Background Both pathogenic bacteria and viruses are frequently detected in the nasopharynx (NP) of children in the absence of acute respiratory infection (ARI) symptoms. The aim of this study was to estimate the aetiological fractions for ARI hospitalisation in children for respiratory syncytial virus (RSV) and influenza virus and to determine whether detection of specific respiratory pathogens on NP samples was associated with ARI hospitalisation. Methods 349 children up to 5 years of age hospitalised for ARI (following a symptom-based case definition) and 306 hospital controls were prospectively enrolled in 16 centres across seven European Union countries between 2016 and 2019. Admission day NP swabs were analysed by multiplex PCR for 25 targets. Results RSV was the leading single cause of ARI hospitalisations, with an overall population attributable fraction (PAF) of 33.4% and high seasonality as well as preponderance in younger children. Detection of RSV on NP swabs was strongly associated with ARI hospitalisation (OR adjusted for age and season: 20.6, 95% CI: 9.4 to 45.3). Detection of three other viral pathogens showed strong associations with ARI hospitalisation: influenza viruses had an adjusted OR of 6.1 (95% CI: 2.5 to 14.9), parainfluenza viruses (PIVs) an adjusted OR of 4.6 (95% CI: 1.8 to 11.3) and metapneumoviruses an adjusted OR of 4.5 (95% CI: 1.3 to 16.1). Influenza viruses had a PAF of 7.9%, PIVs of 6.5% and metapneumoviruses of 3.0%. In contrast, most other pathogens were found in similar proportions in cases and controls, including Streptococcus pneumoniae , which was weakly associated with case status, and endemic coronaviruses. Conclusion RSV is the predominant cause of ARI hospitalisations in young children in Europe and its detection, as well as detection of influenza virus, PIV or metapneumovirus, on NP swabs can establish aetiology with high probability. PAFs for RSV and influenza virus are highly seasonal and age dependent. The datasets generated and analysed for this report are available from the corresponding author upon reasonable request.

中文翻译：

---

欧洲需要住院治疗的学龄前儿童急性呼吸道感染的病因——来自 PED-MERMAIDS 多中心病例对照研究的结果

背景 在没有急性呼吸道感染 (ARI) 症状的儿童的鼻咽 (NP) 中经常检测到致病细菌和病毒。本研究的目的是估计呼吸道合胞病毒 (RSV) 和流感病毒导致儿童 ARI 住院的病因学分数，并确定在 NP 样本上检测到特定呼吸道病原体是否与 ARI 住院有关。方法 2016 年至 2019 年间，在 7 个欧盟国家的 16 个中心前瞻性招募了 349 名因 ARI 住院的 5 岁以下儿童（遵循基于症状的病例定义）和 306 名医院对照。通过多重 PCR 分析入院日 NP 拭子25 个目标。结果 RSV 是 ARI 住院的主要原因，总人口归因分数 (PAF) 为 33.4%，季节性强，年龄较小的儿童占优势。在 NP 拭子上检测到 RSV 与 ARI 住院密切相关（根据年龄和季节调整的 OR：20.6，95% CI：9.4 至 45.3）。其他三种病毒病原体的检测显示出与 ARI 住院密切相关：流感病毒的调整后 OR 为 6.1（95% CI：2.5 至 14.9），副流感病毒（PIV）的调整后 OR 为 4.6（95% CI：1.8 至 11.3）和偏肺病毒调整后的 OR 为 4.5（95% CI：1.3 至 16.1）。流感病毒的 PAF 为 7.9%，PIV 为 6.5%，偏肺病毒为 3.0%。相比之下，大多数其他病原体在病例和对照中的发现比例相似，包括与病例状态弱相关的肺炎链球菌和地方性冠状病毒。结论 RSV 是欧洲幼儿 ARI 住院的主要原因，其检测与流感病毒、PIV 或偏肺病毒检测一样，鼻咽拭子检测可以确定病因的概率较高。RSV 和流感病毒的 PAF 具有高度的季节性和年龄依赖性。本报告生成和分析的数据集可根据合理要求从相应的作者处获得。