How RSV Is Diagnosed
Testing can rule out similar infections
Alistair Berg / Getty Images
Medically reviewed by Reza Samad, MD
Respiratory syncytial virus (RSV) is a common viral respiratory infection. It causes an illness akin to a common cold but can cause severe, and even deadly, lung and airway infections in the very young and in people 60 and older.
Many people won’t be able to tell RSV from a common cold or flu bug. Visiting a healthcare provider for testing to confirm an RSV diagnosis isn’t required. But depending on your medical history, your provider may want to run a lab test to confirm an RSV diagnosis for you or your child.
RSV is highly contagious and tends to have a seasonal pattern. In the United States, it peaks in the winter months as kids are back in school and colder weather hits.
This article explores ways to tell if you have RSV and whether you need to get tested for a diagnosis. It will explain how to know if you have RSV or the common cold, how long RSV lasts, and when RSV is no longer contagious.
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RSV Self-Diagnosis
If you or your child has the sniffles, it’s likely a cold, the flu, or another virus like RSV. These are all called respiratory infections. Self-diagnosis of RSV or another specific respiratory virus can be difficult. as they typically have similar symptoms in people who are generally healthy.
If you’re looking to tell which one you have, it comes down to parsing out the symptoms. RSV is more likely to cause a fever and fatigue if it causes serious issues like wheezing and trouble breathing.
RSV vs. Cold Symptoms
The symptoms of RSV in otherwise healthy people are similar to symptoms of a common cold. Sometimes, you only suspect RSV if you know you were in contact with someone who has the virus and has been tested to confirm it.
RSV symptoms tend to come on slowly, in stages. Symptoms of RSV infection usually include:
Runny, stuffy nose
Sneezing
Sore throat
Coughing
Headache
Low fever
Fatigue
Loss of appetite
The symptoms of the common cold are very similar to those of RSV. They usually include:
Runny, stuffy nose
Sneezing
Sore throat
Coughing
Headache
When RSV symptoms get more severe and spread deeper into the lungs (the lower respiratory tract), they can include:
High fever
Wheezing
Serious, significant coughing
Breathing faster than normal
Trouble breathing
Chest tightness
Heart racing
Blue lips, fingers, or skin color
The common cold is much less likely to infect the lungs. It will likely not spread into the lower respiratory system and cause these symptoms.
Is Testing Required to Diagnose RSV?
Testing is not required for RSV diagnosis. For a healthy older child, teen, or adult, a healthcare provider will likely suggest home treatment and rest to wait out RSV or other respiratory infections.
A physical exam and RSV diagnosis test may only be needed if symptoms become severe or a person is at high risk due to age, health conditions, or other factors, like a weakened immune system.
Physical Exam and Lab Tests for RSV
When you see a healthcare provider about an upper respiratory infection looking for an RSV diagnosis, they'll review your symptoms and do a physical exam.
They'll ask about fever, how worn down you feel, and signs of dehydration. They'll also ask about other health issues or medications you're on that may weaken the immune system.
If a very young child has the infection, they'll ask about their health history, including issues related to the heart or lungs or if they were born before 37 weeks gestation.
If you or your child is at risk of RSV complications, the healthcare provider may consider additional testing to confirm an RSV diagnosis and take precautionary steps to monitor you.
There are several lab tests for RSV. They may use samples from your upper airways (like inside the nose) or lower airways (your throat). The sample may be collected with a swab or with a saline wash.
Tests used to detect RSV infection include:
RSV culture test shows the presence of live viruses in a sample. It's less common.
rRT-PCR RSV test is highly sensitive because it looks for viral genes. It's commonly used in older children, teens, and adults. It typically needs to be sent out to a lab.
Rapid antigen RSV test is sensitive in children (detects the infection 80% to 90% of the time) and is one of the more common testing options for young ones. It detects proteins in the virus. It is less sensitive than PCR-based tests, which is a problem in older children and adults with lower viral loads (amount of virus in the body). It's less commonly used for older children and adults for this reason.
