Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is a common virus that nearly all children catch before they turn two years old, yet it remains one of the most serious respiratory infections for babies, older adults, and people with certain health conditions.

Table of contents

• What is Respiratory Syncytial Virus
• How RSV Spreads
• Signs and Symptoms
• Who is at Higher Risk
• Possible Complications
• How RSV is Diagnosed
• Treatment and Care
• Prevention and Vaccines
• When RSV Season Occurs

What is Respiratory Syncytial Virus

Respiratory syncytial virus, commonly called RSV, is a virus that infects the nose, throat, and lungs, causing infections of the respiratory tract^[1]. The virus is so common that almost all children get infected with it at least once before they reach two years of age^[2]. While RSV usually causes mild, cold-like symptoms similar to the common cold in most people, it can lead to serious illness in certain groups^[2].

In the United States, RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lungs) and pneumonia (infection of the lungs) in children younger than one year of age^[2]. Each year, RSV causes approximately 2.1 million visits to doctors’ offices and 58,000 to 80,000 hospital stays among children younger than five years^[3].

Adults can also get RSV, and you can be infected with the virus multiple times throughout your life. The protection your body builds after being infected doesn’t last forever, so you can catch RSV more than once, sometimes even twice in the same year^[5].

How RSV Spreads

RSV spreads easily from person to person in several ways^[4]. The virus can travel through the air when an infected person coughs or sneezes, sending tiny droplets into the surrounding space^[3]. You can also catch RSV through direct contact, such as kissing the face of a child who has the infection^[4].

Another common way RSV spreads is by touching objects or surfaces that have the virus on them, then touching your mouth, nose, or eyes before washing your hands^[4]. The virus can survive for many hours on hard surfaces like tables, countertops, cribs, and phones^[3][5]. On soft surfaces like tissues or hands, RSV typically lives for shorter amounts of time^[3].

Children often get exposed to RSV outside the home at places like school or daycare, and they can then bring it home to other family members^[3]. People with RSV are usually contagious (able to spread the virus to others) for three to eight days^[4][5]. However, you may be able to spread the virus a day or two before you even develop symptoms^[5]. Babies and people with weakened immune systems can continue spreading the virus for as long as four weeks, even after their symptoms improve^[4][5].

Signs and Symptoms

Symptoms of RSV infection usually begin about four to six days after you are exposed to the virus^[1][4]. In adults and older children, RSV typically causes mild cold-like symptoms^[1]. These symptoms usually appear in stages rather than all at once^[4].

Common symptoms include^[1][4]:

• Runny or congested nose
• Cough
• Sneezing
• Fever
• Sore throat
• Headache
• Decreased appetite
• Wheezing (a high-pitched sound when breathing)

In very young infants, the symptoms may look different. The only signs might be irritability, decreased activity, fussiness, less feeding, and trouble breathing^[1][4]. Babies might also seem unusually tired or not want to play as they normally would^[5].

In severe cases, RSV infection can spread to the lower respiratory tract. Signs of more serious illness include^[1]:

• Severe cough
• Rapid breathing or difficulty breathing
• Short, shallow breathing with long pauses
• Struggling to breathe, with chest muscles and skin pulling inward with each breath
• Nostrils spreading out when breathing
• Wheezing
• Bluish or grayish color of the skin, lips, or nails due to lack of oxygen
• Poor feeding or trouble drinking fluids

Most people with RSV get better on their own in one to two weeks^[3]. However, symptoms like coughing may last for several days to several weeks^[6].

Who is at Higher Risk

RSV can affect people of all ages, but certain groups are at higher risk of developing severe illness that may require hospitalization^[4].

People at highest risk include^[2][3][4]:

• Infants, especially those younger than six months old
• Premature infants (babies born early)
• Children under two years of age, particularly those with small airways
• Older adults, especially those age 65 and older or age 75 and older
• Adults with chronic heart disease or lung disease
• People with weakened immune systems
• Adults with certain medical conditions including diabetes or obesity
• Adults who are frail or live in nursing homes

Infants are most severely affected by RSV because their immune systems are still developing and their smaller airways are more likely to become inflamed^[5]. It is important to note that roughly 80% of children younger than two years who are hospitalized with RSV do not have known risk factors^[3].

In the United States, RSV leads to approximately 100,000 to 160,000 hospitalizations in adults age 60 years and older each year^[3].

Possible Complications

RSV can cause complications that make it harder to breathe^[5]. The infection can spread to the lower respiratory tract, causing more serious conditions such as^[1][2]:

• Pneumonia – an infection of the lungs
• Bronchiolitis – inflammation of the small airway passages in the lungs
• Bronchitis – inflammation of the larger airways

Other possible complications include^[5]:

• Worsening of existing conditions like asthma, congestive heart failure, or chronic obstructive pulmonary disease (COPD)
• Respiratory failure
• Low oxygen levels in the blood
• Dehydration (loss of body fluids)
• Ear infections

In most severe cases, a person may need additional oxygen, fluids given through a vein, or even a breathing tube inserted through the mouth with a machine to help them breathe^[2]. Most hospital stays for RSV last only a few days^[2].

