The respiratory syncytial virus (RSV) antibody test is a blood test used to diagnose a respiratory syncytial virus (RSV) infection. The test detects the presence of antibodies to the RSV pathogen. Antibodies are proteins that your body’s immune system releases naturally in response to a harmful substance, called an antigen.
Specifically, the RSV test detects the presence of antibodies that your body has produced to fight the RSV virus. The test can be used to diagnose either a recent or a past RSV infection.
RSV is a major cause of human respiratory infections, particularly among the younger populations. The infection is most severe and occurs most frequently in young children. In infants, the virus can cause bronchiolitis (inflammation of the airways in their lungs), pneumonia (inflammation of their lungs) or croup (swelling in their throat that leads to breathing difficulties and a cough). In older children, adolescents, and adults, infection with RSV tends to be less severe.
The infection is seasonal — usually occurring in late fall to spring (peaking in the cold winter months) — and it commonly occurs as an epidemic. This means that it affects a large number of 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 percentage will experience severe symptoms.
Symptoms of an RSV infection are similar to those of other types of respiratory infections. They may include:
- runny nose
- sore throat
- decreased appetite
The test is often performed on premature infants or children under the age of 2 who have congenital heart or chronic lung disease or a weakened immune system. According to the CDC, infants and children with these conditions are at highest risk of severe infections, including pneumonia and bronchiolitis.
No special preparation is required for this test.
Be sure to tell your doctor about any medications — prescription or otherwise — you currently take, because they may affect the results of this test.
The RSV antibody test is a blood test performed by a nurse at your doctor’s office. Blood will be drawn from a vein, usually at the inside of your elbow. A blood draw typically involves the following steps:
- The puncture site is cleaned with an antiseptic.
- A healthcare provider (often your doctor or a nurse) wraps an elastic band around your upper arm in order to make your vein swell with blood.
- A needle is gently inserted into your vein to collect blood in an attached vial or tube.
- The elastic band is removed from your arm.
- The blood sample is sent to a laboratory for analysis.
As with any blood test, there’s a slight risk of bleeding, bruising, or infection at the puncture site. 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, test result indicates that there are no antibodies for RSV in your blood. This means that you’ve never been infected with RSV.
In infants, a positive test result may 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). In adults, a positive result means they have had an RSV infection recently or in the past.
Your doctor can use the results of your test to distinguish between a recent and a past infection. In general, the presence of IgM antibodies indicates recent infection, and the presence of IgG antibodies indicates past infection. Most adults and older children have already had an RSV infection and already have RSV antibodies.
In infants with symptoms of an RSV infection and positive test results, hospitalization is typically not required because symptoms usually resolve at home in one to two weeks. The CDC states that most children who need to be hospitalized for RSV infection are younger than 6 months of age. There’s no specific treatment available for RSV infection and, at present, no RSV vaccine has been developed.