Human metapneumovirus pneumonia hits hardest in adults aged 80 and over

Adults aged 80 years and older who develop pneumonia from human metapneumovirus face substantially higher hospitalization rates and more severe clinical and radiologic features than younger adults, according to a retrospective single-center study of 106 patients published in BMC Infectious Diseases.

Human metapneumovirus is a significant viral pathogen associated with acute lower respiratory tract infections, particularly in elderly people, yet data on the clinical characteristics and outcomes of hMPV pneumonia among elderly people remain sparse. The researchers, led by Hyeon Hwa Kim and Yon Ju Ryu of Ewha Womans University Seoul Hospital, reviewed records from 106 adult patients with polymerase chain reaction-confirmed hMPV infection and radiologically confirmed pneumonia diagnosed at their hospital between September 2022 and March 2025.

The cohort had a median age of 71 years, and 37.8% of the patients were male. Hypertension was the most common comorbidity, present in 43.4% of patients, followed by malignancy and diabetes mellitus, each affecting 24.5%. To examine how age shaped the disease course, the patients were divided into two groups: those younger than 80 years, who numbered 79 and made up 74.5% of the cohort, and those aged 80 years or older, who numbered 27 and made up 25.5%.

The age-group comparisons revealed several significant differences. Patients aged 80 and older had a higher prevalence of hypertension, at 63.0% versus 36.7% in the younger group, and of dementia, at 22.2% versus 5.1%. Their chest imaging also showed more extensive disease, with multilobar involvement in 92.6% versus 74.7% and pleural effusion in 22.2% versus 3.8%. These differences in hypertension, dementia, multilobar involvement, and pleural effusion were all statistically significant.

Co-infection was a notable feature of the cohort. Additional microorganisms were detected in 32.1% of patients, and bacterial organisms alone were more common than viral organisms alone, at 24.5% versus 5.7%. Haemophilus influenzae and Klebsiella pneumoniae were the most frequently detected bacteria among the co-pathogens.

The overall hospitalization rate was 82.1%, and it was significantly higher among patients aged 80 and older, at 96.3% versus 77.2% in the younger group. Intensive care unit admission rates were numerically higher in the older group, at 25.9% versus 10.1%, although this difference did not reach statistical significance.

Within the hospitalized subgroup, the researchers performed a multivariable analysis to identify factors linked to length of stay. Greater initial oxygen requirement was associated with longer hospitalization, indicating that the degree of respiratory support needed at presentation tracked with how long patients remained in hospital.

The authors conclude that adults aged 80 years and older with hMPV pneumonia had higher hospitalization rates and more severe clinical and radiologic features in the age-group comparisons, and they highlight the substantial clinical burden of hMPV pneumonia in older adults and the importance of careful assessment of disease severity at presentation.

As a retrospective analysis of patients at a single hospital, the study describes associations observed in one cohort rather than causal effects, and the ICU admission finding did not reach statistical significance. The findings nonetheless add to the limited evidence base on hMPV pneumonia in the very old, a group in which the virus appears to impose a heavier clinical burden.

Subject of Research: Clinical characteristics and outcomes of human metapneumovirus pneumonia in adults aged 80 years and older

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

Article References: Kim, H. H., & Ryu, Y. J. (2026). Clinical characteristics and outcomes of human metapneumovirus pneumonia: focus on patients aged 80 years and older. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14724-2

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14724-2

Keywords: human metapneumovirus, pneumonia, elderly, hospitalization, respiratory infection, co-infection, ICU admission, radiology, retrospective study, BMC Infectious Diseases, Clinical, characteristics