RSV, or respiratory syncytial virus, spreads mainly through respiratory droplets when an infected person coughs or sneezes. The virus enters your body through your eyes, nose, or mouth, either directly from droplets in the air or when you touch a contaminated surface and then touch your face. Most people who catch RSV start showing symptoms within 4 to 6 days of exposure.
How RSV Spreads From Person to Person
RSV travels in the tiny droplets that fly into the air when someone coughs, sneezes, or talks. If those droplets land on or near your eyes, nose, or mouth, the virus can infect you. This is the most direct route of transmission and the reason RSV tears through households so quickly once one person gets sick.
The virus also survives on surfaces. If someone with RSV touches a doorknob, countertop, toy, or crib rail, the virus can linger there for hours. You pick it up on your hands, rub your eye or nose without thinking, and that’s enough. This surface-to-hand-to-face chain is a major reason RSV spreads so easily among young children, who constantly touch objects and then touch their faces.
When Someone With RSV Is Contagious
People with RSV are typically contagious for 3 to 8 days. The tricky part is that they can become contagious a day or two before any symptoms appear, which means they’re spreading the virus before anyone knows they’re sick. Research on household transmission found that about 30% of secondary infections happened before the first person in the household even showed symptoms.
Infants and people with weakened immune systems are a different story. They can continue shedding the virus for 4 weeks or longer, even after their symptoms have cleared. This extended contagious window makes it harder to contain spread in settings like hospitals or homes with newborns.
Asymptomatic infections are also common. One study found that roughly 42% of RSV infections produced no symptoms at all when researchers tested people regularly regardless of how they felt. Those silent infections can still pass the virus to others, though the exact risk is harder to pin down.
Where RSV Spreads Most Easily
RSV thrives wherever people are in close contact for extended periods. Daycare centers are a classic hot spot because young children share toys, put things in their mouths, and have developing immune systems. A single infected child can set off a chain of infections across an entire room within days.
Nursing homes and long-term care facilities face similar challenges. Staff members move between rooms and units, communal dining areas bring residents together, and new admissions or transfers can introduce the virus to previously unaffected parts of the building. Older adults in these settings may not even show typical respiratory symptoms, making outbreaks harder to catch early. Visitors can also carry the virus in or be exposed to it during their visit.
Households with school-age children are another common source. Older kids often catch RSV at school and bring it home with mild cold symptoms, then pass it to a younger sibling or grandparent who is far more vulnerable to serious illness.
Who Gets the Sickest
Nearly all children catch RSV by the time they turn 2. For most older kids and healthy adults, it feels like a regular cold: runny nose, cough, mild fever. The virus becomes dangerous at the extremes of age and in people with compromised immune systems.
Infants under 6 months are at the highest risk for severe disease, especially premature babies and those with heart or lung conditions. In young infants, RSV can move into the lower airways and cause bronchiolitis (inflammation of the small airways in the lungs) or pneumonia. Warning signs include rapid or labored breathing, flaring nostrils, and a bluish tint to the lips or fingernails.
Adults over 65, particularly those with chronic heart or lung disease, are the other high-risk group. RSV hospitalizes tens of thousands of older adults each year, and the illness can worsen existing conditions like COPD or heart failure.
How to Reduce Your Risk
Basic hygiene goes a long way. Wash your hands frequently with soap and water for at least 20 seconds, avoid touching your face, and clean high-touch surfaces regularly. If you’re sick, stay away from infants and older adults as much as possible, and cover your coughs and sneezes.
For infants, there are now two prevention strategies. Pregnant women can receive the RSV vaccine (Abrysvo) during pregnancy, which passes protective antibodies to the baby before birth. Alternatively, babies younger than 8 months entering their first RSV season can receive a preventive antibody injection if their mother wasn’t vaccinated during pregnancy, if her vaccination status is unknown, or if the baby was born within 14 days of the mother’s vaccination. Real-world data show this antibody treatment is at least 70% effective at preventing RSV hospitalizations in infants, and clinical trials found it prevented roughly 80% of hospitalizations.
Children between 8 and 19 months who are at increased risk, including those with chronic lung disease, severe immune deficiency, cystic fibrosis with significant lung involvement, or American Indian and Alaska Native children, are recommended to receive protection before their second RSV season as well.
RSV season in most of the United States runs from fall through spring, with cases peaking in winter. Timing preventive measures to this window gives infants and high-risk individuals the best protection during the months when the virus circulates most heavily.