Abstract Background Human metapneumovirus (hMPV) and respiratory syncytial virus (RSV) are among the leading causes of acute respiratory infection. We evaluated the risk of severe outcomes in adults hospitalized with hMPV compared to RSV at Kaiser Permanente Southern California. Methods We performed a retrospective cohort analysis in adults aged ≥18 years who tested positive for hMPV or RSV from 7 days prior to 2 days after the date of hospital admission between 2011 and 2024. Outcomes included length of hospital stay, intensive care unit (ICU) admission, occurrence of complications, readmission, and mortality. Risk ratios (RR) and hazard ratios (HR) were estimated for hMPV compared to RSV hospitalizations. Results This study included 2859 hMPV-associated and 3029 RSV-associated hospitalizations. Approximately 30% of hMPV and RSV hospitalizations had an extended hospital stay (≥7 days) and about 15% were admitted to the ICU. The risk of an extended hospital stay was lower in hMPV than RSV hospitalizations (RR: 0.91 95% CI: 0.84–0.99). Over half of hMPV and RSV hospitalizations had pneumonia diagnoses; the risk was higher in hMPV hospitalizations (RR: 1.17 1.12–1.23). 1-year mortality risk was lower in hMPV compared to RSV hospitalizations (HR: 0.84 0.74-0.94). The risk of most outcomes, including the occurrence of complications, exacerbation of chronic diseases, in-hospital mortality, and readmission was comparable between hMPV and RSV hospitalizations. Conclusions Both hMPV and RSV hospitalizations were associated with substantial and similar healthcare resource utilization and morbidity, highlighting the importance of clinical appreciation of severe outcomes associated with hMPV in hospitalized adults.
Rayens et al. (Tue,) studied this question.