Respiratory Syncytial Virus (RSV)

Last Updated 11/02/2020

Author:Anastassios C. Koumbourlis, MD, MPH

About Respiratory Syncytial Virus (RSV)

Key facts about Respiratory Syncytial Virus
  • Respiratory syncytial virus (RSV) typically affects children 2 years old or younger.
  • RSV-related infections in children under 5 years of age account for more than 2 million visits to the doctor or the emergency department every year.
  • RSV is the top cause of babies under 1 year of age being kept in the hospital.

RSV is a common respiratory virus. This means it affects your lungs and breathing passages. People of all ages can catch RSV. In older children and adults, it mostly causes upper respiratory symptoms (“colds”). It can cause serious lung infections (like bronchiolitis and pneumonia) in very young babies and in children or adults with other serious health problems. These problems include heart disease the patient was born with or diseases of the muscles and nerves.

RSV can only be passed between humans. How serious the symptoms are depends on which type of virus (or strain) the patient catches. There are A and B strains of RSV. The virus is passed between people by droplets from the mouth or nose that contain the virus. RSV can live for at least a half hour on the hands and for several hours on various surfaces. RSV causes epidemics every year, usually during the winter and early spring. When these epidemics start and how long they last varies by regions.

How RSV affects your body

RSV can affect any part of the respiratory tract:

  • Nose
  • Throat
  • Windpipe, or larynx
  • The breathing tubes, or bronchi
  • The lung

The irritation (also called inflammation) can be intense.

RSV infection is most serious when it affects the small breathing tubes (called bronchioles) in the lungs. This condition is called acute bronchiolitis. RSV can also cause pneumonia, which is an infection in the rest of the lung. Because it’s often hard to tell the two illnesses RSV causes apart, health care providers often use the term lower respiratory tract infection. RSV is the most common cause of this condition in babies.

RSV bronchiolitis causes intense inflammation inside the bronchi and bronchioles. It irritates their inner lining (or epithelium) and makes it swell. This destroys the cells that make it up, including those that clear mucus from the lungs. When mucus and destroyed cells clog the breathing tubes, patients can’t breathe as easily. The clogs fill the air sacs (called alveoli) at the ends of the breathing tubes (or alveoli). Alveoli move oxygen from the lungs into the blood. If they are blocked, less oxygen reaches the patient’s body.

The inflammation also causes the muscles around the breathing tubes to tighten (bronchospasm). This closes the airways and makes breathing even harder. Because babies with RSV breathe much faster and much harder than usual, they lose a lot of fluid through the lungs and can easily become dehydrated.

How serious is RSV?
  • Most people (including babies) usually develop only mild cold-like symptoms, with a stuffed-up or runny nose and some cough.
  • About 25% to 40% of sick babies and children will have bronchiolitis or pneumonia, and about 5% to 20% of them will need a hospital stay, including intensive care.
  • Most kids who go to the hospital for RSV (especially those in intensive care) are 6 months old or less.
  • Because people don’t become fully immune to RSV after catching it, they can catch it over and over again.
  • Older adults and those with ongoing heart of lung disease or weakened immune systems are at high risk for developing severe symptoms if they catch RSV again.

Symptoms of RSV

RSV has many different symptoms. These range from mild to life threatening. Which symptoms and how serious they are depend on many factors, including the strain of the virus and whether the patient has other medical problems.

The symptoms of RSV are as follows:

  • Stuffed-up or runny nose, mild cough, and low-grade fever usually appear first for both mild and more severe cases.
  • Barking cough, which can mean major swelling of and around the vocal cords.
  • Fever, either low (less than 101°F [38.3°C])* or high (above 103°F [39.5°C])**
  • Trouble breathing in one or more of these forms:
    • Tachypnea (fast breathing). How many breaths children take per minute varies with their age. However, when babies (even the very young ones) breathe more than 60 times per minute, it is not normal. For patients who already breathe more often even when they are well (such as babies with lung disease from being born premature), tachypnea is defined as 10 to 20 more breaths per minute than normal.
    • Chest wall retractions. The child’s chest “caves in” between and under the ribs.
    • Nasal flaring. The child’s nostrils “spread out” with every breath.
  • Wheezing (a high-pitched whistling sound as the child breathes out).
  • Trouble drinking.
  • Feeling tired (called lethargy) or short-tempered (called irritable).
  • Bluish color around the mouth, lips, and fingernails (called cyanosis).
  • Stopping breathing (or apnea) is a common symptom of RSV bronchiolitis among young babies, especially those born prematurely.

