Respiratory syncytial virus (RSV) is highly contagious. It spreads through respiratory droplets when an infected person coughs or sneezes, through direct contact like kissing, and by touching contaminated surfaces and then touching your face. Most people develop symptoms within 4 to 6 days of exposure, and the virus moves easily through households, daycare centers, and nursing homes.
How RSV Spreads
RSV travels primarily through respiratory droplets that land on nearby people or surfaces. You can catch it by being close to someone who coughs or sneezes, by touching a surface where the virus has landed and then touching your eyes, nose, or mouth, or through direct physical contact with an infected person.
The virus is surprisingly durable outside the body. RSV can survive for many hours on hard surfaces like tables, countertops, and crib rails. It lives for shorter periods on soft surfaces like tissues and hands, but even that window is long enough to pass the virus along through a handshake or shared toy. This is one reason RSV tears through daycare settings so efficiently: young children touch everything, share objects constantly, and then rub their faces.
How Long You’re Contagious
Most people with RSV are contagious for 3 to 8 days, starting a day or two before symptoms appear. That pre-symptomatic window is part of what makes RSV so difficult to contain. You can spread it before you even know you’re sick.
Infants and people with weakened immune systems can shed the virus for much longer, sometimes up to four weeks. This extended shedding is a major factor in household spread. Research from the University of Minnesota’s Center for Infectious Disease Research and Policy found that in households where one person was diagnosed with RSV, about 10% of other household members caught it within two weeks. The most common transmission pattern was from infants and young children to the adults around them, not the other way around. Having a child age 12 or younger in the home was a significant risk factor for the virus spreading to other family members.
Reinfection Is Common
Unlike some viruses that grant lasting immunity after infection, RSV can reinfect you repeatedly throughout your life. A study published in The Journal of Infectious Diseases tracked adults who had recovered from natural RSV infection and then re-exposed them to the same strain at intervals over two years. By two months after their initial infection, about half became reinfected. By eight months, two-thirds were reinfected. Within 26 months, 73% had caught RSV at least twice, and nearly half had three or more infections.
Even people with the highest levels of protective antibodies still had a 25% chance of reinfection when exposed. The body does build some immune response, and having two infections close together seems to extend the duration of protection. But that protection is partial and temporary. This is why RSV circulates year after year and why adults catch it multiple times, often mistaking it for a bad cold.
Who Faces the Greatest Risk
RSV infects people of all ages, but it hits hardest at the extremes. Infants under 12 months, especially premature babies, are most vulnerable to severe illness because their airways are small and their immune systems are still developing. RSV is one of the leading causes of hospitalization in babies under 6 months old.
Older adults face serious risk as well, particularly those 75 and older or those between 50 and 74 with certain chronic conditions. Heart disease, chronic lung conditions like COPD or asthma, kidney disease requiring dialysis, liver cirrhosis, sickle cell disease, severe obesity (BMI of 40 or higher), and weakened immune systems all raise the likelihood of a severe RSV infection. People living in nursing homes are also at elevated risk because of close quarters and shared spaces.
RSV Season and Timing
In most of the continental United States, RSV season runs from fall through early spring, with cases typically peaking in December and January. The virus follows a predictable annual pattern, though the exact timing can shift by a few weeks from year to year. Symptoms usually appear 4 to 6 days after exposure, so if someone in your household gets sick, you’ll know within about a week whether you’ve caught it too.
Vaccines and Prevention
Three RSV vaccines are now available for adults: Arexvy (GSK), mResvia (Moderna), and Abrysvo (Pfizer). The CDC recommends a single dose for all adults 75 and older, and for adults 50 to 74 who have conditions that increase their risk of severe illness. This is not an annual vaccine. One dose is the current recommendation, and it can be given alongside other vaccines like flu or COVID shots at the same visit.
For the best protection, vaccination in late summer or early fall (August through October) lines up with the start of RSV season. Eligible adults who haven’t been vaccinated can receive it at any time of year, though the benefit is greatest when timed before seasonal circulation picks up.
For infants, a monoclonal antibody treatment is available that provides passive protection during their first RSV season. Pregnant individuals can also receive RSV vaccination during weeks 32 through 36 of pregnancy, which passes protective antibodies to the baby before birth.
Practical Steps to Reduce Spread
Because RSV spreads through both droplets and surfaces, prevention comes down to the same basics that limit any respiratory virus. Washing your hands frequently with soap and water for at least 20 seconds is the single most effective measure. Cleaning high-touch surfaces like doorknobs, light switches, and toys helps reduce the hours-long window the virus has on hard surfaces. Avoiding close contact with people who have cold-like symptoms, and staying home when you’re symptomatic yourself, limits the chain of transmission.
For parents of newborns, keeping sick visitors away during RSV season and asking anyone who handles the baby to wash their hands first makes a meaningful difference. Since most household transmission flows from young children to adults and other family members, teaching older siblings to wash hands and cover coughs is especially important when a new baby is in the home.