Monitoring Report: Respiratory Viruses – December 2025 Data

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 January 04, 2026) 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 January 04, 2026. 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 1,010,216 hospitalizations of 885,367 unique patients who tested positive for a respiratory virus between October 01, 2020 and January 04, 2026.

Overall, respiratory virus associated hospitalizations increased substantially throughout December 2025. By the last week of the month, respiratory virus-associated hospitalizations accounted for 6.9% of all hospitalizations, up from 3.0% at the beginning of December (+125.3%). This increase was driven primarily by influenza, with influenza-associated hospitalizations rising sharply (+277.1%). COVID and RSV-associated hospitalizations also increased (+61.8% and +83.7%, respectively), while rhinovirus-associated hospitalizations declined slightly.

Among children aged 0–4 years, respiratory virus-associated hospitalizations remained largely stable across December and accounted for 3.6% of all hospitalizations by the end of the month (−7.2%). This stability reflected increasing influenza-associated hospitalizations (+44.6%) offset by declines in rhinovirus-, COVID-, and parainfluenza-associated hospitalizations. RSV-associated hospitalizations remained stable and continued to represent the largest share of respiratory virus associated hospitalizations in this age group (1.7%). Among adults aged 65 years and older, respiratory virus-associated hospitalizations increased substantially across December, reaching 9.4% of all hospitalizations by the last week of the month (+154.1%). Influenza-associated hospitalizations increased more than fourfold (+316.1%) and were the primary driver of this increase. COVID-, RSV-, and HMPV-associated hospitalizations also rose.

Discussion:

Respiratory virus–associated hospitalizations increased substantially overall during December 2025, accounting for nearly 7% of all hospitalizations. In the pediatric population, hospitalization rates remained relatively stable, as increases in influenza-associated hospitalizations were offset by declines in rhinovirus-, COVID-, and parainfluenza-associated hospitalizations, while RSV remained the leading cause of respiratory virus-associated hospitalizations in this age group. Among older adults, respiratory virus-associated hospitalizations rose sharply, driven primarily by a marked increase in influenza-associated hospitalizations, with additional increases observed for COVID-, RSV-, and HMPV-. Together, these patterns highlight influenza as the dominant contributor to rising respiratory hospitalization burden in December and underscore the importance of continued surveillance as seasonal respiratory virus activity intensifies, particularly among older adults at higher risk for severe outcomes.

Trends in surveillance