What Is RSV? A Plain-Language Guide to the Virus That Acts Like a Cold in Adults but Can Be Dangerous for Babies

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 17, 2026

Quick Answer

Respiratory syncytial virus (RSV) is a very common virus that infects the lungs and breathing passages, and most children are infected by age 2. [1] In adults and older children it looks like a cold. [1] Babies 12 months and younger, adults 65 and older and people with heart or lung disease can become severely ill. [1] Vaccines and antibody shots help. [1] [5]

What the research says

• A single nirsevimab shot cut medically attended RSV lung infections by about three-quarters in healthy babies. In a randomized trial of 1,490 late-preterm and term infants, medically attended RSV lower respiratory tract infection occurred in 1.2% of infants given nirsevimab versus 5.0% given placebo, an efficacy of 74.5% (95% CI 49.6 to 87.1). The difference in RSV hospitalization (0.6% versus 1.6%) was not statistically significant in this trial. (Hammitt et al., N Engl J Med, 2022) [6]

• Real-world results match the trials. A meta-analysis of 27 observational studies from five countries found that nirsevimab was linked to much lower odds of RSV-related hospitalization (odds ratio 0.17; 95% CI 0.12 to 0.23), ICU admission (0.19; 0.12 to 0.29), and RSV lower respiratory tract infection (0.25; 0.19 to 0.33) in infants 0 to 12 months old. (Sumsuzzman et al., Lancet Child Adolesc Health, 2025) [7]

• Vaccination during pregnancy protects newborns. In the MATISSE trial of 7,420 pregnant participants, the RSVpreF vaccine had an efficacy of 82.4% (95% CI 57.5 to 93.9) against severe RSV-associated medically attended lower respiratory tract illness within 90 days of birth and 70.0% (95% CI 50.6 to 82.5) within 180 days, with no new safety concerns identified. (Simões et al., Obstet Gynecol, 2025) [8]

What Is Respiratory Syncytial Virus (RSV)?

RSV stands for respiratory syncytial virus. It is a virus that causes infections of the lungs and respiratory tract — the airways you use to breathe. It is so common that most children have been infected with it by age 2. [1] The virus can also infect adults.

In adults and older, healthy children, RSV causes mild symptoms that typically mimic the common cold. Self-care measures are usually all that's needed to relieve any discomfort. [1]

However, RSV can cause severe infection in certain people, including babies 12 months and younger (infants) — especially premature infants — older adults, people with heart and lung disease, and anyone with a weak immune system (immunocompromised). [1]

How Does RSV Affect Healthy Children and Adults Differently?

For healthy older children and adults, RSV is usually a brief, manageable illness. Most children and adults recover in one to two weeks, although some might have repeated wheezing afterward. [1]

For high-risk people, the same virus is a different story. Severe or life-threatening infection requiring a hospital stay may occur in premature infants or in anyone who has chronic heart or lung problems. [1]

Group	Typical RSV Experience
Healthy adults and older children	Mild cold-like symptoms; self-care is usually enough [1]
Infants (babies 12 months and younger)	Most severely affected; can develop serious breathing problems [1]
Premature infants	Higher risk of severe or life-threatening infection [1]
Older adults	Higher risk of severe infection, especially age 65 and older [1]
People with heart, lung, or immune problems	Higher risk of complications and hospitalization [1]

RSV is usually a cold for healthy adults and older children — but fast breathing, wheezing, or bluish skin means it needs attention.

What Are the Symptoms of RSV?

Signs and symptoms of RSV infection most commonly appear about four to six days after exposure to the virus. [1] [3] What you notice depends a lot on the age and health of the person who is sick.

Mild Symptoms in Adults and Older Children

In adults and older children, RSV usually causes mild cold-like signs and symptoms. These may include a congested or runny nose, a dry cough, a low-grade fever, a sore throat, sneezing, and headache. [1]

Symptoms of a Severe RSV Infection

RSV infection can spread to the lower respiratory tract, causing pneumonia or bronchiolitis. [1] Bronchiolitis is inflammation of the small airway passages entering the lungs. Signs and symptoms of a more serious infection may include:

• Fever

• Severe cough [1]

• Wheezing — a high-pitched noise that's usually heard on breathing out (exhaling) [1]

• Rapid breathing or difficulty breathing — the person may prefer to sit up rather than lie down [1]

• Bluish color of the skin due to lack of oxygen (cyanosis) [1]

