Comparative Analysis of hMPV, RSV, and Influenza in Adults Hospitalized with ILI

Overview

This study compared human metapneumovirus (hMPV) infections with influenza A/B (FLUV) and respiratory syncytial virus (RSV) infections in adults hospitalized for influenza-like illness (ILI) in France from 2012 to 2022. hMPV infections were less frequent but associated with higher rates of complications, especially acute heart failure, compared to influenza, with similar complication rates to RSV. Mortality rates were comparable across all three viral infections.

Background

Human metapneumovirus (hMPV) is an important respiratory pathogen affecting individuals of all ages, particularly older adults with chronic conditions. It can cause a spectrum of illness from mild upper respiratory symptoms to severe pneumonia. Despite its clinical significance, data on hMPV frequency and outcomes in older hospitalized adults remain limited due to underdiagnosis and variable testing practices. With antiviral therapies and vaccines for hMPV in development, understanding patient characteristics and clinical outcomes is critical.

Data Highlights

Key Findings

• Among 6618 adults hospitalized with ILI, 55% tested positive for at least one respiratory virus; FLUV was most common (42%), followed by RSV (7%) and hMPV (5%).
• hMPV+ patients were significantly more likely to develop at least one complication during hospitalization compared to FLUV+ patients (60% vs 50%, P = .02).
• Acute heart failure occurred twice as often in hMPV+ patients compared to FLUV+ patients (22% vs 11%, P < .001).
• Rates of respiratory and cardiac complications were similar between hMPV+ and RSV+ patients.
• In-hospital all-cause mortality rates were similar across hMPV+, FLUV+, and RSV+ groups (4%, 4%, and 5%, respectively).
• hMPV infections predominantly affected older adults with multiple chronic conditions.

Clinical Implications

Clinicians should recognize that hMPV infection in hospitalized adults with ILI is associated with a higher risk of complications, particularly acute heart failure, compared to influenza. Given the similar severity profile to RSV, hMPV should be considered in differential diagnosis and management, especially in older patients with comorbidities. Enhanced diagnostic testing for hMPV may improve patient care and inform emerging antiviral and vaccine strategies.

Conclusion

Hospitalized adults with hMPV infection represent a vulnerable population with frequent cardiac and pulmonary complications, underscoring the need for heightened clinical awareness and targeted preventive measures. Outcomes are comparable to RSV and more severe than influenza in terms of complication rates.

References

1. FLUVAC Study Group 2012-2022 -- Comparative Analysis of hMPV, RSV, and Influenza Infections in Adults with ILI