Clinical characteristics and outcomes of human metapneumovirus pneumonia: focus on patients aged 80 years and older

Human metapneumovirus (hMPV) is a significant viral pathogen associated with acute lower respiratory tract infections, particularly in elderly people. However, data on the clinical characteristics and outcomes of hMPV pneumonia among elderly people remain sparse. We retrospectively reviewed data from 106 adult patients with polymerase chain reaction-confirmed hMPV infection and radiologically confirmed pneumonia diagnosed at Ewha Womans University Seoul Hospital between September 2022 and March 2025. Baseline characteristics, treatment, and clinical outcomes were analyzed by age group (< 80 vs. ≥80 years). The 106 patients had a median age of 71 years, and 37.8% of them were male. Hypertension (43.4%), malignancy (24.5%), and diabetes mellitus (24.5%) were the most common comorbidities. The patients were categorized into two age groups: <80 years ( n = 79, 74.5%) and ≥ 80 years ( n = 27, 25.5%). Patients aged ≥ 80 years had a significantly higher prevalence of hypertension (63.0% vs. 36.7%, p = 0.017), dementia (22.2% vs. 5.1%, p = 0.016), multilobar involvement (92.6% vs. 74.7%, p = 0.048), and pleural effusion (22.2% vs. 3.8%, p = 0.008). Additional microorganisms were detected in 32.1% of patients, with bacterial organisms alone (24.5%) being more common than viral organisms alone (5.7%); Haemophilus influenzae and Klebsiella pneumoniae were the most frequently detected bacteria. The overall hospitalization rate was 82.1% and was significantly higher among patients aged ≥ 80 years (96.3% vs. 77.2%, p = 0.038). ICU admission rates were numerically higher in patients aged ≥ 80 years (25.9% vs. 10.1%), although the difference was not statistically significant ( p = 0.150). In multivariable analysis among hospitalized patients, greater initial oxygen requirement was associated with longer hospitalization. Adults aged ≥ 80 years with hMPV pneumonia had higher hospitalization rates and more severe clinical and radiologic features in age-group comparisons. These findings highlight the substantial clinical burden of hMPV pneumonia in older adults and the importance of careful assessment of disease severity at presentation.