Respiratory Syncytial Virus - What you need to know

RSV infection is particularly common in infants and young children and typically causes annual winter epidemics. It has been estimated that virtually all children will have been infected with RSV by the age of 2, and it is the most common cause of bronchiolitis and pneumonia in infants worldwide.

The prevalence of RSV varies by region and is influenced by things such as climate and population density. In the northern hemisphere, epidemics generally begin each November, with a peak in January or February. Cases then decline over the next two months with sporadic cases occurring throughout the remainder of the year. In the southern hemisphere, seasonal outbreaks occur from May to September. 

 While RSV is commonly associated with respiratory infections in children, it can also affect adults, especially older adults and individuals with weakened immune systems or underlying health conditions. In adults, RSV infections are often milder than in infants and young children.

• RSV can be more severe in:
• Premature babies
• Babies under 2 months
• Vulnerable infants with underlying conditions (e.g. born prematurely or with a heart or lung condition or respiratory illness) that increase their risk of acute lower respiratory tract infection

The virus is highly contagious, spreads through respiratory droplets produced by coughing or sneezing and can remain ‘live’ on hard surfaces for up to six hours. Its incubation period (the time from contact with it to symptoms developing) is typically four to six days. 

RSV infections can lead to a spectrum of illness, ranging from mild upper respiratory symptoms similar to the common cold to severe lower respiratory tract infections, such as bronchiolitis and pneumonia. Severe cases, especially in infants, may require treatment in hospital.

Symptoms can vary depending on the age of the individual but in infants and young children, RSV infections commonly present with symptoms similar to those of other respiratory viruses. For most people, an RSV infection usually causes a mild, cold-like illness that goes away in one to two weeks. The common symptoms associated with RSV are:

Coughing

Persistent coughing is a common symptom of RSV infections. The cough may be dry or produce mucus.

Sneezing

People infected with RSV may experience frequent sneezing.

A runny or stuffy nose

Nasal congestion and a runny or stuffy nose are typical symptoms, similar to those seen in the common cold.

Fever

RSV infections often lead to a raised temperature - a common symptom, ranging from mild to moderate.

Wheezing

In some cases, RSV can cause wheezing, especially in infants. Wheezing is a high-pitched sound and may indicate difficulty in breathing.

Rapid breathing

Young babies and infants with RSV infections may have very fast breathing, particularly if the infection progresses to the lower parts of the lungs.

Irritability

Infants and young children with RSV infections may become irritable and have difficulty feeding or sleeping.

For some children, further symptoms can develop over a few days if RSV causes a lower respiratory tract infection - this is called bronchiolitis. These may include:

• A raised temperature
• Rapid or noisy breathing (wheezing and whistling)
• A wet chesty sounding cough
• Difficulty feeding.

Bronchiolitis generally gets worse for 3 days, stays the same for 3 days and then gradually improves although it is common for a cough or wheeze to continue for several weeks after a baby or infant has had bronchiolitis, even if they seem to have otherwise recovered. In some cases, hospital treatment may be required to treat bronchiolitis or pneumonia.

You should contact your GP if you are worried about your child, they have taken less than half their usual amount in their last 2 or 3 feeds, or they have had a dry nappy for 12 hours or more. You should also arrange to see a doctor if your child has a persistent high temperature of 38°C or above, or they appear very tired or irritable.

A bluish colour of the lips or nails - known as cyanosis - may indicate a lack of oxygen in the bloodstream and is a medical emergency. If an individual, particularly an infant, experiences severe symptoms such as difficulty breathing, a persistent high fever, or cyanosis, seek immediate medical attention as prompt medical care is essential in managing severe RSV infections and preventing any complications occurring.

How is RSV diagnosed?

Diagnosing RSV involves a combination of taking a medical history, a clinical examination and laboratory tests. When taking a medical history, a doctor will ask about the patient's symptoms, how long they have been unwell, and any potential exposure to individuals with respiratory infections.

This is followed by a thorough physical examination that helps to assess the severity of any respiratory symptoms, and identify any signs of possible complications (such as pneumonia).

With laboratory testing, the most common method for diagnosing RSV is collecting a respiratory specimen, often through a nasopharyngeal swab. The swab is inserted into the back of the nasal passage to collect a sample that may contain the virus and this is then tested for RSV, usually with a polymerase chain reaction (PCR) test. PCR is a diagnostic method that amplifies and detects the genetic material of the virus. This technique is highly sensitive and specific for identifying RSV..

(Some healthcare settings use rapid antigen tests that provide quicker results than PCR. However, these tests may have a lower sensitivity compared to PCR and so are more commonly used in certain situations, such as in emergency departments for rapid decision-making.)

In severe cases or cases that are causing concern, imaging studies such as chest X-rays may be performed to rule out pneumonia or other respiratory conditions. A simple, rapid and accurate method for assessing hypoxaemia (low blood oxygen levels) in someone with RSV is called pulse oximetry. This is usually done in any infant with moderate to severe symptoms of RSV.

RSV shares similar symptoms with other respiratory viruses, such as:

• Human metapneumovirus. This can cause a clinical picture that is almost identical to RSV.

• Influenza. This accounts for up to a quarter of cases of bronchiolitis and closely mimics RSV. It tends to cause more cases of pneumonia than RSV.

• Parainfluenza. This virus can mimic RSV and causes 10 to 30% of cases of bronchiolitis.

• Bacterial pneumonia. This often causes a fever above 40 degrees C and does not normally cause a wheeze.

• Infant (neonatal) sepsis. This is a medical emergency that often presents with a history of poor feeding and difficulty in breathing (similar to RSV infection in infants), decreased level of consciousness, decreased urine output, temperature instability, and shock.

How is RSV treated?

Treatment depends on how severe the infection is. In mild cases, all that may be required is to stay hydrated, get plenty of rest, and use over-the-counter medication such as paracetamol to ease symptoms. No available treatment shortens the course of bronchiolitis, or causes symptoms to improve faster.

Most children do not require treatment with antibiotics. Antibiotics rarely speed up recovery from uncomplicated RSV and often cause side effects such as rash and diarrhoea. This can also promote the development of antibiotic resistant bacteria.

For severe cases, especially in infants or those with a compromised respiratory function, hospitalisation may be necessary. In hospitalised patients, supportive measures such as oxygen therapy and mechanical ventilation may be used.

For high-risk infants - particularly those born prematurely - a monoclonal antibody called palivizumab is now approved in Europe and the US as a preventive measure during the RSV season.

Preventive measures are crucial in managing RSV infections. Key strategies include:

• Washing your hands often - Wash your hands often with soap and water for 20 seconds. If soap and water are not available, use an alcohol-based hand sanitizer. Washing your hands will help protect you from germs.**

• Keep your hands off your face - Avoid touching your eyes, nose, and mouth with unwashed hands. Germs spread this way.

• Cover your coughs and sneezes - Cover your mouth and nose with a tissue when coughing or sneezing. Throw the tissue away in a bin afterwards.

• Clean and disinfect surfaces - Clean and disinfect surfaces that people frequently touch, such as doorknobs.

• Stay home when you are ill - If possible, stay home from work, school, and public areas if you are sick. This will help protect others from catching your illness.