Respiratory Syncytial Virus or RSV is a respiratory virus that infects the lungs and breathing passages. It is widely spread and especially common during the cold autumn, winter and spring months. Everyone is at risk of contracting RSV which affects almost every child and most will have been infected with the virus by the age of two. 

The majority of healthy people will experience flu-like symptoms while people with a weak immune system, for example the elderly and very young children, have a high risk of severe infection from RSV. People ill with chronic lung diseases, preterm infants, children with compromised immune systems, children with heart disease or children with Down Syndrome have also much higher rates of severe RSV infections. The same goes for those with neuromuscular diseases. Chronic disease per se is an important risk factor for RSV hospitalisation and makes a severe infection more likely.

We have summarised the most important information about RSV in a comprehensive factsheet that can be downloaded here.

What makes RSV dangerous?

RSV is the primary cause of bronchiolitis which is an inflammation of the bronchial tubes (small airways in the lungs) and lungs. Bronchiolitis (not to be confused with bronchitis) is the most common infection of the lower airways in infants. The majority of bronchiolitis hospital admissions have been caused by RSV. 

RSV is also a common cause of pneumonia, which is a lower respiratory tract infection. It causes the air sacs of the lungs (the alveoli) and the smaller bronchial tubes to become inflamed and fill with fluid. An affected child might be unable to breath and will not get enough air. 

Unfortunately there is no treatment for an acute RSV infection available that can combat the cause of the disease. Only the symptoms can be treated. 

What factors increase the risk of RSV?

Children are at higher risk if they attend childcare centres or if their older siblings attend school, hence by being more exposed to RSV through contact. A family history of asthma also increases the risk of a more severe infection. The same goes for being exposed to tobacco smoke and other air pollution. Multiple birth siblings are also at higher risk as they are often born preterm and with a low birth weight. Moreover, they tend to (re)infect each other and are therefore more at risk to catch the virus.

Outbreaks of RSV infection occur on a yearly basis, usually during the colder months of a year. Epidemics of RSV typically last approximately five months (from October to April in the northern parts of the globe and from July to September in the southern parts of the globe).

However, in recent years RSV-season has been started in September already in Western and Central Europe. Often, the season finds its peak in January and February, less often in November and December. 

Why are preterm infants more likely to get infected by RSV?

Whilst full-term infants receive antibodies through their mother during the pregnancy, preterm infants did not get enough maternal antibodies over the placenta. Therefore, preterm infants are more likely to contract the RSV in the first few weeks of their life and onwards. Furthermore, preterm infants are often artificially respirated which might damage their lung tissue leading to the chronic lung disease BPD (bronchopulmonary dysplasia). These children are therefore more likely to contracting RSV as well as to go through a more severe acute infection because their bodies already limit their oxygen supply. 

What are the symptoms of RSV?

In the beginning, the initial symptoms of bronchiolitis often resemble the common cold. 

Symptoms can be:

  • a runny or blocked nose
  • an increased body temperature 
  • a decrease in appetite
  • a dry, “croupy” cough (often described as a “seal bark” cough)
  • breathing difficulties 

Further symptoms of RSV might include:

  • persistent coughing and wheezing
  • high fever 
  • sudden gasping for breath 

Pneumonia caused by RSV has flu-like symptoms but can also include:

  • coughing with mucus (possibly green, rusty or blood stained)
  • shortness of breath
  • chest pain


Should a newborn and especially a child at risk or with chronic disease show any of these symptoms, it is important to contact a healthcare professional immediately.

How is RSV transmitted?

The virus is spread by infected people sneezing or coughing whilst releasing droplets containing the virus into the air, which are then breathed in or come in contact with the mouth, nose or eye(s) of someone else. Infection can even occur when one touches their mouth, nose, or eyes after touching a contaminated object or surface.

The RSV virus spreads rapidly and can live for half an hour or more on hands, up to five hours on objects and worktop surfaces and for several hours on used tissues.. 

The incubation period of RSV is between 2 – 8 days, on average it is 5 days. Some people infected with RSV show the first symptoms one day after having contracted the virus. Generally most people with a strong immune system are contagiousness for 3 – 8 days. However, preterm infants, infants and patients with immune deficiencies can be infectious for several weeks, rarely even for months according to the Robert Koch Institut. 

How can the RSV risk be lowered?

There is no RSV vaccine but preventive therapy has proved an important strategy to manage the virus. Parents of preterm infants and children at risk should consult with a health professional for more information. For example, children at particular risk can be supported in their defense against RSV using a special protective approach known as passive immunisation.

To reduce the risk of infection with RSV, the following preventive steps should also be adapted:

  • Covering of the nose and mouth with a tissue when coughing or sneezing
  • Disposal of used tissues in the bin after use
  • Washing of hands often and use soap and warm water (or an alcohol-based cleaner if soap and water is not available; anti-bacterial cleaners do not kill viruses)
  • Touching of preterm infants and newborns only after hands have been washed
  • Avoiding of touching of eyes, nose and mouth as germs can spread in this way
  • Limiting physical contact with anyone who has a cold, fever or runny nose
  • Disinfecting toys, play areas and surfaces (such as table tops) as germs can live for over 24 hours on household items
  • No smoking nearby the baby and changing of clothes which were exposed to smoke (even second-hand smoke) before picking up the child
  • Trying to avoid places where there are lots of people (e.g. public transport, big shopping malls and waiting rooms)


What are the short- and long-term effects of a RSV infection? 

In the short term a RSV infection might lead to either a cold or flu. The more severe cases will result in sometimes life-threatening bronchiolitis, pneumonia, BPD (bronchopulmonary dysplasia) or even death (1 in 100) due to limited lung function. 

Some children who have suffered a severe RSV infection may develop childhood asthma or show symptoms very similar to those of asthma. As a result, they may suffer from the consequences of an RSV infection for an extended period of time.

A child who once contracted RSV does not develop immunity from future RSV infections. It is possible to experience repeated episodes of RSV infection. 

What else can be done to improve  health of children at risk in regards to RSV?

Always monitor your child closely for infections because an early identified infection is easier to manage.

We are thankful to The European Lung Foundation (ELF) who provided us with Factsheets about preterm birth and the lungs which you can download in 9 languages in our position paper and faction section. 

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