Symptoms of Severe RSV in Infants

Infants are most severely affected by RSV. Signs and symptoms of severe RSV infection in infants include short, shallow, and rapid breathing; struggling to breathe, where the chest muscles and skin pull inward with each breath; cough; poor feeding; unusual tiredness (lethargy); and irritability. [1]

Symptom	What You Might See
Runny or congested nose	Wet or stuffy nose
Dry cough	Cough without mucus
Low-grade fever	Mild fever
Sore throat	Pain or scratchiness when swallowing
Sneezing	Repeated sneezing
Headache	Head pain
Wheezing	High-pitched noise when breathing out [1]
Rapid or difficult breathing	Breathing fast; may sit up instead of lying down
Bluish skin (cyanosis)	Blue tint from lack of oxygen — a warning sign [1]

How Does RSV Compare to COVID-19?

Because RSV and COVID-19 are both types of respiratory viruses, some of their symptoms can be similar. In children, COVID-19 often results in mild symptoms such as fever, runny nose, and cough. For adults with COVID-19, symptoms may be more severe and may include trouble breathing. [1]

Having RSV may lower immunity and increase the risk of getting COVID-19 — for kids and adults. And these infections may occur together, which can worsen the severity of COVID-19 illness. [1] If you have symptoms of a respiratory illness, your doctor may recommend testing for COVID-19. [1]

When Should You See a Doctor for RSV?

Seek immediate medical attention if your child — or anyone at risk of severe RSV infection — has difficulty breathing, a high fever, or a blue color to the skin, particularly on the lips and in the nail beds. [1]

Fast or labored breathing, a chest that pulls in, poor feeding, and unusual sleepiness are the warning signs in babies.

How Does RSV Spread?

Respiratory syncytial virus enters the body through the eyes, nose, or mouth. [1] [4] It spreads easily through the air on infected respiratory droplets. You or your child can become infected if someone with RSV coughs or sneezes near you. [1] [4] The virus also passes to others through direct contact, such as shaking hands. [1]

The virus is surprisingly tough on surfaces. It can live for hours on hard objects such as countertops, crib rails, and toys. [1] [4] Touch your mouth, nose, or eyes after touching a contaminated object and you're likely to pick up the virus. [1]

When is someone most contagious? An infected person is most contagious during the first week or so after infection. [1] But in infants and those with weakened immunity, the virus may continue to spread even after symptoms go away, for up to four weeks. [1] [4]

Route of Spread	How It Happens
Airborne droplets	Someone with RSV coughs or sneezes near you
Direct contact	Shaking hands with an infected person [1]
Contaminated surfaces	Virus lives for hours on countertops, crib rails, and toys; then you touch your mouth, nose, or eyes
Entry points	The virus enters the body through the eyes, nose, or mouth

RSV travels through droplets, handshakes, and surfaces — and can live on cribs, counters, and toys for hours.

Who Is at Risk of Severe RSV?

By age 2, most children will have been infected with RSV, but they can get infected more than once. [1] Children who attend child care centers or who have siblings who attend school are at a higher risk of exposure and reinfection. [1] RSV season — when outbreaks tend to occur — is the fall to the end of spring. [1]

People at Risk of Severe or Life-Threatening RSV

Risk Factor	Who It Affects
Age	Infants, especially premature infants or babies 6 months or younger; older adults, especially 65 and older [1]
Congenital heart disease	Children with heart disease present from birth [1]
Chronic lung disease	Children with long-term lung conditions [1]
Weakened immune system	Children or adults with diseases such as cancer, or treatments such as chemotherapy [1]
Neuromuscular disorders	Children with conditions such as muscular dystrophy [1]
Adult heart or lung disease	Adults with heart or lung conditions [1]
Setting	Children in child care centers or with school-age siblings (more exposure) [1]

What Problems Can RSV Cause?

