RSV season in the United States typically runs from fall through spring, with most activity concentrated between October and March. As of spring 2025, RSV activity has peaked in most regions of the country and is now declining, with the national test positivity rate dropping to around 4.3% by mid-April.
Where RSV Activity Stands Now
National surveillance data shows RSV is on a steady downward slope. The percentage of tests coming back positive for RSV fell from 8.7% in mid-March to 4.3% by the week ending April 18, a clear sign the 2024-2025 season is winding down. While some virus is still circulating, the worst of the season has passed for most of the country.
That said, “most regions” doesn’t mean all. RSV doesn’t switch off uniformly. Some areas, particularly in the South, tend to see activity linger or shift earlier than northern states. If you’re tracking local conditions, your state health department or pediatrician’s office will have the most specific picture for your area.
When RSV Season Typically Starts and Peaks
In most of the continental U.S., RSV begins circulating in the fall and peaks sometime in winter, usually between December and February. The CDC defines the seasonal administration window for infant protection as October 1 through March 31, which gives a practical outline of when the virus poses the most risk.
The timing shifts depending on where you live. Florida and the Southeast consistently see RSV epidemics begin earlier than the rest of the country, sometimes as early as late summer. Regions farther north and west tend to see later onset. This geographic pattern held true both before and after the pandemic disrupted normal respiratory virus cycles.
Post-pandemic seasons have been somewhat unpredictable. The 2021 RSV season arrived in summer, catching many families off guard. Seasons since then have trended closer to the historical fall-winter pattern, but year-to-year variation remains normal.
Who RSV Hits Hardest
RSV infects nearly all children by age two, and for most of them it looks like an ordinary cold: runny nose, cough, mild fever. The danger is concentrated in a few groups. Infants under six months old are most vulnerable to severe illness because their airways are tiny and their immune systems are still developing. Older adults, especially those with heart or lung disease, also face serious complications.
In infants, RSV can move beyond the nose and throat into the lower airways, causing bronchiolitis or pneumonia. Warning signs that set RSV apart from a typical cold include wheezing, rapid or labored breathing, visible pulling in of the chest muscles with each breath, flaring nostrils, and pauses in breathing. These symptoms warrant immediate medical attention.
New Prevention Tools Are Making a Difference
The 2024-2025 season is the first full season with widespread use of newer RSV prevention products, and the early results are striking. RSV hospitalization rates among infants under eight months dropped by an estimated 43% compared to pre-pandemic averages. The effect was even more pronounced in the youngest babies: hospitalization rates among infants under three months fell by roughly 50%.
Two tools are driving these numbers. One is a single-dose antibody given to newborns, recommended for babies under eight months entering their first RSV season if the mother did not receive an RSV vaccine during pregnancy. Infants born between October and March are ideally given this protection within a week of birth, during the hospital stay. The second is a maternal vaccine given during pregnancy, which passes protective antibodies to the baby before birth.
For older adults, an RSV vaccine is available and can be given at any time of year. It provides the most benefit when administered in late summer or early fall, before the season ramps up. August through October is the recommended window for most of the continental U.S.
Planning Ahead for Next Season
If you’re a parent expecting a baby this fall, or you’re over 50 with chronic health conditions, the time to think about RSV protection is before the season starts, not once cases are surging. For pregnant individuals, that means discussing RSV vaccination with your provider during the third trimester if your due date falls during RSV season. For older adults, scheduling a vaccine in September or October puts you in the best position heading into winter.
Everyday precautions also matter during peak months. RSV spreads through respiratory droplets and contaminated surfaces, and the virus can survive on hard surfaces for several hours. Frequent handwashing, keeping sick family members away from newborns, and cleaning shared surfaces are simple steps that reduce transmission, particularly in households with infants or older adults at risk for severe disease.