RSV is most contagious during the first few days of symptoms, and people typically stay contagious for three to eight days. Some people, especially infants and those with weakened immune systems, can spread the virus for up to four weeks. The time to worry is when breathing becomes difficult, symptoms worsen instead of improve, or a high-risk person — a young infant, an older adult, or someone with heart or lung disease — develops the infection.
What Is RSV and How Does It Spread?
Respiratory syncytial virus is a common respiratory virus. Most children have had it by age two. For most healthy adults and older children, it causes cold-like symptoms that clear up on their own.
RSV spreads mainly through respiratory droplets when an infected person coughs or sneezes. It also spreads through direct contact — touching a surface with the virus on it, then touching your eyes, nose, or mouth. The virus can survive on hard surfaces for several hours. On hands, it survives for less time, but still long enough to cause infection.
This is why RSV spreads so easily in households and daycare settings. It does not need close face-to-face contact the way some viruses do. A contaminated doorknob or toy can be enough.
When Is RSV Contagious?
People with RSV are usually contagious for three to eight days. They are most contagious during the first few days of illness, often before they realize they are sick.
That early contagious window matters. A person can spread RSV a day or two before symptoms appear. This means someone who feels fine can still pass the virus to others.
Certain groups stay contagious longer. Infants and people with weakened immune systems may shed the virus for up to four weeks, even after symptoms improve. This is one reason RSV spreads so effectively in hospitals, nursing homes, and childcare centers.
The virus is not contagious after it clears. Once the immune system controls the infection, the person is no longer spreading it to others.
How Long Does RSV Last?
RSV symptoms usually last one to two weeks in healthy adults and older children. Symptoms tend to peak around day three to five, then gradually improve.
A cough can linger longer than other symptoms. It is not unusual for a cough to last two to three weeks after the infection itself has resolved. This does not necessarily mean the person is still contagious.
In infants and older adults, RSV can last longer and cause more serious illness. Infants may have symptoms for two to three weeks. Older adults with underlying conditions may take longer to recover and may develop complications such as pneumonia.
RSV vs. Cold vs. Flu: How Can You Tell the Difference?
RSV, the common cold, and influenza all cause similar symptoms. It is often hard to tell them apart without testing. The table below shows the typical patterns, but there is overlap.
| Feature | RSV | Common Cold | Flu |
|---|---|---|---|
| Onset | Gradual | Gradual | Sudden |
| Fever | Common in children, less common in adults | Rare | Common, often high |
| Body aches | Mild | Rare | Common and significant |
| Cough | Common, can be persistent | Mild | Common |
| Wheezing | More common in infants and young children | Rare | Rare |
| Fatigue | Moderate | Mild | Often severe |
Wheezing in a young child is a clue that points more toward RSV than a cold. But testing is the only way to know for certain. Many clinics and hospitals can test for RSV along with flu and COVID-19 using a single swab.
Who Is at Highest Risk for Severe RSV?
RSV is not dangerous for most people. But certain groups face a much higher risk of severe illness, hospitalization, and complications.
- Infants under six months, especially premature infants
- Children under two with congenital heart disease or chronic lung disease
- Adults 65 and older
- Adults with chronic heart failure, chronic obstructive pulmonary disease, or asthma
- People with weakened immune systems from illness or medication
- Adults living in nursing homes or long-term care facilities
For these groups, RSV can lead to bronchiolitis (inflammation of the small airways in the lungs), pneumonia, or worsening of existing heart and lung conditions. Hospitalization may be needed for oxygen support or breathing assistance.
When Should You Worry About RSV?
Most RSV infections resolve without medical intervention. But some signs mean it is time to seek care.
In infants, watch for breathing that is fast, labored, or accompanied by grunting sounds. Flaring nostrils or the chest pulling in with each breath are warning signs. A pause in breathing — called apnea — is a serious sign and needs emergency care. Also watch for poor feeding, fewer wet diapers, or unusual sleepiness.
In children and adults, seek medical attention if breathing becomes difficult, lips or fingertips turn blue, or symptoms improve and then suddenly worsen. A high fever that does not come down, dehydration, or confusion also warrant a call to a doctor or a visit to urgent care.
Symptoms that steadily worsen over several days are more concerning than symptoms that peak and then begin to improve. RSV typically peaks around day three to five. If a person is still getting worse after that point, it is worth checking in with a healthcare provider.
How Can You Prevent the Spread of RSV?
Prevention follows the same basic steps as other respiratory viruses. Handwashing with soap and water for at least 20 seconds is one of the most effective measures. Alcohol-based hand sanitizer also works when soap and water are not available.
Avoid close contact with people who are sick. Do not share cups, utensils, or toys without washing them first. Clean frequently touched surfaces such as doorknobs, countertops, and phones.
Cover coughs and sneezes with a tissue or the inside of your elbow. Stay home when you are sick to avoid spreading the virus to others, especially those at higher risk.
Vaccines are now available for some groups. The CDC recommends RSV vaccination for adults 75 and older, and for adults 50 to 74 who are at increased risk of severe RSV. A maternal RSV vaccine is recommended during pregnancy to protect newborns. An antibody product is also available for infants to help prevent severe RSV. Because recommendations may change, check with a healthcare provider about what applies to you or your family.
Does Prior Infection Make You Immune?
No. Getting RSV once does not make you immune for life. Natural infection produces some immunity, but it is not complete and it does not last.
This is why people can get RSV repeatedly throughout their lives. Reinfections are common. In healthy adults and older children, repeat infections usually cause milder illness because the immune system remembers the virus to some degree. But in infants and older adults, reinfection can still cause serious disease.
The fact that RSV does not produce lasting immunity is one reason it circulates so widely every year, typically from late fall through early spring in most of the United States.
Frequently Asked Questions
How long is RSV contagious?
People with RSV are usually contagious for three to eight days, starting a day or two before symptoms appear. Infants and people with weakened immune systems may be contagious for up to four weeks.
Can you spread RSV without symptoms?
Yes. A person can spread RSV a day or two before any symptoms appear. This is part of why the virus spreads so easily in households and group settings.
When should I take my child to the doctor for RSV?
Seek care if your child has fast or labored breathing, chest retractions, grunting, flaring nostrils, pauses in breathing, poor feeding, or fewer wet diapers. These signs suggest the infection may be severe.
Is RSV worse than a cold?
For most healthy adults and older children, RSV is similar to a cold. For infants, older adults, and people with heart or lung disease, RSV can be much more serious and may require hospitalization.
