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

To compare the clinical characteristics of human metapneumovirus (HMPV) and respiratory syncytial virus (RSV) infections in children hospitalized with acute lower respiratory infections (ALRI). Children hospitalized with ALRI in Wenzhou, China from 2021 to 2022 were detected for HMPV and RSV in sputum or nasopharyngeal secretions by multiplex reverse transcription polymerase chain reaction (RT-PCR). A comparative analysis of demographic, clinical, laboratory, and radiological characteristics was performed retrospectively for patients in the HMPV and RSV groups. A total of 15,772 hospitalized children were screened and tested by multiplex RT-PCR. 889 (5.6%) were HMPV-positive and 2,196 (13.9%) were RSV-positive. Compared with the RSV-associated ALRI group, the HMPV-associated ALRI group exhibited 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 medical 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 with the RSV group. In contrast, the RSV group were more likely to present with respiratory distress, including retractions ( P = 0.006) and nodding breathing ( P = 0.032). Levels of C-reactive protein (14.18 mg/L vs. 7.80 mg/L, P < 0.001), procalcitonin ( P = 0.001), lactate dehydrogenase (422.0 U/L vs. 381.0 U/L, P < 0.001), and neutrophil percentage (60.6% vs. 56.5%, P = 0.007) in the HMPV group were significantly higher than the RSV group. Children with HMPV-associated ALRI 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 with those in the RSV group. In hospitalized children, those with HMPV infection may be more common in older children and more likely to have underlying medical conditions than those with RSV infection. Children with HMPV-associated ALRI may present with prolonged, higher-grade fever, more pronounced systemic inflammatory responses, and an increased risk of developing pulmonary consolidation and atelectasis.