Risks and Severity

RSV, the “respiratory syncytial virus”, is the virus at the origin of a very common respiratory infection in infants; however, it can occur at any age.  

Risk of severe infections

An RSV infection starts in the upper respiratory tract (nose and throat) but it can develop into an infection of the lower respiratory tract, particularly in infants and the elderly, in whom it then causes bronchiolitis (an infection of the smallest airways) or pneumonia.

DID YOU KNOW? As for all viral infections, an RSV infection can cause weakening of the immune system and favour the development of viral or bacterial superinfections, accompanied by high fever.

Bronchiolitis in infants

Bronchiolitis is inflammation of the pulmonary bronchioles, the smallest branches of the airways. 

RSV is the principal cause of bronchiolitis in children: between 25% and 40% of children suffer the symptoms of bronchiolitis during their first RSV infection.

This infection is very common and often benign, but it can be serious in the very young. 

Parents should carefully monitor the respiratory signs which might suggest a worsening of the RSV infection and should be very aware of the risk of dehydration.

Breathing difficulties in infants and premature babies often require hospitalisation in intensive care: 1% to 3% of children with an RSV infection have to be hospitalised because of serious respiratory symptoms. 

Premature babies and children suffering from cardiovascular or lung diseases are more exposed to the risk of severe infections and reinfections.

Complications of an RSV infection in adults

In adults an RSV infection can cause pneumonia, particularly in: 

  • the elderly
  • persons with a weakened immune system (immunocompromised).
  • persons with pulmonary problems 
  • persons with cardiovascular problems.


Sciensano centralises and analyses all data provided by the different partners (network of sentinel laboratories and the National Reference Centre) and in this way is able to follow up the evolution of RSV infections.


There are currently no projects associated to this health topic


There are currently no events associated to this health topic

Other sources of information

There are currently no external links associated to this health topic

In the media

There are currently no media associated to this health topic

QR code

QR code for this page URL