RSV (Respiratory Syncytial Virus)

No preparation is needed. The sample is usually taken from the nose. The most common method is a nasal aspirate — a gentle suction of mucus from the nostril. A nasopharyngeal swab (a swab taken from the back of the nose and throat) or a throat swab may be used instead. The procedure is quick, though a nasopharyngeal swab can feel briefly uncomfortable. 

Because RSV is only detectable in nasal secretions during the first few days of infection, it is best to be tested as early in the illness as possible. The amount of virus shed decreases as the illness progresses, which means testing after several days of symptoms may be less likely to detect the virus even if RSV is the cause.

What the test measures 

RSV testing looks for signs of the virus in your nasal secretions. There are two main types of test: 

• Rapid lateral flow test — this can be carried out at the bedside or on the ward. It looks for viral proteins (pieces of the virus itself) in the sample. Results are usually available within 30 to 60 minutes. It is quick and convenient, but it is slightly less sensitive than laboratory testing, meaning it can sometimes miss the virus if it is only present in small amounts 
• PCR (polymerase chain reaction) test — this is a more sensitive laboratory test that looks for the genetic material (RNA) of the virus. It can detect RSV even when only very small amounts are present. This test is often set up to check for several other respiratory viruses at the same time — including influenza, parainfluenza, and rhinovirus — which gives your doctor much more information about what is causing your symptoms. Results are usually available on the same day the sample is collected, though samples sent to a different laboratory site may take longer 

Some hospitals now use compact ​‘near-patient’ PCR machines that can perform molecular testing on the ward, combining the speed of rapid testing with the sensitivity of laboratory PCR. 

What your results mean 

If your RSV test is positive 

A positive RSV test means the virus was detected in your sample. This confirms that RSV is the likely cause of your current symptoms. RSV usually causes cold-like symptoms including: 

• runny or blocked nose 
• sneezing and coughing 
• mild fever 
• sore throat 

In young babies, additional symptoms can include rapid breathing, a high-pitched wheezing sound when breathing, poor feeding, and unusual tiredness or irritability. These symptoms may indicate bronchiolitis, which can sometimes need hospital admission for monitoring and supportive care. 

A positive result cannot tell your doctor how severe your symptoms are likely to be, or at exactly what point during your illness you are. Most people with RSV recover fully within one to two weeks. There is no antibiotic treatment for RSV as it is caused by a virus, not a bacterium — antibiotics will not help. 

For most people, treatment focuses on managing symptoms: staying hydrated, resting, and using paracetamol or ibuprofen if needed to reduce fever. If you or your child are struggling to breathe, not feeding, or becoming very unwell, seek medical advice promptly. 

RSV vaccine is available for some age groups (see link below). 

If your RSV test is negative 

A negative result means RSV was not detected in your sample. This could mean: 

• you do not have RSV, and your symptoms are caused by a different virus or infection 
• you have RSV but the virus level in your sample was below the detection threshold — this is more likely if you were tested several days into your illness, or if the sample was not collected well 
• adults generally shed lower levels of virus than infants, which can make the virus harder to detect 

If you or your child are still unwell and RSV is strongly suspected despite a negative rapid test, your doctor may send a sample for PCR testing, which is more sensitive. If the PCR result also includes other viruses tested at the same time, your doctor may be able to identify a different cause of the symptoms. 

A negative RSV test does not rule out other respiratory infections. Your doctor may request further tests if they suspect a bacterial infection, influenza, or another cause. 

For most people, RSV is a self-limiting illness — it gets better on its own within one to two weeks without any specific treatment. Antibiotics are not effective against RSV and should not be used unless there is evidence of a secondary bacterial infection. 

If your test is positive and you or your child are managing symptoms at home, focus on rest, fluids, and fever management. Contact your GP or seek urgent medical attention if breathing becomes laboured, if a baby is not feeding, if a fever is very high or not settling, or if symptoms are getting rapidly worse. 

For hospitalised patients and those in high-risk groups, antiviral treatments are available in some circumstances. These are not suitable for most people with mild RSV illness but may be considered for severely immunocompromised patients. Your specialist team will advise if antiviral treatment is appropriate. 

For premature babies and infants with certain heart or lung conditions, a preventive treatment called palivizumab (a monthly injection given during RSV season) may have been prescribed before the illness. If your baby is already receiving this, tell the healthcare team. 

People can be re-infected with RSV each year, because the virus has different strains and immunity is not long-lasting. However, repeat infections in otherwise healthy people tend to be milder than the first infection. 

• Timing of the test — RSV is most detectable in the first 2 to 4 days of illness. Testing later in the illness, when virus shedding has dropped, increases the chance of a false negative result 
• Age — adults shed lower levels of virus than infants and young children, which makes detection harder. A negative result in a symptomatic adult does not firmly exclude RSV 
• Sample quality — a poorly collected sample, or one that has not been stored and transported correctly, may give a false negative result 
• Type of test used — rapid lateral flow tests are less sensitive than PCR. A negative lateral flow result in someone with strong clinical suspicion of RSV may be followed up with a more sensitive PCR test 
• Immune status — immunocompromised patients may shed virus for longer than immunocompetent people, which can affect how results are interpreted 

• Influenza tests — RSV and influenza can cause very similar symptoms and circulate at the same time each winter; testing for both together is common. Many respiratory PCR panels test for both viruses simultaneously 
• Pertussis (whooping cough) — may be considered in infants with a persistent or severe cough where pertussis is a possibility alongside RSV 
• Bacterial throat swab or culture — if a bacterial infection such as streptococcal throat infection is also suspected, a swab may be taken for culture 
• Chest X‑ray — may be requested in hospitalised patients to assess the extent of lower respiratory involvement, such as pneumonia or bronchiolitis 
• Blood tests — in unwell or hospitalised patients, a full blood count and C‑reactive protein may be requested to assess the severity of illness and check for secondary bacterial infection