Comparison of human metapneumovirus and Respiratory Syncytial Virus in children with acute lower respiratory infections in Wenzhou, China from 2021 to 2022: a retrospective study

Objective To compare the clinical characteristics of human metapneumovirus (HMPV) and respiratory syncytial virus (RSV) infections in children hospitalized with acute lower respiratory infections (ALRI). Methods Children hospitalized with ALRI in Wenzhou, China from 2021 to 2022 were examined for HMPV and RSV in sputum or nasopharyngeal secretions by multiplex real-time quantitative polymerase chain reaction (PCR). Demographic data, clinical features, laboratory findings, and radiological characteristics were compared between HMPV group and RSV group. Results A total of 15,772 hospitalized children were screened and tested by multiplex PCR. 889 (5.6%) were HMPV-positive and 2,196 (13.9%) were RSV-positive. Compared with the RSV group, the HMPV group had a lower proportion of males (55.2% vs. 62.2%, P  = 0.002), an older median age (2.5 years vs. 1.6 years, P  < 0.001), and a higher proportion of underlying conditions (9.9% vs. 6.0%, P  = 0.001). The HMPV group exhibited significantly longer duration of fever ( P  < 0.001) and higher peak temperature ( P  < 0.001) compared to the RSV group. In contrast, the RSV group were more likely to present with respiratory distress, including intercostal or subcostal retractions ( P  = 0.006) and head bobbing respiration ( P  = 0.032). Significantly higher levels in the HMPV group for C-reactive protein (14.18 mg/L vs. 7.80 mg/L, P  < 0.001), neutrophil percentage (60.6% vs. 56.5%, P  = 0.007), procalcitonin ( P  = 0.001), and lactate dehydrogenase (422.0 U/L vs. 381.0 U/L, P  < 0.001) than the RSV group. HMPV-infected children were more likely to exhibit patchy or linear opacities (71.5% vs. 65.1%, P  = 0.016), pulmonary consolidation (4.1% vs. 2.1%, P  = 0.047), and atelectasis (1.8% vs. 0%, P  = 0.001) compared to the RSV-infected children. Conclusion In children hospitalized with ALRI, those infected with HMPV were more likely to be older, have underlying conditions, experience prolonged and higher-grade fever, demonstrate more pronounced systemic inflammatory responses, and prone to develop pulmonary consolidation and atelectasis compared with RSV-infected children.