Respiratory syncytial virus (RSV) is a common respiratory infection that causes cold-like symptoms in most people but can lead to serious illness, including pneumonia and bronchiolitis, in infants, young children, and older adults.1 RSV typically follows a seasonal pattern, rising in the fall and peaking in the winter months.2,3 The COVID-19 pandemic disrupted these patterns significantly: RSV activity was extremely low during the 2020–2021 season, returned off-season in summer 2021, and then surged to historically high levels during the 2022–2023 winter.4,5 In 2023, the FDA approved the first RSV vaccines for older adults and for use during pregnancy to protect infants, opening a new era of RSV prevention.6,7,8,9 While much attention has focused on the changing volume of RSV cases, less is known about how the severity distribution of RSV encounters across care settings has evolved. Understanding whether the share of RSV cases requiring ICU admission or hospitalization has changed over time, and how these patterns differ by age, can help healthcare systems plan resource allocation and inform ongoing prevention strategies.
We studied 2 million U.S. patients who sought medical care for RSV between January 2017 and January 2026. For each patient encounter, we classified the highest level of care into four mutually exclusive categories: ICU admission, hospital admission, emergency department (ED) visit, or office visit. This acuity distribution was computed for the overall population and stratified by age group: under 2, 2–4, 5–17, 18–49, 50–64, 65–74, and 75 years and older.
The distribution of RSV encounters across care settings has shifted markedly over the past nine years. In January 2017, 8.2% of RSV encounters resulted in ICU admission, 21.9% in hospital admission, 29.4% in ED visits, and 40.6% in office visits, as seen in Figure 1. By January 2026, those proportions had shifted to 3.8% ICU, 11.8% admission, 45.0% ED, and 39.4% office visits. Notably, the office visit share remained relatively steady throughout the study period (40.6% in January 2017 and 39.4% in January 2026) indicating that the shift toward ED care came primarily from hospitalizations and ICU admissions, not from patients who would otherwise have been seen in outpatient settings. This lower-acuity pattern began during the COVID-19 pandemic and has persisted through subsequent seasons.
We additionally looked at this distribution by age group. Among adults aged 75 and older, hospitalizations and ICU admissions accounted for 79.0% of RSV encounters in January 2017 but fell to 47.2% by January 2026. The ED share in this group more than tripled over that period, growing from 6.9% to 24.6%. Adults aged 65–74 followed a similar trajectory. For children under 2 years old, ICU admissions declined from 7.4% of cases in January 2017 to 3.8% in January 2026, and ED visits grew from 31.2% to 47.6%. Children aged 2–4 had a similar pattern. School-aged children (ages 5–17) saw the largest proportional decline in inpatient care: their combined hospitalization and ICU share fell from 37.3% in January 2017 to 6.0% in January 2026.