RSV complications can be significant, especially for high-risk groups, and include hospitalization, pneumonia and middle ear infections. [1] The most common complications include:

Hospitalization. A severe RSV infection may require a hospital stay so that doctors can monitor and treat breathing problems and give intravenous (IV) fluids. [1]

Pneumonia. RSV is the most common cause of inflammation of the lungs (pneumonia) or the lungs' airways (bronchiolitis) in infants. [1] These complications occur when the virus spreads to the lower respiratory tract. [1] Lung inflammation can be quite serious in infants, young children, older adults, immunocompromised individuals, or people with chronic heart or lung disease. [1]

Middle ear infection. If germs enter the space behind the eardrum, you can get a middle ear infection (otitis media). [1] This happens most frequently in babies and young children. [1]

Asthma. There may be a link between severe RSV in children and the chance of developing asthma later in life. [1]

Repeated infections. Once you've had RSV, you could get infected again. It's even possible for it to happen during the same RSV season. [1] However, symptoms usually aren't as severe — typically it's in the form of a common cold. [1] But they can be serious in older adults or in people with chronic heart or lung disease. [1]

Complication	What Happens
Hospitalization	Severe infection needs monitoring, breathing treatment, and IV fluids [1]
Pneumonia or bronchiolitis	Virus spreads to the lower respiratory tract, inflaming the lungs or small airways [1]
Middle ear infection	Germs enter the space behind the eardrum; common in babies and young children [1]
Asthma	Severe RSV in childhood may be linked to developing asthma later [1]
Repeated infections	You can get RSV again, even in the same season [1]

How Is RSV Diagnosed?

Your doctor may suspect RSV based on the findings of a physical exam and the time of year the symptoms occur. [2] During the exam, the doctor will listen to the lungs with a stethoscope to check for wheezing or other abnormal sounds. [2]

Laboratory and imaging tests aren't usually needed. However, they can help diagnose RSV complications or rule out other conditions that may cause similar symptoms. [2] Tests may include:

Test	What It Checks
Physical exam	Doctor listens to the lungs with a stethoscope for wheezing or abnormal sounds [2]
Blood tests	White cell counts; look for viruses, bacteria, and other germs [2]
Chest X-ray	Checks for lung inflammation [2]
Swab	Secretions from inside the mouth or nose to check for signs of the virus [2]
Pulse oximetry	Painless skin monitor that detects lower than normal levels of oxygen in the blood [2]

How Is RSV Treated?

Treatment for RSV generally involves self-care measures to make your child more comfortable — known as supportive care. [2] But hospital care may be needed if severe symptoms occur. [2]

Supportive Care at Home

Your doctor may recommend an over-the-counter medication such as acetaminophen (Tylenol, others) to reduce fever. Never give aspirin to a child. [2] [3] Use of nasal saline drops and suctioning may help clear a stuffy nose. [2] Your doctor may prescribe antibiotics if there's a bacterial complication, such as bacterial pneumonia. [2]

Keep your child as comfortable as possible. Offer plenty of fluids and watch for signs of loss of body fluids (dehydration), such as dry mouth, little to no urine output, sunken eyes, and extreme fussiness or sleepiness. [2]

Hospital Care

If the RSV infection is severe, a hospital stay may be necessary. Treatments at the hospital may include intravenous (IV) fluids, humidified oxygen, and a breathing machine (mechanical ventilation), in rare cases. [2]

Notably, an inhaler (bronchodilator) or steroids are not proved to be helpful in treating RSV infection. [2]

Treatment Level	What It Involves
Supportive care	Acetaminophen for fever; saline drops and suctioning; fluids; comfort [2]
Antibiotics	Only if a bacterial complication such as bacterial pneumonia is present [2]
Hospital care	IV fluids; humidified oxygen; breathing machine in rare cases [2]

What Can You Do at Home to Relieve RSV Symptoms?

An RSV infection may not be shortened, but its symptoms can be eased with comfort, moist air, plenty of fluids and other home care. If your child has RSV, do your best to comfort or distract him or her — cuddle, read a book, or play a quiet game. [2] Other tips for relieving symptoms are:

Create moist air to breathe. Keep the room warm but not overheated. If the air is dry, a cool-mist humidifier or vaporizer can moisten the air and help ease congestion and coughing. Be sure to keep the humidifier clean to prevent the growth of bacteria and molds. [2]

Drink fluids. Continue breastfeeding or bottle-feeding your infant as you would normally. For older children and adults, keep a steady supply of cool water at the bedside. Offer warm fluids, such as soup, which may help loosen thickened secretions. Ice pops may be soothing as well. [2]

Try saline nasal drops. Over-the-counter drops are a safe, effective way to ease congestion, even for young children. [2] Follow your doctor's recommendations and the instructions on the product.