Sera RSV test is used for research and surveillance of RSV levels in a community. This test uses your blood to see if you've recently had an RSV infection.
Some combined tests for RSV and other viruses can help you or the healthcare professional differentiate between an RSV diagnosis and another respiratory virus.
A healthcare provider can order a respiratory pathogens panel that simultaneously checks for RSV and other respiratory viruses and bacteria. This is useful if your symptoms don't give a precise RSV diagnosis.
You can also buy an at-home test kit to check for RSV, flu, and COVID-19 with one sample without a prescription or a healthcare provider's lab order. This requires you to swab your nose and send the sample to a lab for testing. You get results one or two days after the lab receives the sample.
How Long Is RSV Contagious?
RSV is a very contagious virus. It spreads quickly from person to person through touch or the air. It also spreads from surfaces like a tabletop or doorknob to a person when they touch their face. The germ can live on surfaces for many hours. That’s why this virus spreads easily in educational settings.
After you’ve acquired RSV, you usually don’t start having symptoms until three to five days later. Most healthy adults and children with RSV will improve in a week or two after symptoms begin.
When infected with RSV, you usually become contagious one or two days before symptoms appear. You can transmit it for three to eight days.
A person with a weakened immune system may have more trouble clearing the virus from their system. They may stay contagious for up to four weeks, even after they seem to have recovered and have stopped having symptoms.
When to See a Healthcare Provider
If you think you have RSV, you may be tempted to talk to a healthcare provider about it. Most cases of RSV in healthy adults clear up on their own. Because there's not much treatment can do, most of the time, healing at home is the best treatment option.
Talk to your healthcare provider if your (or your child's) symptoms are severe and you are worried or at high risk due to other factors.
If your infant has a respiratory infection, seek urgent care if they:
Are having trouble breathing, breathing fast, wheezing, or if their nostrils are flaring out with each breath
Are sucking in the skin around the ribcage with each breath, a "caving in" of the chest between the ribs and under the ribs, called retractions
Are not eating
Have a fast pulse or a rapid heartbeat
Are extremely drowsy and not responding to stimuli
Have back pain, neck pain, or neck stiffness
Have a shallow cough day and night, severe coughing spells, or coughing up blood
May be dehydrated; for example, they are not drinking enough, not urinating (peeing) enough, or have dark-colored urine (pee)
Are dizzy, light-headed, or passing out
Have a seizure
Are grunting a lot
Have blue lips, fingers, or skin, a symptom called cyanosis
If you are over 60 or at high risk of severe complications from RSV, talk to a healthcare provider about getting an RSV vaccine. If you have an infant at high risk, talk to their pediatrician about preventive treatment with monoclonal antibodies.
Summary
Respiratory syncytial virus (RSV) is a viral infection. Its symptoms resemble the common cold. But it can lead to severe lung and airway infections in infants and older adults. RSV is highly contagious and seasonal, peaking in winter.
Differentiating RSV from a cold or flu can be challenging since symptoms overlap. Common symptoms of RSV and a cold include runny nose, sneezing, sore throat, coughing, and headache. Symptoms of RSV that are less common in colds include fever, fatigue, wheezing, and breathing issues.
RSV diagnosis usually doesn't require testing, especially for healthy people. Treatment includes resting at home and staying hydrated. A healthcare provider may want to diagnose RSV with a lab test if symptoms are severe or you are at high risk of complications.
Lab tests include RSV culture, rRT-PCR, and rapid antigen tests. Combined tests can help distinguish RSV from other respiratory infections.
RSV spreads easily through touch, air, and surfaces. The contagious period begins one to two days before symptoms emerge, lasting up to eight days. People with a weakened immune system may be contagious for up to four weeks.
Most RSV cases in healthy adults resolve independently with at-home care. Severe symptoms, especially in infants and high-risk individuals, warrant medical attention. Notable signs include breathing difficulties, decreased activity, and bluish skin. An RSV vaccine and monoclonal antibodies offer preventive measures for high-risk groups.