*Very sick babies may actually have low temperature (less than 99.5°F [37.5°C]) despite warm clothes and blankets.

**In small, prematurely born babies, even a rectal temperature above 100°F (37.8°C) is probably abnormal.

What causes RSV?

RSV is caused by a virus that spreads when an infected person coughs or sneezes. The virus enters the body through the nose or mouth. Often, it enters through the eyes. This can happen when people rub their eyes after touching a surface coated with RSV from a cough or sneeze.

What are risk factors for RSV?

These situations make it more likely a person will catch RSV:

  • Crowded places with people who may be infected
  • Exposure to other children (such as in daycare) or to older brothers or sisters being schooled at home

These people are at higher risk for severe forms of RSV:

  • Babies younger than 6 months of age (and especially younger than 3 months of age)
  • Babies born prematurely
  • Babies born with heart disease (called congenital heart disease)
  • Babies with neuromuscular disorders (such as spinal muscular atrophy)
  • Babies, children, or adults with weakened immune systems because of a condition such as primary immunodeficiency or treatments they’re getting (such as patients having chemotherapy)
  • People with immunodeficiency, including those with certain transplanted organs, leukemia, or HIV/AIDS
  • Adults with asthma, congestive heart failure, or chronic obstructive pulmonary disease (COPD)
  • Patients with Down syndrome

Diagnosing RSV

RSV infection is often discovered by using a test. Still, in many cases, RSV is only confirmed when a health care provider examines the patient.

Besides the symptoms RSV causes, it can make other conditions the patient has worse. These conditions include asthma and COPD.

When should you see your health care provider?

Call your provider if you or your child:

  • Is having trouble breathing;
  • Has a poor appetite or is less active;
  • Has cold symptoms that become severe; or
  • Has a shallow cough that continues through the day and night.

How RSV is diagnosed

Mild RSV infections usually cause problems just in the upper respiratory tract (the nose and throat). Mild cases have the same symptoms as the common cold and don’t need a lab test.

When RSV causes a lower respiratory tract infection (such as acute bronchiolitis or pneumonia), a health care provider will usually diagnose it. Providers will examine patients and ask them or their caregiver questions about the illness. These RSV cases start as an upper respiratory illness that gets worse over a few days. Patients have more and more trouble breathing. They start wheezing and can hear crackles in both lungs.

Health care providers may suspect bronchiolitis because of RSV if there have been many cases in the community. Although RSV can occur at any time, it is much more likely during colder months. However, the exact timing of the RSV season varies across the country. You can find out when RSV season has begun from the Centers for Disease Control and Prevention (CDC) or your local health department.

If patients with RSV need to stay in the hospital, they will be given a test to confirm the virus. This is useful because such patients can be safely isolated, which will keep RSV from spreading to other patients.

Several highly accurate RSV tests can give reliable results within a few hours. Health care providers will take a small sample of the patient’s nasal mucus. Patients who develop severe disease will need more tests to make sure they don’t develop other illnesses. These tests include:

  • Chest X-ray to make sure that there are no signs of pneumonia. If there are, the patient will be given antibiotics.
  • Blood tests to check for a bacterial infection and to make sure that the infant is getting enough liquids (this is very important)
  • Blood and urine cultures for seriously ill babies (infants with RSV bronchiolitis may also have urinary tract infections)
  • Pulse oximetry, where a bandage-like sensor with a red light is wrapped around the finger or toe of a sick baby or child. The device makes sure there is enough oxygen in the patient’s blood

Treating RSV

RSV bronchiolitis has no set treatment plan, especially if the patient is treated at home. The basic treatment for infants is to keep them comfortable and lower their fever with acetaminophen. Caregivers can clear mucus from a baby’s nose with a bulb syringe. This will help them breathe easier for a while. It’s best to do this just before the baby eats so they can drink more easily.

Depending on how severe the illness is, caregivers can try many treatments. They won’t cure the RSV infection itself, but they can help patients feel better by easing symptoms and making sure the another illness doesn’t develop.