Use over-the-counter pain relievers. OTC pain relievers such as acetaminophen may help reduce fever and relieve a sore throat. Ask a doctor for the correct dose for your child's age. [2]

Stay away from cigarette smoke. Secondhand smoke can aggravate symptoms. [2]

Self-Care Step	How It Helps
Comfort and distraction	Cuddling, reading, or quiet games ease distress [2]
Moist air	Cool-mist humidifier eases congestion and coughing [2]
Fluids	Breast milk, formula, cool water, soup, or ice pops prevent dehydration [2]
Saline nasal drops	Safe and effective way to ease congestion, even for young children
Pain relievers	Acetaminophen reduces fever and sore throat [2]
No smoke	Avoiding secondhand smoke prevents worsening symptoms [2]

Can RSV Be Prevented?

RSV can infect anyone, but premature babies and young infants, as well as older adults with heart or lung disease or a weakened immune system, are at higher risk of severe infection. [1] There are now medical options to protect the most vulnerable.

Protection for Babies and High-Risk Young Children

Two main FDA-approved options exist to help prevent young infants from getting severe RSV. One is an antibody product given to the infant. The other is an RSV vaccine for pregnant people to help protect their baby from birth through 6 months of age. [1] [5]

Antibody product called nirsevimab (Beyfortus). This antibody product is a single-dose shot given in the month before or during RSV season. [1] [5] It's for babies younger than 8 months born during or entering their first RSV season. [1] [5] Nirsevimab also can be given to children 8 months through 19 months old who are at higher risk of severe RSV disease through their second RSV season. [1] [5] In the U.S., the RSV season typically is November through March, but it varies in Florida, Alaska, Hawaii, Puerto Rico, Guam, and other U.S. Pacific island territories. [1]

In rare situations, when nirsevimab is not available or a child is not eligible for it, another antibody product called palivizumab may be given. [1] But palivizumab requires monthly shots given during the RSV season, while nirsevimab is only one shot. [1] Palivizumab is not recommended for healthy children or adults. [1]

Vaccine for pregnant people. The FDA approved an RSV vaccine called Abrysvo for pregnant people to prevent RSV in infants from birth through 6 months of age. [1] [5] A single-dose shot of Abrysvo can be given sometime from 32 weeks through 36 weeks of pregnancy during September through January in the U.S. [1] [5]

Vaccine for Older Adults

Older adults have weaker immune systems, especially those with ongoing conditions such as heart or lung disease. To help prevent RSV infection, the FDA approved RSV vaccines for adults age 60 and older. [1]

The CDC recommends that adults age 60 and older talk with their healthcare professional about getting an RSV vaccine, especially if they're at higher risk of getting severe RSV. [1] Two vaccines are available for this age group: Abrysvo and Arexvy. [1] The CDC does not recommend one over the other. [1] Each is a single-dose shot. [1]

Talk with your healthcare team about the benefits and risks of RSV vaccines for your situation.

Everyday Habits That Prevent RSV

Prevention Step	Why It Helps
Wash hands often	Teaching children hand-washing limits spread [1]
Avoid exposure	Cover mouth and nose when coughing or sneezing; limit baby's contact with people who have fevers or colds [1]
Keep things clean	Clean countertops, doorknobs, and handles; put used tissues in the trash right away [1]
Don't share drinking glasses	Use your own cup when you or someone else is sick; label each person's cup [1]
Don't smoke	Babies exposed to tobacco smoke have a higher RSV risk and potentially more severe symptoms; never smoke inside the house or car [1]
Wash toys regularly	Especially when your child or a playmate is sick [1]

Antibody shots, a pregnancy vaccine, and vaccines for older adults now add medical protection to everyday habits.

What is the bottom line on RSV?

RSV is the virus that practically every child meets by age 2. For healthy kids and adults, it's usually nothing more than a cold that passes in one to two weeks. But for babies, older adults, and people with heart, lung, or immune problems, it can be genuinely dangerous — and the warning signs (fast breathing, chest pulling in, poor feeding, bluish skin) deserve immediate medical attention.

The good news: treatment is mostly about making the sick person comfortable with fluids, fever medicine, and moist air, and new vaccines and antibody shots now protect both newborns and older adults. Washing hands, keeping surfaces clean, and keeping babies away from smoke close the everyday-prevention gap.

Take the Next Step

If your baby is breathing fast, struggling to breathe, feeding poorly, or running a high fever — or if anyone at high risk develops bluish skin — seek immediate medical care. For milder symptoms, talk with your healthcare professional about supportive care, and ask about RSV vaccines if you or a loved one is 60 or older, or about antibody protection if you have a baby entering RSV season.

