Respiratory syncytial virus (RSV) is an infection in your respiratory system (your airways). It’s usually not serious, but symptoms can be much more severe in young children, older adults, and those with weakened immune systems.

RSV is a major cause of human respiratory infections, particularly among younger children. The infection is most severe and occurs most frequently in young children. In babies, RSV can cause bronchiolitis (inflammation of the small airways in their lungs), pneumonia (inflammation and fluid in one or more than one part of their lungs), or croup (swelling in the throat that leads to breathing difficulties and a cough). In older children, teens, and adults, RSV infection is usually less severe.

RSV infection is seasonal. It usually occurs in late fall to spring (peaking in the cold winter months). RSV commonly occurs as an epidemic. This means that it affects many individuals within a community at the same time. The Centers for Disease Control and Prevention (CDC) report that nearly all children will be infected with RSV by the time they turn 2 years old, but only a small portion of them will have severe symptoms.

RSV is diagnosed using a nasal swab that can be tested for indications of the virus in saliva or other secretions.

Read on to learn more about why the RSV test may be used, what tests are available, and what you’ll need to do based on your test results.

Symptoms of an RSV infection are like those of other types of respiratory infections. Symptoms include:

  • cough
  • sneezing
  • runny nose
  • sore throat
  • wheezing
  • fever
  • decreased appetite

The test is most often performed on premature babies or children under the age of 2 with congenital heart disease, chronic lung disease, or a weakened immune system. According to the CDC, babies and children with these conditions are at highest risk of severe infections, including pneumonia and bronchiolitis.

No special preparation is required for this test. It’s just a quick swab, suction, or wash of your nasal passages to gather enough secretions, or fluids in your nose and throat, to test for the virus.

Be sure to tell your doctor about any medications, prescription or otherwise, you currently take. They may affect the results of this test.

An RSV test may be done in several different ways. All of them are quick, painless, and considered highly effective in diagnosing the presence of the virus:

  • Nasal aspirate. Your doctor uses a suction device to take out a sample of your nasal secretions to test for the presence of the virus.
  • Nasal wash. Your doctor fills a sterile, squeezable bulb-shaped tool with a saline solution, inserts the tip of the bulb into your nostril, slowly squeezes the solution into your nose, then stops squeezing to suck a sample of your secretions into the bulb for testing.
  • Nasopharyngeal (NP) swab. Your doctor slowly inserts a small swab into your nostril until it reaches the back of your nose. They’ll move it around gently to gather a sample of your nasal secretions, then slowly remove it from your nostril.

There are almost no risks associated with this test. You might feel a little uncomfortable or nauseous when a nasal swab is inserted deep into your nose. Your nose might bleed or the tissues may become irritated.

A normal, or negative, result from a nasal test means that there’s most likely no RSV infection.

In most cases, a positive result means that you have an RSV infection. Your doctor will let you know what your next steps should be.

A blood test called the RSV antibody test is also available, but it’s rarely used to diagnose an RSV infection. It’s not good for diagnosing the presence of the virus because the results are often inaccurate when it’s used with young children. The results take a long time to become available and aren’t always accurate because of its limited sensitivity to RSV antibodies. A nasal swab is also more comfortable than a blood test, especially for infants and young children, and it has far fewer risks.

If your doctor does recommend the RSV antibody test, it’s usually performed by a nurse at your doctor’s office or in the hospital. Blood is drawn from a vein, usually at the inside of your elbow. A blood draw typically involves the following steps:

  1. The puncture site is cleaned with an antiseptic.
  2. Your doctor or a nurse wraps an elastic band around your upper arm to make your vein swell with blood.
  3. A needle is gently inserted into your vein to collect blood in an attached vial or tube.
  4. The elastic band is removed from your arm.
  5. The blood sample is sent to a laboratory for analysis.

If you take the RSV antibody test, there’s a slight risk of bleeding, bruising, or infection at the puncture site, as with any blood test. You may feel moderate pain or a sharp prick when the needle is inserted. You may also feel dizzy or lightheaded after the blood draw.

A normal, or negative, blood test result may mean that there are no antibodies for RSV in your blood. This can mean that you’ve never been infected with RSV. These results are not often accurate, especially in babies, even with severe infections. This is because the baby’s antibodies may not be detected because they’re overshadowed by the mother’s antibodies (also called maternally derived antibodies) remaining in their blood after birth.

A positive test result from a baby’s blood test may either indicate that the baby has had an RSV infection (recently or in the past), or their mother has passed RSV antibodies to them in utero (before birth). Again, RSV blood test results may not be accurate. In adults, a positive result can mean they’ve had an RSV infection recently or in the past, but even these results may not accurately reflect the actual presence of antibodies from RSV infection.

In babies with symptoms of an RSV infection and positive test results, hospitalization is often not required because symptoms usually resolve at home in one to two weeks. However, RSV testing is most often done on sicker or higher-risk infants who are most likely to need hospitalization for supportive care until their infections improve. Your doctor may recommend giving your child acetaminophen (Tylenol) to keep any existing fever down or nasal drops to clear out a stuffy nose.

There’s no specific treatment available for RSV infection and, at present, no RSV vaccine has been developed. If you have a severe RSV infection, you may need to stay in the hospital until the infection is fully treated. If you have asthma, an inhaler to widen the air sacs in your lungs (known as a bronchodilator) can help you breathe more easily. Your doctor may recommend using ribavirin (Virazole), an antiviral medication that you can breathe in, if your immune system is weak. A medication called palivizimab (Synagis) is given to some high-risk children under 2 years old to help prevent serious RSV infections.

RSV infection is rarely serious and can be treated successfully in various ways.