Monitoring Report: Respiratory Viruses - January 2025 Data
Authors: Gratzl Samuel , Cartwright Brianna M Goodwin , Gilbert Karen , Rodriguez Patricia J , Do Duy , Stucky Nicholas L 
Published: November 2024

Background

Few sources regularly monitor hospitalizations associated with respiratory viruses. This study provides current hospitalization trends associated with six common respiratory viruses: COVID-19, influenza, human metapneumovirus (HMPV), parainfluenza virus, respiratory syncytial virus (RSV), and rhinovirus.

Objective

This study aims to supplement the surveillance data provided by the CDC by describing latest trends (through February 02, 2025) overall and for each respiratory virus. This study also provides valuable insight into two at-risk populations: infants and children (age 0-4) and older adults (age 65 and over).

Methods

Using a subset of real-world electronic health record (EHR) data from Truveta, a growing collective of health systems that provides more than 18% of all daily clinical care in the US, we identified people who were hospitalized between October 01, 2020 and February 02, 2025. We identified people who tested positive for any of the six respiratory viruses within 14 days of the hospitalization. We report weekly trends in the rate of hospitalizations associated with each virus per all hospitalizations for the overall population and the two high-risk sub populations: infants and children and older adults.

Results

We included 697,733 hospitalizations of 643,063 unique patients who tested positive for a respiratory virus between October 01, 2020 and February 02, 2025.

Overall, the rate of hospitalizations associated with respiratory viruses slightly increased from late December 2024 into January 2025. Between the last week of December and the week ending January 27, there was a 3.1% increase in respiratory virus-associated hospitalizations; respiratory virus-associated hospitalizations accounted for 9.6% of all hospitalizations. There was a large increase in influenza-associated hospitalizations (+53.8%), which rose from 4.4% to 6.8% of all hospitalizations. In contrast, hospitalization rates associated with other respiratory viruses declined. The population 0-4 years old and over 65 saw similar increases in influenza-associated hospitalizations; the hospitalization rate at the end of January is 2-fold greater than last season’s peak (October 2023 – September 2024). The population over 65 also saw increases in rhinovirus-associated hospitalizations.

Discussion

These data highlight a shifting landscape in respiratory virus-associated hospitalizations, with influenza emerging as the primary concern. While overall hospitalizations associated with respiratory viruses saw only a slight increase, influenza-associated hospitalizations rose dramatically across all age groups, particularly in young children and older adults. Conversely, RSV and COVID-associated hospitalizations declined, marking a shift from previous trends. These findings underscore the importance of continued surveillance and public health measures to address the evolving impact of respiratory viruses, ensuring that rising influenza activity does not place additional strain on healthcare systems.