Frequently Asked Questions

What is RSV and how common is it?

Respiratory syncytial virus (RSV) is a virus that causes infections of the lungs and respiratory tract. It is so common that most children have been infected by age 2. It can also infect adults.

Is RSV worse in babies than in adults?

Yes. Babies 12 months and younger — especially premature infants — are the most severely affected by RSV. In adults and older, healthy children, RSV symptoms are usually mild and mimic the common cold.

How long does RSV last?

Most children and adults recover in one to two weeks, although some might have repeated wheezing. Symptoms typically appear four to six days after exposure to the virus.

How does RSV spread?

RSV enters the body through the eyes, nose, or mouth and spreads through airborne droplets when an infected person coughs or sneezes, through direct contact like handshakes, and through contaminated surfaces such as countertops and toys, where the virus can live for hours.

Can you get RSV more than once?

Yes. Once you've had RSV, you can get infected again — even in the same RSV season. Repeat infections usually look like a common cold, though they can be serious in older adults or people with chronic heart or lung disease.

When should I take my baby to the doctor for RSV?

Seek immediate medical attention if your child has difficulty breathing, a high fever, or a blue color to the skin, particularly on the lips and in the nail beds.

What can I do at home for RSV symptoms?

Offer plenty of fluids, use acetaminophen (never aspirin) for fever, try saline nasal drops with suctioning, run a cool-mist humidifier, and keep your child away from cigarette smoke. These measures can't shorten the infection but can relieve symptoms.

Are there vaccines for RSV?

Yes. FDA-approved RSV vaccines are available for adults 60 and older (Abrysvo and Arexvy) and for pregnant people to protect babies from birth through 6 months (Abrysvo). Babies can also receive a protective antibody shot called nirsevimab before or during RSV season.

Related Reading

• Pneumonia: Complete Guide to Symptoms, Causes, and Treatment

• Bronchiolitis: Symptoms, Causes, and Treatment

• Premature Birth: Complete Guide to Signs, Causes, and Care

PCR Test: How It Works, What It Detects and What Results Mean (Including COVID-19) explains how PCR testing detects infections and gene changes.

Nasopharyngeal Swab: Testing for COVID-19, Flu, RSV and More explains the deep nose swab used to test for respiratory infections.

References

1. Mayo Clinic Staff. Respiratory syncytial virus (RSV): Symptoms and causes. Mayo Clinic. Accessed October 14, 2026. https://www.mayoclinic.org/diseases-conditions/respiratory-syncytial-virus/symptoms-causes/syc-20353098

2. Mayo Clinic Staff. Respiratory syncytial virus (RSV): Diagnosis and treatment. Mayo Clinic. Accessed October 14, 2026. https://www.mayoclinic.org/diseases-conditions/respiratory-syncytial-virus/diagnosis-treatment/drc-20353104

3. Centers for Disease Control and Prevention. Symptoms and care of RSV. CDC. Accessed October 14, 2026. https://www.cdc.gov/rsv/symptoms/index.html

4. Centers for Disease Control and Prevention. How RSV spreads. CDC. Accessed October 14, 2026. https://www.cdc.gov/rsv/causes/index.html

5. Centers for Disease Control and Prevention. Immunizations to Protect Infants. CDC. Last updated August 18, 2025. Accessed October 14, 2026. https://www.cdc.gov/rsv/vaccines/protect-infants.html

6. Hammitt LL, Dagan R, Yuan Y, et al. Nirsevimab for prevention of RSV in healthy late-preterm and term infants. N Engl J Med. 2022;386(9):837-846. PMID: 35235726. https://doi.org/10.1056/NEJMoa2110275

7. Sumsuzzman DM, Wang Z, Langley JM, et al. Real-world effectiveness of nirsevimab against respiratory syncytial virus disease in infants: a systematic review and meta-analysis. Lancet Child Adolesc Health. 2025;9(6):393-403. PMID: 40319903. https://doi.org/10.1016/S2352-4642(25)00093-8

8. Simões EAF, Pahud BA, Madhi SA, et al. Efficacy, safety, and immunogenicity of the MATISSE (Maternal Immunization Study for Safety and Efficacy) maternal respiratory syncytial virus prefusion F protein vaccine trial. Obstet Gynecol. 2025;145(2):157-167. PMID: 39746212. https://doi.org/10.1097/AOG.0000000000005816

Disclaimer: This guide is for general information only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a physician or other qualified health provider with any questions about a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read here.