Respiratory syncytial virus (RSV) is a common respiratory virus that usually causes cold-like illness—but in the very young and the very old, it can turn dangerous quickly. RSV is the leading cause of infant hospitalization in the United States, and it also drives substantial illness and deaths among older adults. New prevention tools are changing that picture, but only if people can access them.
What is RSV?
RSV infects the lining of the nose, throat, and lungs. In infants and young children, it’s a major cause of bronchiolitis and pneumonia; in older adults and those with underlying conditions, it can trigger severe lower-respiratory disease. Typical symptoms start mild—runny nose, less feeding, cough—and can worsen over a few days. In babies under six months, watch for irritability, pauses in breathing (apnea), or trouble feeding. Most children encounter RSV by age two.
A brief history
RSV was first identified in 1956 during an outbreak of colds among chimpanzees at Walter Reed; researchers called it the “chimpanzee coryza agent.” Soon after, scientists isolated the same agent from sick children and renamed it respiratory syncytial virus for the “syncytia” (fused cells) it causes in the lab. Since then, RSV has been recognized as the dominant cause of lower-respiratory illness in young children worldwide.
The U.S. burden today
In a typical year, 58,000–80,000 U.S. children under five are hospitalized for RSV; 100–300 die. Among older adults, RSV leads to tens of thousands of hospitalizations and thousands of deaths annually, with the highest risk in those 75+ or living in long-term care and in people with COPD or heart failure.
Seasonally, RSV activity rises in the fall, peaks in winter, and tapers in spring, though timing can vary by region. Starting in 2023–2024, the U.S. entered a new era of prevention: a long-acting antibody (nirsevimab) for infants and a maternal RSV vaccine (Abrysvo) given late in pregnancy so protective antibodies pass to the newborn. Early national surveillance from the 2024–2025 season shows marked drops in infant RSV hospitalizations where these products were used widely.
Prevention at a glance
For most families, protection follows one of two paths: maternal vaccination during 32–36 weeks of pregnancy (seasonally, September–January in most of the U.S.), or a single nirsevimab dose for babies under 8 months entering their first RSV season (ideally before or at birth during October–March). Most infants do not need both. Clinicians consider local seasonality and family preference when choosing.
Why equity matters: who bears the brunt?
RSV doesn’t hit all communities equally. American Indian and Alaska Native (AI/AN) children have experienced some of the highest RSV hospitalization rates in the nation, with population-based studies reporting rates 1.7 to 7 times higher than U.S. averages in certain tribal regions—differences linked to overcrowding, lack of running water, and other structural conditions. CDC notes AI/AN children are 4–10 times more likely to get severe RSV than other communities.
Disparities are not limited to AI/AN families. Analyses of U.S. data show higher RSV infection and hospitalization burdens in Black and Hispanic children compared with White children, patterns that widened during the atypical 2022 season. Social vulnerability—poverty, crowded housing, transportation barriers, and language access—correlates with higher RSV hospitalization and ICU admission risk. In short, the virus exploits social fault lines.
Among older adults, RSV hospitalizations cluster in those with chronic lung or heart disease and in long-term care residents—again intersecting with inequities in underlying illness and access to preventive care. In recent surveillance, nearly 1 in 5 hospitalized adults ≥60 had a severe outcome (ICU, ventilation, or in-hospital death), underscoring why uptake of newly available adult RSV vaccines matters.
The path forward
The science is clear: preventing severe RSV in the first months of life is now highly achievable using maternal vaccination or nirsevimab—and early national data suggest real-world hospitalizations are already falling in protected infants. The challenge is delivery: making sure every baby, regardless of ZIP code or insurance, leaves the hospital protected, and that older adults at highest risk are offered vaccination in time for the season. That means aligning payer policies, embedding RSV protection in birth-hospital and discharge workflows, and bringing prevention to where families already are—prenatal care, WIC, tribal clinics, community health centers, and pharmacies.
Equity is the difference between a scientific breakthrough and a population impact. To close the gap, systems should track RSV protection by race/ethnicity and social vulnerability, invest in trusted messengers (including community health workers), and streamline bedside access so families don’t have to navigate complex benefits before their newborn’s first ride home. The payoff is tangible: fewer tiny patients struggling to breathe, fewer anxious nights in the ER, and fewer older adults facing ICU care for a virus we can blunt.