How RSV is Diagnosed

Your healthcare provider can often diagnose RSV based on a physical examination and the time of year when symptoms appear^[9]. During the exam, the doctor will listen to your lungs with a stethoscope to check for wheezing or other abnormal sounds^[9].

Laboratory tests are not always needed but may be used in certain situations^[4][9]. To diagnose RSV, a healthcare provider may use:

• A medical history, including questions about your symptoms
• A physical examination
• A lab test using a swab from inside the nose or mouth to check for the virus. This is usually done for people with severe infection^[4][5]
• Tests to check for complications in people with severe infection, which may include a chest X-ray, blood tests, or urine tests^[4]
• A test to measure oxygen levels in the blood using a painless skin monitor^[9]

Because RSV symptoms are similar to those of other respiratory viruses like flu and COVID-19, it can be difficult to know if someone has RSV without a confirmed lab test^[3].

Treatment and Care

There is no specific medicine or treatment that cures RSV infection^[4][10]. Most RSV infections go away on their own within a week or two^[4][10]. Treatment is mainly focused on supportive care, which means making the person more comfortable and managing their symptoms^[9].

For mild illness that can be managed at home, supportive care includes^[9][10]:

• Using over-the-counter medicines such as acetaminophen to reduce fever and relieve pain. Never give aspirin to children^[9]
• Drinking plenty of fluids to prevent dehydration^[4][10]
• Using nasal saline drops and gentle suctioning to help clear a stuffy nose^[9]
• Watching for signs of dehydration, such as dry mouth, little to no urine output, sunken eyes, and extreme fussiness or sleepiness^[9]
• Avoiding cough medicine for children under four years old^[4]

If RSV causes severe symptoms or complications, a hospital stay may be necessary^[4]. Hospital treatments may include^[9]:

• Fluids given through a vein
• Oxygen given through a mask or nasal tubes
• A breathing machine (mechanical ventilation) in rare cases
• An inhaler (bronchodilator) or steroid medication in some cases

Your doctor may prescribe antibiotics if there is a bacterial complication, such as bacterial pneumonia, but antibiotics do not work against the virus itself^[9].

Prevention and Vaccines

Several immunization options are now available to help protect against severe RSV illness^[2][4].

For pregnant people: A vaccine called RSVpreF (Abrysvo) can be given between 32 and 36 weeks of pregnancy during RSV season (September through January)^[4]. This maternal RSV vaccine helps protect newborn babies from RSV illness for the first six months of life^[4]. The vaccine reduces the risk of RSV hospitalization for babies by 57% in their first six months^[14]. If you received the RSV vaccine during any pregnancy, you should not get another dose if you are pregnant again^[14].

For infants and young children: There are two medicines given by injection (shots) to help prevent severe RSV illness in babies and young children^[4]. One medicine, called Beyfortus (Nirsevimab), is recommended by the Centers for Disease Control and Prevention for babies before or during their first RSV season^[14]. These medicines may help prevent severe RSV illness, but they cannot cure or treat children who already have RSV, and they cannot prevent an RSV infection entirely^[4].

Young children with a very high risk of getting seriously ill from RSV may be given an injection of infection-fighting antibodies each winter to help reduce the risk of severe bronchiolitis^[8].

For older adults: Three RSV vaccines are available for adults. A single lifetime dose of RSV vaccine is recommended for all adults age 75 years and older, and for adults age 50 to 74 years who have certain chronic health conditions such as lung disease, heart disease, weakened immune systems, or who live in nursing homes^[3][4]. If you are in this age group, talk to your healthcare provider about whether an RSV vaccine is right for you^[4].

Everyone can take steps to help prevent the spread of RSV^[2][3]:

• Cover your coughs and sneezes with a tissue and throw it away immediately
• Wash your hands often with soap and water for at least 20 seconds
• Avoid close contact with others when you are sick
• Avoid touching your eyes, nose, or mouth with unwashed hands
• Clean frequently touched surfaces such as toys, countertops, and doorknobs regularly
• Try to keep newborn babies away from anyone with a cold or flu, especially if the baby was born prematurely or has serious health conditions
• Stay home and away from others when you are sick

When RSV Season Occurs

In most regions of the United States and other areas with similar climates, RSV season generally starts during the fall and peaks in the winter^[4][21]. It usually peaks in December and January^[2]. The timing and severity of RSV season can vary from year to year and by location^[21].

RSV spreads in the fall and winter months along with other respiratory viruses like influenza and COVID-19^[2]. Over the course of each fall and winter respiratory virus season, RSV reaches all parts of the continental United States^[21].