A71-08 Clinical Severity and Risk Factors in Adult Human Metapneumovirus and Respiratory Syncytial Virus Infections: A Real-World Comparative Study

Background and Aims

Human metapneumovirus (hMPV) and respiratory syncytial virus (RSV) are increasingly recognized as important respiratory pathogens in adults; however, yet direct real-world comparisons of disease severity and outcomes remain limited. Clarifying clinical differences and shared risk factors for severe disease is essential for optimizing management strategies in adult populations. This study aimed to compare clinical characteristics, disease severity, and risk factors between adult patients with hMPV and RSV infection.

Methods

We conducted a retrospective observational study at the University of the Ryukyus Hospital. Adults aged ≥18 years with respiratory symptoms and laboratory-confirmed hMPV or RSV detected by multiplex polymerase chain reaction using nasopharyngeal swabs between April 2023 and December 2025 were included. Patients receiving long-term home oxygen therapy or those with a tracheostomy were excluded. Patient characteristics, hospitalization rates, and requirements for oxygen supplementation were compared between the virus groups. Logistic regression analysis was performed to identify independent risk factors for severe viral infection requiring oxygen supplementation, using clinically relevant variables.

Results

A total of 96 patients were analyzed (median age 64 years; 46.9% male), including 52 with hMPV and 44 with RSV. Baseline comorbidities, including hypertension, bronchial asthma, and malignancy, were similar between groups. Male sex were more frequent in hMPV group (62% vs 30%), while systemic corticosteroid use was more common among patients with RSV infection (8% vs 30%). Overall, 64% of patients were hospitalized and 53% required supplemental oxygen, with no significant differences between virus groups. Hospitalized patients tended to be older and had higher prevalences of chronic obstructive pulmonary disease, hypertension, heart failure, and chronic kidney disease. Virus-associated deaths occurred in three patients with hMPV infection and in none with RSV infection; all fatal hMPV cases involved concurrent viral co-infections, including SARS-CoV-2 (n = 2) and parainfluenza virus (n = 1). In multivariate analysis, cardiovascular disease was an independently associated with severe viral infection requiring oxygen supplementation (odds ratio 12.34, 95% confidence interval 1.30-117.13).

Conclusion

In adults, hMPV and RSV infections were associated with comparable disease severity, with high hospitalization rates reflecting a substantial burden of illness. Cardiovascular disease and the presence of viral co-infection emerged as key factors associated with severe and fatal outcomes underscoring the need for careful risk stratification and clinical vigilance in adult patients with respiratory viral infections.

This abstract is funded by: None