Caregivers can use one or more of these treatments :

  • Hydration. Infants, especially young ones, can get low on body fluids very easily. At home, mothers can continue breast or bottle feeding. Caregivers may need to give these in several small amounts. If patients can’t drink, they will need to be admitted to the hospital. There, they will get fluids through a tube either in their vein or down their throat.
  • Oxygen. Low oxygen (or hypoxemia) often happens in RSV bronchiolitis. Infants may receive oxygen through short tubes that feed into their nostrils. This will help them work less hard to breathe and will keep their breathing muscles from getting too tired.
  • Bronchodilators. These medications open up a patient’s breathing passages. Patients can take them by using a nebulizer, which turns the medication into a mist they can breathe in (inhale). If patients wheeze a lot, they can use a metered-dose inhaler (a small canister that sprays a set amount of medication). The inhaler may come with a spacer, a chamber that connects to the inhaler. This will hold the mist for a moment so the child can breathe it all in. These drugs help some patients. Others get no or little relief from them. But because the drugs are safe, they’re worth trying.
  • Racemic epinephrine. Patients can take this medication with a nebulizer to lower swelling in the airways for a while.
  • Systemic corticosteroids. Medications such as prednisone and dexamethasone may decrease the inflammation, but they won’t change the course of the infection.
  • Antibiotics. These medications won’t affect the RSV infection, but they may be needed when there is also a bacterial infection. These secondary infections include ear infections (or otitis media), pneumonia, and urinary tract infections.
  • Ribavirin. This is the only antiviral medication approved to treat RSV. Patients use a nebulizer several times a day to inhale the drug. It can be awkward to keep taking the drug, and it has only a small effect on RSV. For these reasons, it’s used only for a small number of high-risk patients.

Managing RSV

If patients were healthy before getting RSV, they typically get completely better. However, RSV can be severe, life threatening, or even fatal among high-risk groups.

People who are exposed to RSV usually show their first symptoms in 2 to 8 days (usually 4 to 6) after being exposed to the virus. They will feel sick for about 3 to 7 days. How long it takes them to recover depends on how serious their illness was and their overall health.

Patients will be able to pass RSV on to other people (be contagious) for about 8 days. However, some patients (such as those with weakened immune systems) may be contagious for several weeks.

Long-term effects

Some infants who catch RSV during their first 6 months (and especially their first 3 months) of life develop wheezing and asthma later in life. How this happens isn’t exactly known. It is thought that children born with certain genetic patterns may be more at risk.

Preventing RSV

RSV is highly contagious. Thus, it is extremely important to take all the necessary precautions to keep other children and adults from catching it.

The most effective means of protection are also simple:

  • Avoid crowded places.
  • Avoid close contact with infected people (such as kissing).
  • Avoid sharing cups, bottles, or toys that may have come in contact with the virus. (The virus can live on surfaces for several hours.)
  • Wash hands well with soap and water for at least 20 seconds after coming into contact with an infected person.

High-risk patients can receive monthly shots of the drug palivizumab. This will keep them from getting severe RSV disease. If the disease has already started, the shots will have no effect.


The American Lung Association recommends that patients and caregivers join its Living with Lung Disease support community to connect with others facing this disease. To talk to a trained lung professional, call the American Lung Association’s Lung Helpline at 1-800-LUNGUSA. They can help answer your questions and connect you with additional support.

Announcing the RSV toolkit for clinicians and caregivers!

The CHEST Foundation collaborated with the Preemie Parent Alliance and the National Coalition for Infant Health to create an RSV toolkit. The toolkit is filled with information to help both health care providers and caregivers advocate for infants at risk of contracting RSV. Providers should share these materials with their infant patients’ caregivers and consult them when advocating for your infant patients.

Questions to ask your health care provider

Making notes before your visit and taking along a trusted family member or friend can help you through the first appointment with your provider. Here are some sample questions that may apply to your situation:

  • Is my baby at risk for severe RSV infection?
  • Is my baby a candidate for palivizumab?
  • What is the duration of the RSV season in our city/state?
  • Does my baby need any medications (such as a bronchodilator) if they have a cold?
  • Are babies allowed to drink while they’re sick?
  • Can my other children get sick, too?
  • Should I let my parents kiss the baby?
  • My baby was diagnosed with RSV. Can we still go to his cousin’s birthday party?
  • My baby has RSV, but he is not very sick. Is it OK to take him to see my mother? She’s being treated with chemotherapy for breast cancer.
  • My baby had RSV bronchiolitis when she was 6 months old. Is she going to have asthma as she grows older?