COVID-19 pandemic，HPIV positivity rate increases among hospitalized children，accompanied by seasonal peaks and the affected age distribution shifting toward later months and older age groups. However，overall disease severity does not markedly worsen among hospitalized children with single HPIV infection. The risk of severe pneumonia is primarily related to prematurity and chronic underlying disease.

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摘要： 目的　描述新型冠状病毒感染（COVID-19）大流行前期（2016—2019年）、期间（2020—2022年）及后期（2023—2025年）儿童人副流感病毒（human parainfluenza virus，HPIV）感染的流行病学和临床特征变化特点，并分析单一HPIV阳性住院患儿重症肺炎的宿主危险因素。方法　回顾性分析2016年1月至2025年8月在苏州大学附属儿童医院行呼吸道病毒核酸检测的急性呼吸道感染（acute respiratory tract infection，ARTI）住院患儿的临床资料。结果　2016—2019年HPIV阳性检出率为3.07%~3.61%；2020—2022年为4.08%~10.57%；2023—2025年升至7.21%~12.25%；流行高峰由春季渐次后移至秋季、夏季。大流行前期婴儿组与幼儿组检出率较高（1~<3岁：4.56%；<1岁：4.22%），而学龄前及学龄/青少年组较低；后期6岁以下各年龄组检出率总体上升，2025年学龄前组检出率最高（19.09%）。HPIV阳性病例中，合并检出其他呼吸道病毒1 426例（25.43%），以人鼻病毒、博卡病毒及呼吸道合胞病毒最常见。单一HPIV住院队列中，大流行期间及后期发热更为常见，上呼吸道症状比例升高，喘鸣相关表现减少。早产（调整后OR值=3.28，95%CI 1.51~7.13）与慢性基础疾病（调整后OR值=8.24，95%CI 3.90~17.38）为重症肺炎独立危险因素；年龄<3岁（调整后OR值=0.90，95%CI 0.39~2.08）及流行阶段与重症风险无显著关联。结论　COVID-19大流行后期，儿童住院人群中HPIV阳性检出率升高，季节高峰与感染年龄向更晚月份及更大年龄段迁移；但单一HPIV住院患儿的整体病程严重程度未见明显加重。重症肺炎风险主要与早产及慢性基础疾病相关。

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